Technical questions often asked by farmers about Nutrition Management.
Information regarding the nutritional responses of grapes to liquid fertilisers is scarce, especially in relation to drip or micro sprinkler irrigation. The widespread adoption of drip irrigation in Australia has highlighted the importance of achieving quality and productivity of crops through controlled nutrition and irrigation.
Before the advent of drip irrigation for grapevines, NPKS fertilisers were spread on the soil between rows followed by shallow incorporation. Response to potassium in K-fixing soils, for example, sometimes took two years before it could be detected or measured. Nowadays, balanced liquid formulations containing NPK, secondary nutrients and trace elements can bring about an almost immediate growth response from the vine when they are applied through the drip line. This is because vine roots become concentrated not far below the drippers, which provide the all-important water and nutrients to the vine.
By using drip or micro sprinkler irrigation, nutrients can be targeted for instant uptake, increasing fertiliser-use efficiency with significant savings in fertiliser, increased quality and productivity. Some growers have now started to improve nutrient uptake through optimising soil pH by applying liquid lime (see Technical Questions) through the drippers. If liquid lime is to be added through drippers, stainless steel filters of a suitable mesh size should be used to prevent blockage of drippers. Increasing the soil pH close to drippers with liquid lime, to pH 6 – 6.5, is particularly useful for reducing aluminium activity and toxicity in acid soils.
An emerging area of interest in grapevine nutrition is the relationship between nutrition and watering regimes to vine growth and grape quality, which is so important for making good-tasting wine. Additional water improves uptake of soluble nitrogen, potassium and phosphorus, but with grapes there is a conflicting need to limit the water supply, using deficit irrigation, to improve quality, The role of organic matter in this regard is very important, and we should see advances in this area. Other interesting areas are the role of calcium, magnesium and sulphur in relation to NPK and trace elements on leaf photosynthesis function, cluster and berry size; and the nutrient uptake differences between varieties.
Now more than ever, the enormous increase in the number of newly established vineyards in Australia will create a demand for quality grapes leading to increasing reliance on improved nutrition. Western Fertiliser Technology Pty Ltd is a supplier of quality liquid fertiliser products ideally suited for application through drip irrigation for your vines. Their exceptional solubility and availability to plants derives from the use of quality ingredients in a natural organic base of fish emulsion, and the inclusion with NPKS of calcium and magnesium-buffered compounds and trace element chelates able to maintain their solubility and availability within a wide pH range.
The links between quality, productivity and nutrition
Frequently, it is seen that many vineyards established on marginal or nutrient-depleted soils suffer a decline in the quality and quantity of grapes, together with an increased incidence of leaf and root disease and insect pests. The cause is often a weak link in nutrition, which can be easily corrected through foliar or drip applications. Often, the problem is due to an acid soil pH and soluble aluminium at pH levels of 5 down to 3.5, which interferes with the biological mineralisation and uptake of nutrients by roots. Soluble aluminium disrupts rapidly growing meristem tissue. Lime is obviously needed, but the type of lime is important if the aluminium and acidic compounds are to be removed without soil disturbance.
The technology and use of liquid lime has been discussed earlier (see Technical Questions), and its timing and amounts to apply is particularly relevant in dripper irrigation. Liquid lime should be judiciously applied to raise the soil pH around the drippers (where the roots are) in a steady sustained way without causing any nutrient imbalances. The availability of the irrigated nutrients and vine health should improve with a steady decrease of soil acids, the reduction of toxic aluminium compounds, and an increase of beneficial microbial activity.
Less damage by disease and pests
A reduction in the incidence of disease and pest problems has been reported with the use of WFT products. The NPK and micronutrients in WFT products improves photosynthesis markedly in foliage, which is able to synthesise a full range of sugars and proteins needed for energy and immunity function to resist disease and pests. Insect pests are less attracted to leaves and fruit containing a high level of soluble sugar and other carbohydrates. The sugars and proteins are mobilised to the roots, which then have the energy to assimilate needed minerals from applied fertiliser and the soil. Potassium, calcium and magnesium are particularly important nutrients in this regard, as they play a role in root cell turgidity which offers protection against fungal attack, and the buffer-control of cell-sap pH for optimum enzymic activity. Calcium containing liquid fertilisers helps to improve water infiltration and to counter a reduction in water infiltration from potassium.
Winegrowers report increased vigour and resistance to frost damage, and fungal diseases such as mildew and bunch rot, together with decreased activity of insect pests. Fungicides will treat disease infection, but they cannot cure disease due to nutrient deficiency. Growers also report crops being able to withstand very hot conditions without visible moisture stress. Use of WFT products have also been attributed to improved colour development, uniform size of berries and sweetness, which can be related to enhanced photosynthesis and general vine health.
Nutritional aspects of management
If you intend to increase the size of your vineyard, determine whether soil amendments are needed, by sending a soil sample for analysis; usually pH, organic carbon, electrical conductivity, exchangeable potassium and sodium, and Calcium, Magnesium, Boron, and Phosphorus levels. Grapes are tolerant to quite a wide range of soil pH and textures. However they perform best where soil pH is between 5.5 and 7.0. If adding lime to depth at planting, dolomitic lime (CaCO3.MgCO3) containing both calcium and magnesium is preferable to calcium-only limestone (CaCO3).
Wine quality is strongly influenced by nutrition, cultivar, fruit quality and freedom from disease; and of course, the ability of the vintner to create an unforgettable wine. When you are selecting cultivars to grow, it is advisable to obtain local recommendations to suit the type of soil. In the famous Margaret River region of Western Australia, European wine grapes such as Cabernet Sauvignon, Shiraz, Merlot, Pinot Noir, Chardonnay, Riesling, etc are popular.
Grapes benefit from shallow cultivation in the early part of the season, taking care not to disturb roots. A legume cover crop between the rows should provide nitrogen and humus and reduce erosion. It is best to delay pruning to increase cold hardiness. Late pruning allows the small stems to translocate most of their nutrient resources back to the main stem, conserving nutrients. Practise balanced pruning as excessive pruning results in excessive vegetative growth and lower quality fruit due to less K, Ca and Mg in the fruit. The optimum number of buds (nodes) to retain will depend on the variety you choose, which will affect quality and productivity due to how well nutrients are shared. The ideal grape canopy has a large number of leaves set for maximum sunlight exposure for photosynthesis, maximising fruit yield and quality. Positioning of shoots for sunlight exposure (on both sides of the canopy) should be done before bloom.
Use nitrogen judiciously, as high nitrates can cause a large number of immature green shoots and delayed ripening. However, if nitrogen is needed to boost growth, liquid fertilisers containing potassium nitrate and calcium nitrate are preferable.
Thinning of flower-clusters before bloom complements pruning to improve quality of grapes and increase cluster size and length by conserving nutrients. However, if balanced and adequate nutrition is practiced, thinning can be avoided (saves labour), whilst increasing yields considerably.
Liquid Fertilisers
An early start to feeding has a pronounced effect on productivity and quality as time is made available for the translocation of less mobile but vital nutrients to growing points. Apply liquid fertiliser on a weekly basis through the drip line. Complete nutrient-balanced formulations such as Super Liquid NPK and Mono Calphos containing nitrogen and micronutrients, applied early, promotes early spring growth and allows reduced levels of nitrates in tissues in late summer, improving quality.
Base fertiliser applications on the amount and quality of vegetative growth and petiole analysis as the season progresses. Petioles should be sampled at veraison, and the most recently matured leaf is usually chosen. Wash petioles in distilled water and dry thoroughly before sending away for analysis.
If growth is excessive, reduce the quantity of the balanced fertiliser. If leaves have poor colour, and pruning weights are low, increase the amount of liquid fertiliser used.
Phosphorus levels in the vines should be maintained at adequate to high levels early in the season for optimum photosynthesis and yield. Low levels of phosphorus are often due to insufficient nitrogen, low organic matter in the soil, high soil aluminium or the use of an inappropriate type of liquid fertiliser. Mono Calphos, Super Liquid NPK and Hortigro are ideal for supplying rapidly available phosphorus together with other nutrients. Calcium and magnesium are useful as balancing nutrients for soils supplying very high potassium. Deficiencies of calcium, magnesium and sulphur, combined with high potassium can affect wine-keeping quality.
Deficiency of potassium in sandy or gravel type soils can be avoided by using high K liquid fertilisers such as NPK Green. Deficiency causes uneven colouring of fruit, with fewer and smaller clusters. Severe deficiency leads to dehydrated berries and low sugar levels at harvest.
Copper and manganese deficiencies are common in WA, and can be quickly corrected with Super Energy. Petiole sampling at flowering, followed by timely analysis allows corrective foliar applications. Analysis kits and directions for leaf sampling are available from local suppliers.
Boron is an element to monitor carefully for grapevines. Deficiency leads to yellowed foliage in early growth, and uneven, sometimes deformed fruit and reduced cluster size. Deficiency is rapidly corrected by applying Soil and Foliar Boron. Interpretation of leaf disorders is best accomplished by sending for analysis samples of poor growth together with good growth from healthy vines for comparison.
Nutrition at harvesting
Grapes should be harvested in the morning after the dew has dried, or post-harvest diseases can be a problem. Keeping the vineyard mowed and free from weeds speeds fruit drying. As the fruit approaches maturity, use a hand refractometer to determine an acceptable sugar level for harvest (approximately 16 to 21 per cent as glucose). Harvest vines more than once to maximise yield and quality. After the ripe clusters are removed, the smaller immature clusters will rapidly ripen and increase in sugar content. Cut defective portions of clusters by clipping off the berry stems.
The alcohol content of the wine depends on the sugar content at harvest. Consistently low sugar levels at harvest indicate that photosynthesis is not proceeding as well as it should during growth. Photosynthesis can be improved with a phosphate and micronutrient fertiliser containing nitrogen, potash, magnesium and sulphur in adequate levels, eg, Super Energy liquid fertiliser.
Some varieties of grapes are susceptible to uneven or delayed ripening. Unbalanced fertilisation with poor vigour, and uncontrolled weeds and grass and heavy shade are some of the problems, including injury from insects or fungus- type diseases. Removing leaves mainly around the clusters, close to harvest, allows better light penetration and helps ripening.
Concepts in Nutrition
Utilisation by plants of the large number of essential nutrients for growth and reproduction is influenced to a great extent by the external environmental factors. These are temperature range, light intensity, air quality, water supply, nutrients supply, together with the presence of beneficial microbes, or the absence/ presence of disease organisms, The understanding of the environmental factors on plant health and productivity has led to a paradigm change to modern dynamic concepts of nutritional management.
The concepts derived from Liebig’s law of the minimum, and Blackman’s law of limiting factors are still very relevant today. However, our understanding of the plant’s relationship with the environmental factors has progressed remarkably; for example microbes living in synergy with plants on the leaf surface (phyllosphere) and the rhizosphere, and the conversion of all simple nutrient forms to more complex but biologically useful organic forms by microbes and plants. Nutritional concepts and management has become much more sophisticated. Another area of improvement in our understanding is that it is futile to consider nutrients in isolation. Plant growth and preparation for reproduction relies on an efficient photosynthesis process linking together complex contributions from all the nutrients.
Multiple deficiencies of nutrients are often responsible for poor performance by plants, and departures of several nutrients simultaneously from optimum levels are serious barriers to obtaining yield maximums (Wallace,A. J. Plant Nutrition., 1986). According to Wallace, nutrient stresses do not act independently, and if four different plant nutrients are present in supply and ratio each at eg. 90% of optimum, and if all the other nutrients are optimum, the additive summation of the nutrient stress is…0.90 X 0.90x 0.90 X0.90 = 0.66 or 66%. Then only 66% of yield maximum is possible, provided that no other major stresses are present. However if one of the four deficient nutrients is only 50% of optimum, nutrient stress is then 0.50 X 0.90 X 0.90 X 0.90 = 0.36 and only 36% of yield maximum is possible.
This explains the devastating effect on yields of multiple nutrient deficiencies. The presence of simultaneously acting multiple deficiencies makes chemical analysis of grape petioles or grain (see Publications: Grain Analysis) of importance in improving yields by correcting deficiencies of major, secondary, trace and ultra-trace elements. Fortunately, the advent of extremely sensitive methods of chemical analysis, notably Inductively Coupled Plasma – Mass Spectrometer is going to substantially increase worldwide the quality and productivity of crops.
Achieving maximum yield for field crops is not an easy task, not only because you have to contend with large areas composed of changing conditions (eg soil types, fertility, drainage etc), but also because you will need to achieve maximum photosynthesis efficiency for your crops.
Photosynthesis efficiency is a highly complex subject, and photosynthesis is, undoubtedly, the most important biological process on earth on which we have to rely on not only for growing crops but also to reduce increasing greenhouse gas and soften the climatic changes associated with it.
Photosynthesis is a seamless energy intensive process, which combines carbon from atmospheric carbon dioxide and water to form carbohydrates and release of oxygen, followed by respiration. Plant respiration is where a part of the carbon fixed as carbohydrate is burned chemically in the tissues for energy generation in the presence of oxygen and release of carbon dioxide. The whole physical and chemical environment around the plant are part of the photosynthesis process, which means each environmental factor will have to be optimum for maximum yield to occur.
Chemically, the process of photosynthesis relies on utilising the absorbed solar radiation to split the chemical bonds of water and combine with carbon dioxide to first form glucose. From glucose is derived proteins (with nitrogen from fertiliser), nucleic acids (nitrogen and phosphate from fertiliser) and other compounds (eg. starch, cellulose, oils and fats).
The whole photosynthesis process relies on the orderly movement of electrons for reduction (gain of electron) and oxidation (loss of electron) for synthesis of compounds to occur. Trace elements, being good sources of electrons are particularly critical for the absorption of solar radiation and for photosynthesis to proceed orderly at an optimum rate for maximum production of glucose. You can imagine trace elements to be the spark plugs in the engine of photosynthesis. Many different shapes and size of spark plugs, some very small but vital, are needed to fit in and make the engine run efficiently. Leave some out, and it would run like a V8 on 6 spark plugs.
Maximum theoretical yield for wheat has been calculated by scientists to be approximately 15 tons of grain per hectare (1.5 kilograms grain per square metre of land), while in practice, farmers in Europe (UK) have sometimes achieved maximum, attainable, yields of 12 tons per hectare of grain. Certainly very impressive, considering all the factors would be close to optimum to achieve this level of yield; and which gives rise to optimism that there is much room for improvement of yields in Australia. Maximum attainable yield of cereals in Australia is approximately 10 tons per hectare, as some farmers who have followed our recommendations and used sufficient amounts of trace elements and nitrogen have achieved this level of yield. Because of the risk of reduced rain during the seed-fill period, we should realistically aim for maximum economic yield; which should be about 6 tons per hectare in Australia.
Average yields of wheat are however quite mediocre; approximately 1.8 tons per hectare here and about 2.8 tons per hectare in Europe. Its anybody’s guess what average yields are in the USA, Argentina and Canada (our main market competitors for wheat). Because of rising input costs equating approximately to money obtained for 1 ton to 1.5 tons of grain (“break even”), it is no surprise that grain growers are under stress and find it hard to relax their efforts. In recent years crop yield increases have slowed dramatically in both less-developed and developed countries worldwide. source: USDA-ARS, Agronomy Department (Limits to Crop Yield; T.R. Sinclair), University of Florida USA, calling for large increases in agricultural research. An essential feature of such research would be to identify the input resources that are needed for growth of the plant and production of grain (source). Western Fertiliser Technology Pty Ltd is recommending to farmers to concentrate on (in order of priority) applying sufficient trace elements, nitrogen, phosphorus, magnesium, potassium and other nutrients calculated from actual uptake levels from grain targeted to a desired yield (see below).
Heat and light intensity (solar radiation) are climatic factors not lacking in Australia, USA, Argentina and Canada. Europe is not as warm, but has long days of sunshine during the growing season. Our advantage is that we are able to grow hard white, high protein wheats, whilst Europe grows mainly higher yielding, lower protein softer wheats. Quality of air too is not a problem for wheat growing nations, which include China and India. In fact, increasing levels of carbon dioxide in the atmosphere would benefit photosynthesis and plant growth (though not necessarily grain yields). Broadacre crops are usually rain-fed, so rainfall is an uncontrollable factor in photosynthesis unless irrigation is available. That leaves nutrients and microbes; two factors on which we will have to concentrate on if we are to improve photosynthesis efficiency and grain yields for broadacre crops.
Surprisingly, the importance of nutrition for sustainable agriculture or in achieving high (maximum) yields is not always recognised by farmers; arising perhaps from worries about the weather, commitments on expensive machinery and reliance on a diminishing soil resource and minimum fertiliser application for sustenance of crops. Perhaps too, nutrition is viewed by farmers as a complex subject; best left to their farm advisers and fertiliser suppliers. Increasingly though, as agriculture becomes more competitive, and political, with the rapid increase in the price of oil and natural gas, more farmers are now taking a personal interest in nutrition.
In view of your question, perhaps we should enlarge on the relevant laws of nutrition and concepts discussed earlier. Liebig’s law of the minimum states that the yield of any crop is dependent on that particular nutrient which is present in the least, most deficient amount. Blackman’s law of limiting factors states that when a process is governed by a number of separate factors (eg. nutrients, temperature range, light intensity, water-supply), the rate of the process (photosynthesis as discussed here) is limited by the pace of the slowest or limiting factor. Recently, Wallace (Journal of Plant Nutrition, 1986) explained that nutrient stresses do not act independently; yield reduction effects due to departure of several nutrients simultaneously from optimum levels are multiplied, and are serious barriers to obtaining yield maximums. In other words, a serious deficiency of even one minor nutrient costing perhaps a few cents, and environmental stress can have serious effects on plant quality and yield. Wallace’s explanation and calculations of the deleterious effects of multiple nutrient deficiencies on yields can perhaps be viewed as the opposite effect of synergism, where the interaction of nutrients can produce combined favourable effects on yield greater than the sum of their separate effects.
You could calculate fertiliser nutrient needs for maximum yield of wheat and barley grain, by multiplying each nutrient content, from the upper medium range (see; Publications, Grain Analysis) with the desired maximum yield target of eg. 6 tons grain per hectare. For nitrogen, the amount needed would be approximately 122 kg per hectare as nitrogen or 260 kg per hectare as urea (applied at 26 grams per square metre); for phosphorus at 20.4 kg per hectare or 225 kg per hectare as single superphosphate (applied at 22 grams per square metre). The remaining nutrient needs are calculated in the same way in the table below for each element.
Fertiliser rates (approximate minimum) for 6 tons per hectare Wheat calculated from Grain Analysis (see: Publications page)
kilograms/ha | grams/ha | |
Nitrogen (N) | 122 | – |
Phosphorus (P) | 20.4 | – |
Potassium (K) | 36 | – |
Magnesium (Mg) | 8.8 | – |
Sulphur (S) | 8.6 | – |
Copper (Cu) | – | 25 |
Manganese (Mn) | – | 370 |
Zinc (Zn) | – | 180 |
Iron (Fe) | – | 190 |
Boron (B) | – | 33 |
Molybdenum (Mo) | – | 4 |
Cobalt (Co) | – | 0.4 |
A portion of the major and secondary elements, comprising NPK, Ca, Mg and S could be applied before sowing, and a portion with trace elements as liquid fertilisers at 5-leaf and at tillering. Super Energy liquid trace elements can also be used pre-plant with herbicide, and as a seed coating at the rate of 3 litres plus 15 litres of water per ton of seed for vigorous germination and establishment. It can also be used at tillering with a compatible post-emergent herbicide (always do a jar test before use). To calculate the amount of Super Energy needed to supply sufficient trace elements for 6 tons of wheat, divide the grams per hectare needed (eg. 25 grams for copper) with the analysis of copper (6.0 grams per litre). The minimum amount of Super Energy needed to satisfy copper for 6 tons per hectare of wheat grain is approximately 4 litres per hectare.
The nutrient ranges used for calculation of the fertiliser elements in the table above for wheat grain has been drawn from a large number of samples collected over a long period of time and from different locations (see: Publications, Grain Analysis). Nutrient ranges for barley, lupins and canola can be obtained by contacting the Agricultural Chemistry Section of the Chemistry Centre of WA. Alternatively, the minimum nutrient requirements for maximum yield can be obtained for any crop by careful sampling and accurate analysis of grain sampled from a single crop displaying the desired yield per hectare together with quality, eg. 6 tons grain as above. In addition to nutrient requirements, there are of course several other agronomic conditions that need to be satisfied to achieve maximum yield (see: Technical Questions).
Faced with the simultaneous, growing problems of decreasing yields, increasing greenhouse gas, increasing population pressures and declining resources, nations would have to resort to highly sophisticated agriculture. Chemical analyses with powerful instruments such as ICP-MS, which can pinpoint trace and ultratrace elements down to the parts per billion levels, will be needed. Organic chemists, microbiologists and plant physiologists working on elucidation of the metabolism of plants and microbes on the phyllosphere (leaf surface) and rhizosphere (surface and interior of roots) will show the way to increase productive growth of crops and trees, and the means for conserving nutrients. Research on the conversion of simple nutrient forms to biologically useful organic forms for plants by microbes (eg, vitamin B12), for improved metabolism and photosynthesis process in plants would increase.
Restoring forest canopies and increasing growth in globally forested areas with liquid fertilizers, applied with aircraft to fix excess atmospheric carbon dioxide as carbon in trees and forest legumes (free atmospheric N drives carbon sequestration) should become an urgent priority for governments to mitigate climate change. The benefits arising from increasing biodiversity, increasing forest productivity for communities, improved soil conservation and improved water management would easily pay for the low annual maintenance with liquid fertilizers; in addition to the highly efficient carbon sequestration.
Agronomists should work closely with analytical chemists to maintain optimum levels of nutrients in seeds, the first fertiliser package for the plant, and a valuable indicator of nutrient status and fertiliser requirement. Fertilisers from manufacturers should be more complete and formulated to prevent nutrient deficiencies from occurring; to improve utilisation by plants and microbes and improve photosynthesis rates. Farmers will increasingly rely on nutrient data from high yielding fruit and grain crops to obtain optimum levels of the nutrients. If the cost of industrially fixed nitrogen increases, as it inevitably will unless oil and gas prices fall, farmers will increasingly rely on leguminous crops and nitrogen-fixing microbes. Updated: January 27, 2011.
I have planned your wheat program this year in a similar way to last year’s canola program. Grain analysis of your canola should identify any nutrients that are marginal to deficient, which can be adjusted accordingly for the 2008 wheat crop. Your canola sample yielded the following results:
Analysis of your 2007 canola grain
H (High Range)
M (Medium Range)
L (Low Range)
Protein (N x 6.25) | 18.8% (H) |
Phosphorus (P) | 0.47% (M) |
Potassium (K) | 0.59% (M) |
Sodium (Na) | <0.01% (L) |
Calcium (Ca) | 0.34% (M) |
Magnesium (Mg) | 0.30% (M) |
Sulphur (S) | 0.31% (L) |
Iron (Fe) | 40 ppm (L) |
Copper (Cu) | 2.6 ppm (M) |
Manganese (Mn) | 30 ppm (M) |
Zinc (Zn) | 28 ppm (L) |
Boron (B) | 11 ppm (M) |
Molybdenum (Mo) | 1 ppm (M) |
Cobalt (Co) | <0.01ppm (L) |
From the above results, we should place some emphasis on the nutrients sulphur, sodium, zinc, iron and cobalt levels, which falls in the low range for canola (see: Nutrition Management page on this website). The protein level was very good, indicating that nitrogen was not limiting, and phosphorus and potassium were at medium levels.
To plan the inputs for the 2008 wheat crop, a table of the kilograms of major nutrients and grams of trace elements removed by a 4-ton crop of wheat per hectare is given below.
Nutrients removed by a 4-ton crop of wheat (see Grain Analysis, Technical Questions page on this website)
82 kg Nitrogen
13.6 kg Phosphorus
24 kg Potassium
2.1 kg Calcium
5.8 kg Magnesium
5.8 kg Sulphur
124 grams Iron
16 grams Copper
248 grams Manganese
120 grams Zinc
22 grams Boron
2.6 grams Molybdenum
0.24 gram Cobalt
As you have obtained good results using gypsum and dolomite as soil amendments on your farm, we shall continue this practice together with minimal tillage to conserve soil carbon and soil structure. Sea salt is now included in the amendment for pastures and stock.
Coating pre-seeding urea with Soil and Foliar liquid trace elements allows a single pass, as well as helping to prevent volatilization as ammonia if seeding is held up for some reason.
The practice of coating seeds with Super Energy Seed Treatment gives the young plant an early start and vigor as major nutrients and trace elements are available close to it on the seed coat during germination and establishment. This will provide a good start and early root establishment, so important these days from unreliable and patchy rainfall due to climate change.
We will use sufficient granular NPKS fertilizer applied under the seed at seeding time to meet nutrient needs. Remember though, that the soil holds quite a bit of phosphorus as a bank from earlier applications. If your soil test results show a high level of available phosphorus and potassium, you could reduce the amount of DAP and Potash by about 10 – 20%.
Foliar application with Super Trace organic liquid fertiliser and Rich Green liquid nitrogen early at 5-leaf stage allows the establishment of beneficial microbes on the phyllosphere (leaf surface), which helps to antagonize the growth of airborne pathogens thereby protecting the plant from disease (see: Technical Questions page this website; How do microbes fit in with foliar absorption?). Because trace elements in biomass feeds microbes in the soil to increase carbon sequestration and nitrogen fixation, trace elements in fertilisers such as Super Energy Seed Treatment and Super Trace organic liquid fertiliser occupy increasing importance in the new range of technologies needed urgently for reversing global warming and climate change.
So here is your 2008 program for high-protein wheat –
WHEAT PROGRAM (Target yield: 4 – 5 tons/ha. Protein: 12% minimum)
(1) Soil amendments: One to two months before seeding wheat, apply 250 kg/ha Gypsum, 250 kg/ha Dolomite and 100 kg/ha sea salt on the canola stubbles. Amendments are applied each year to subsequent crops and pastures.
(2) Apply suitable pre-emergent herbicide after the onset of rains and weed germinations, before sowing.
(3) Pre-seeding nitrogen: Spread 120 kilograms per hectare of urea (coated evenly with 2 litres of Soil and Foliar Zinc and 2 litres of Soil and Foliar Manganese) a day or two before sowing. Soil should have sufficient moisture for sowing.
(4) Seed Treatment: 5 litres Super Energy Seed Treatment mixed with 3 litres water for each ton of seed. Apply only on the same day sowing commences, together with fungicide if needed.
(5) Seeding: Sow seed with 75 kilograms per hectare of DAP pre-mixed with 75 kilograms per hectare of Potassium Sulphate chips or powder.
(6) 5-leaf stage: Apply through a boom sprayer 10 litres of Super Trace organic liquid fertiliser mixed with 30 litres of Rich Green liquid NS fertilizer.
(For more details on listed products, see Products page on Western Fertiliser Technology Pty Ltd website www.wftptyltd.com.au).
Costing:
Gypsum
Dolomite
Sea Salt
Herbicide
Seed
Urea
Soil and Foliar Zinc
Soil and Foliar Manganese
Super Energy Seed Treatment
Fungicide
DAP
Potassium Sulphate chips
Rich Green liquid nitrogen
Super Trace organic liquid fertiliser
Whether or not to increase farm size to increase income is a complex issue for most farmers under pressure from increased input costs of fertilisers, fuel and chemicals.
The net income of your farm is governed by the relationship: Net Income = Area x Yield x Price (Grain and Wool) – Input Costs From above, it can be seen that the income multiplying factors are Area (A), Yield (Y) and Price (P) whilst input costs (C) reduces income. In an ideal farm economy, one should strive to achieve maximum attainable A, Y and P with the lowest possible costs, but in the real world this is seldom achieved. Unless governments are vigilant, a worst-case scenario for farmers of low yields, low prices for produce and high input costs could develop, setting back efforts to slow global warming by increasing farm-based biosequestration of carbon dioxide.
To help you to decide, we can briefly examine each income affecting factor and try to optimize them so as to achieve improved profitability and increase net income from your farm.
AREA
There is an excellent correlation between larger farm size and increased income for farmers, and generally, farm size increases with the level of economic development in countries. In the past decades, average farm size has increased in Australia in line with other high-income countries. Increased farm size allows fixed costs and overheads to be spread over a higher level of production. The trend in Australia indicates a consolidation of operations with fewer farms but the same amount of farming land around 769 million hectares.
There is a high percentage (70 -90%) of farms with areas less than 5 hectares in most parts of the world which includes Asia, Africa, parts of Europe, and Latin America. In this respect I would consider your farm to be fairly large, so you should have much scope for increasing your income with improved productivity management.
A new and early trend in Australia is for some farmers to “get big†by cropping massive areas of 80,000 to 100,000 hectares. Whether or not this is a good strategy only time will tell. Success would depend on favorable weather, tightly-controlled financing, steady or increased prices for cereals, legumes and canola, close supervision of operations, moving expensive and large machinery where needed, and most importantly, getting the nutrition and cropping technology right. As the size of the farm increases beyond an optimum size the risks increase remarkably and it can be stressful waiting for rain at critical times or in trying to avoid leaf disease and damaging frosts. Climate change could increase risks as normal seasons have turned into hard-to-predict seasons.
By spreading the cropped area over a very wide area, farmers hope to reduce the risks from inadequate or untimely seasonal rain or frosts in a particular area. Agricultural technology to improve fertiliser and water-use efficiency, together with improved nutrition to lower risks is particularly critical for a large farm. As area (A) is a multiplying factor, even small improvements in yield from improved nutrition of crops can significantly increase income from a large farming enterprise.
As small farms greatly outnumber large farms globally, the challenge to governments is for helping farmers adapt technologically to changing climates. Financing sustainable practices in small farms is increasingly important as economies of scale are absent, and has to be made up by substantial increases in productivity. Concentrating on rural economic development of small farms is urgently needed now to address developing food security problems in many countries.
YIELD
This website has often underlined the importance of improving photosynthesis, the process by which green plants use the sun!s energy to build up food reserves for the seed . For cereals and legumes, part of your enterprise, improvements in nutrition management, better seeds and varieties, efficient tillage and pest control result in improved photosynthesis and an increase in the harvest index (HI). Harvest index is the ratio of the weight of seed to the total weight of mature plant at harvest. Increasing yield therefore depends on increasing both crop biomass (small petite plants don!t do much for yield) and the harvest index, which for wheat should be approximately 50% of biomass.
Grain legumes such as lupin and field peas in your rotation helps to maintain soil fertility and increase the N economy of soils to counter rising costs of fertiliser N. Lupin crops also provide a disease break for cereals and produce more dry matter (carbon) due to high vegetative growth. However growing lupin crops has been less rewarding because of low harvest indices of 0.43 – 0.25 or less, which is usually obtained for forage type legumes such as vetch. Harvest indices for lupin grain has a potential of 0.50 – 0.60, indicating a need for improved nutrition and monitoring nutrient sufficiency through grain analysis.
Wide-row trials (50 cm) for lupin crops by the Dryland Research Institute (source: Department of Agriculture and Food, Western Australia; R J French and M Harries, 2007) has found improvements in harvest index from improved water supply at seed-fill for average seasonal conditions. Other benefits of wider spacings for lupins could be improved interception of solar radiation by developing green pods and less humidity in the crop canopy discouraging disease development. For substantial increases in yields of lupins, I recommend use of 50 cm rows and superphosphate blended with potassium sulphate, granular magnesium sulphate and some sea salt (Dampier Salt) at seeding, plus foliar-applied trace elements as Super Trace or Super Energy.
Preventing deficiencies and improving nutrient balance with grain analysis improves the proportion of photosynthesis products partitioned to the seed; sink capacity is increased with less shedding of flowers for cereals, legumes and canola leading to increased numbers, size and weight of seed which increases harvest index and yield. Visual indicators of improved nutrition are increased stay-green of biomass, large and tenacious flowers, and increased immunity of plants to environmental and biotic stress.
Inadequate nutrition leading to poor water-use efficiency are large contributory factors to low yields as, contrary to expectations, some farmers in higher rainfall areas are harvesting lower yields than some farmers in dryer areas. Water-use efficiency of crops in broadacre dryland farming can be improved markedly by using balanced fertilisers together with carefully integrated management packages. If your yields are district average or lower there is much scope for improving your income.
Fertiliser wastage should be avoided due to the sudden and large increase in prices, and increasing fertiliser efficiency is paramount for reducing costs by increasing productivity. For example, let us look at DAP (diammonium phosphate) granular fertiliser that you use for seeding cereals. Although a high analysis source for N & P, ordinary DAP lacks critical sulphur as well as potassium, calcium, magnesium, chloride and trace elements. Sodium is an important element too for your clover based pastures and forage legumes. An integrated fertiliser management package you could consider with DAP fertiliser is discussed in the section above for wheat, which includes the soil amendments dolomite (MgCO3.CaCO3), gypsum (CaSO4.2H2O) and use of potassium sulphate, sea salt and seed and foliar-applied liquid fertilisers. Liquid fertilisers can be used for coating the granular fertilisers DAP, superphosphate or urea with trace elements at seeding time, improving root growth.
Planned nutrition is vital for productive pastures, atmospheric nitrogen fixation by clovers and wool quality together with improved health of sheep. Superphosphate plus potash fertiliser routinely used for pastures is remarkably improved by use of liquid Super Trace or Super Energy which supplies trace elements to improve pasture growth and seed-set.
PRICE and COSTS
Without needing to elaborate, income is highly dependent on the prices farmers obtain for their produce. Prices change according to supply and demand, growing conditions around the world, marketing systems in use and increase in input costs. Recent rises in food and grain prices (wheat, rice, corn, soya bean, canola) reflect increased costs of production and lower global reserves. Counting on high prices to support income is a risky strategy for the longer term. Relying on increased yield and quality to improve income is a better strategy. Keeping up-to-date with technology improvements is therefore crucial for increasing farmers! incomes.
Markets for wheat, barley, rice, canola etc is highly competitive between nations, and nations who quickly adopt and disseminate new technologies of production locally increase supply which tend to drive down prices when demand is lower. Technologyefficient nations with high productivity can afford to market at lower prices, whilst nations with lower productivity and production volumes are less able to compete on price. The U.S.A, Canada and leading countries in EU has seen remarkable improvements in yields of cereals in the past decade. Cooperation and helpful sharing of information among farmers themselves is of great importance. In Australia there is a move by big growers to amply increase on-farm storage of grain, enabling savings and more profitable marketing decisions as well as gaining a better price for their quality produce.
An existing worldwide problem is the low yields of legume crops, when compared to the common cereal crops. Legumes such as the common bean are an important part of the diet in developing countries, providing many health benefits. In developed countries, the emphasis on growing continuous crops of cereals needing large amounts of nitrogen fertilisers is facing severe constraints due to rising costs (source: Agronomy Department, University of Florida, USA; T.R. Sinclair: Increasing yield potential of legume crops – similarities and contrasts with cereals).
The answer to your question lies in understanding the marked differences in the physiology and nitrogen metabolism of legumes versus the non-legume cereal crops wheat, rice, barley, oats, and the other economically important non-legume crops potato, canola, sugar etc.
The legume or the pulse family of plants is economically second only to the grasses, providing nutritive foods to man and animals because of the high-energy food stored for the plant embryo in the seed. The pulses are a large family, composed of approximately 650 genera and 17,000 species. Legume foods are rich in protein and sulphur amino acids, and are an indispensable source of the minerals phosphate, potassium, calcium, magnesium and the important trace elements; and are often used as meat substitutes for people in less developed countries. Pulses provide rich forage and fodder for animals, and have a vast array of uses as fibres, flavourings, perfumes, and as insecticides. The organic forms of the nutrients in dry matter makes legume crops (eg. clovers and lupins) particularly desirable as green-manure to raise the nitrogen, organic matter content and fertility for the following cereal and other crops. Most legumes however have a low tolerance of salt, which reduces yields.
Grain analysis (see: Technical Questions) is a valuable starting point to examine the different physiological needs of legumes, cereals and oilseeds. Plant growth has the sole purpose of preparing a source of suitable food in seeds for the establishment and growth of the embryo. An analysis of the contents of the seed should reveal the differing physiological and nutritional needs of the young plant.
The key advantage of legumes is their ability to form symbioses with specific bacteria in the root nodules, which can fix nitrogen from the air into organic nitrogen compounds for conversion into protein by the plants. In return, plants provide food to microbes as carbohydrates from photosynthesis in leaves and stems, and minerals absorbed from the soil. Indeed this amazing cooperation between plants and microbes is the reason for the seeds (fruits) of legumes to be a rich source of proteins, carbohydrates and minerals. Clover-based pastures have been the chief support of nutrition for the livestock and wool industry in Australia. In addition, rotation of crops with pastures allows the build-up of nitrogen and valuable organic matter to improve soil structure and fertility for the following crops. Sustainable agriculture would be impossible without the contribution of legume plants.
In the table below, an analysis of the nutrient contents of barley, canola and lupin seeds are shown. The analyses are the average concentration levels of samples received and analysed at the Chemistry Centre of Western Australia over a long period of time, from different locations in the State. The low to high ranges for lupin seed is also shown.
| ————————-% as received———————— |
| ————————-ppm as received———————– | ||||||||||||
| Protein | P | K | Na | Ca | Mg | S |
| Fe | Zn | Cu | Mn | B | Mo | Co |
BARLEY | 10.9 | 0.18 | 0.41 | 0.02 | 0.03 | 0.11 | 0.13 |
| 39 | 13 | 2.5 | 17 | * | * | * |
CANOLA | 14.5 | 0.51 | 0.64 | 0.01 | 0.34 | 0.30 | 0.53 |
| 50 | 36 | 2.7 | 26 | 11 | * | * |
LUPIN | 34.0 | 0.34 | 0.84 | 0.04 | 0.24 | 0.18 | 0.24 |
| 33 | 28 | 3.3 | 16 | * | * | * |
low – | 26 | 0.18 | 0.57 | 0.01 | 0.14 | 0.14 | 0.16 |
| 20 | 11 | 1 | 4.2 | * | * | * |
high range | 48 | 0.63 | 1.66 | 0.11 | 0.46 | 0.30 | 0.34 |
| 110 | 46 | 6.9 | 76 |
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Symbiosis begins when rhizobia in the soil gains access to the interior of legume roots via infection threads, forming nodules. Inoculation of the seed with suitable rhizobium strains therefore increases nodule numbers and yields. The internal structure of the nodule is designed as an extremely clever and efficient chemical factory, both to house the bacteria, and conditions to produce ammonia efficiently and convert it to organic N compounds for the plant. Legumes produce nitrogen compounds with a ureide (urea) and/or an amide (amino or ammonia) type structure. Ureides are transported to plant parts via meristematic tissue, and amides travel via the phloem. Legumes that transport ureides via the xylem, such as soybean and cowpea, are very sensitive to soil drying (source). Soil drying effects are countered in the lupin and alfalfa (lucerne) legume plants by the possession of deep root systems.
In return for the fixed N compounds, plants feed the bacterial colonies with energy in the form of sugars and carboxylic acids produced by photosynthesis. This chemical energy is utilised to convert atmospheric nitrogen gas into ammonia and then to N compounds.
The chlorophyll molecule, activated by magnesium is central to the photosynthetic responsibilities of the plant, whilst the high molecular weight enzyme, nitrogenase, activated by iron and molybdenum is central to the nitrogen-fixing responsibilities of the bacterial nodules. The nitrogenase complex is very sensitive to atmospheric oxygen, which can deactivate it. To prevent deactivation of nitrogenase, the plant produces a special form of hemoglobin called leghemoglobin, containing iron. This protein has a high affinity for binding to and transport of atmospheric oxygen, much like our own blood hemoglobin. In fact, it has a pink-red colour too.
Farmers who want a high harvest index and yield from the legume plants, should therefore ensure that plant and bacteria are supplied with adequate magnesium, suitable types of iron compounds for availability, molybdenum and other nutrients.
Nitrogen fixation in legumes require phosphorus (P) in reasonably large amounts compared to cereals, to sustain the high energy flow pathways as ATP (adenosine triphosphate), including trace elements as sources and acceptors of electrons. Oilseeds such as canola also require high phosphate for the formation of phospholipid compounds for cellular membranes. The physiology of legumes is therefore markedly different to that of cereals and canola, so fertilisers that contain sufficient phosphorus, magnesium, and trace elements and ultratrace elements are needed for productive growth. In addition, potassium is needed for buffered control of pH in cellular reactions, together with sufficiently high amounts of sulphur for the production of various sulphur compounds (eg. cysteine, cystine, methionine, glutathione etc.) involved in biosynthesis reactions. Boron and cobalt are often forgotten in fertilisers for legumes despite being components in the synthesis of carbohydrates and vitamin B12 by plants and bacteria respectively. Boron is also a vital nutrient for canola for a premium oil content in seeds.
In the table above, you can also see that calcium and magnesium are important components of lupin seed. Calcium and magnesium are needed in biosynthetic pathways of polymerisation and for enzymatic functions, and this is borne out by the analysis values of lupin compared to barley. Supplying organic forms of calcium by the seed resource to bacteria would encourage early colonisation. Calcium and magnesium ratio (1: 0.5) in fertilisers is close to ideal. The low to high nutrient ranges for the lupin legume seed in the table may shed more light on its physiology. Manganese is a particularly important trace element for all legumes including lupin, and also canola, for photosynthesis in the chloroplasts of leaves and stems.
Although the leguminosae are capable of fixing atmospheric nitrogen for growth and development, timed and judicious applications of ammonium sulphate at sowing assists crop establishment, provided balanced fertilisers and trace elements have been used. Nitrogenous fertilisers should not be used however where delayed ripening must be avoided on account of an unfavourable climate. At the pod-filling stage, liquid fertiliser as a mixture of Richgreen N-S and Super Energy has been found to increase the number of seeds per pod and pod length. Generous applications of phosphate and sulphur liquid fertilisers together with potassium and trace elements accelerate ripening in regions with a short growing period. Regular applications of Liquid Lime and Super Energy will markedly improve the productivity of pastures.
*For wheat yield targets lower at 2 – 2.5 tons/ha, the inputs above can be halved for economy.
The term NPK mentality was coined many years ago by influential agricultural scientists of the day, who believed more in the productivity of organic composts and manures than chemical type NPK fertilisers. They believed that the organic forms of nitrogen, phosphorus and potassium in organic fertilisers were preferred by plants to inorganic forms, when in fact it is probably the slow degradation and slow release of plant nutrients in organic matter that gives organic matter its fertilising value. Plants and microbes convert simple inorganic nutrients to valuable assimilable organic forms for humans and animals. While there is no doubt today that organic matter is the most important component of a fertile soil, inorganic chemical NPKS fertilisers are still the prevailing source of the major nutrients for agriculture, especially broadacre. Other leading agricultural scientists wanted to place less emphasis on NPK ratios, which often came at the expense of lower or absent secondary nutrients calcium, magnesium, sulphur and trace elements in the formulations. In reality, NPK ratios are still widely used today to indicate analysis values of fertilisers and for preferred use with certain crops. A step forward for everyone could be for manufacturers to include too the percentages and ratios of the secondary elements, eg. 10:10:10:1:1:2 fertiliser.
Historically though, the term PNK mentality should be more correct, as this would trace the development of inorganic fertilisers. Bones (animal and human) and guano were the main source of phosphorus for earlier agricultural production before the advent of superphosphate. In an historical and far reaching address to the British Association of Science in 1840, Justus Von Liebig, a German analytical chemist, proposed the production of rapidly available phosphorus from bones, as mono-calcium phosphate instead of the di- and tri-calcium phosphates present. This led to the production of superphosphate by John Bennett Lawes, who treated a local phosphate ore with sulphuric acid, and which subsequently led to a huge expansion of food production (and population) for the world. Production of cereals such as rice and wheat were still limited then by the need for sufficient nitrogen, until the advent of industrially fixed nitrogen led to a surge in the popularity of P&N fertilisers such as superphosphate and ammonium nitrate. It was later discovered that the third major nutrient element, potassium, added to the mix as potassium nitrate (saltpeter), improved production of staple crops even further. Other fertiliser compounds, eg. ammonium sulphate, ammonium phosphates, potassium nitrate, potassium chloride, urea, potassium phosphates; together with the secondary element compounds as calcium nitrate, magnesium sulphate, magnesium nitrate, magnesium ammonium phosphate (magamp) etc. followed in time. Since then, agricultural scientists have experimented with many different formulations providing different NPK ratios for both granular and liquid fertilisers, and have found that some plants respond better and provide higher yields according to the nutrients in certain ratios. Although a wide variety of NPK fertilisers are available with different ratios, they are composed of seven basic types:
NPK ratio | Type | Example |
1:1:1 | Balanced | 15:15:15 |
2:1:1 | N rich | 20:10:10 |
1:2:1 | P rich | 10:20:10 |
1:1:2 | K rich | 10:10:20 |
2:2:1 | NP rich | 16:16:8 |
2:1:2 | NK rich | 16: 8:16 |
1:2:2 | PK rich | 8:16:16 |
The use of various NPK ratios depends on the crop grown. For example, NP rich ratios are popular in Australia for broadacre crops as Australian soils are inherently poor in phosphorus. NPKS and trace elements use for cereals is slowly increasing as the awareness of the importance of K and trace elements to crop quality, yield and resistance to environmental stress (frost and drought) increases. PK rich ratios plus trace elements are used more often for legume crops than the NK rich ratio, the latter being popular for fruits. Where single elements such as N, P or K need to be boosted at certain growth stages, N rich, P rich or K rich formulas are often used.
A fertile soil is able to provide all the nutrients that a plant needs for productive growth in balanced proportions. An absence of the secondary nutrients and trace elements in NPK fertilisers could therefore lead to deficiencies and low yields. Another problem often encountered is a deficiency of calcium and sulphur in NPK fertilisers when high analysis phosphate fertilisers such as MAP (mono-ammonium phosphate) and DAP (di-ammonium phosphate) are used. These products are produced from the reaction of ammonia and phosphoric acid. If elemental sulphur is then added as a source of sulphur in the fertiliser, lime should be used to prevent a reduction in soil pH in the root absorption zone (rhizosphere). Liquid and granular NPK fertilizers containing calcium, magnesium, sulphur and trace elements are aptly called premium grade fertilizers (e.g. 10:10:20:1:1:4 + TE); they are usually more expensive but perform a lot better than straight NPK products as shown in above examples.
Liquid fertilizers with the same concentrations of nutrients as granular fertilizers are more economical to use as the trace elements in the liquid fertilizers are chelated, with organic components added in solution for enhancing microbial activities. An important advantage of liquid fertilizers is their suitability for direct aerial application to the foliage (phyllosphere) where photosynthesis occurs. The nutrients and photosynthates are then translocated from the leaves via the phloem to the roots, which increases their activity for absorption of nutrients and water, leading to increased growth.
There is an enormous waste of energy resources today in the world arising from the use of unbalanced NPK fertilisers, probably amounting to many billions of dollars annually. Unfortunately with nutrients there is not much room for error; as discussed earlier, a severe deficiency of a single element or multiple elements coupled with environmental stress could result in crop failures and a huge waste of investment in labour and resources. Fertiliser use efficiency arises from the promotion of the photosynthesis process for the production of plant resources, such as protein, starch, sugars, vitamins, fibre, oil, cellulose etc. All nutrients are closely involved in the photosynthesis process; yield and quality being affected if there are deficiencies present. Reduced quality for cereals may mean shrivelled grain, low protein content or poor dough qualities. For fruits it could mean small size, poor taste and colour, and a short shelf life.
Grain and tissue analysis can be used to identify limiting nutrients. As the quality and quantity of protein together with yield relies on the availability and overall metabolism of nitrogen, nitrogen use efficiency can be a good measure of the overall nutrient balance and fertiliser use efficiency. This can be measured quite easily; and in the case of cereals, would involve comparing applied N versus N uptake in grain and straw. An N-uptake index of approximately 50% only (0.5 instead of eg. 0.8) could mean that the fertiliser is unbalanced in nutrients or that nutrient deficiencies are occurring, and that photosynthesis efficiency is not optimal. Other management factors may also be responsible for the poor utility of applied nutrients by crops, and these should be identified and corrected.
A modern view in crop management is that the mode of action of inorganic NPK type fertilisers should emulate those of the desirable organic fertilisers such as stabilised composts, animal manures and plant- based green manures. The properties of organic fertilisers are too numerous to discuss fully here, but their main properties are:
A high cation exchange capacity.
A high water holding capacity.
Balanced nutrient contents with slow-release properties.
Favourable interactions with the nutrient elements improving availability, notably nitrogen, phosphorus, iron, copper etc.
A perfect habitat for beneficial microbes and earthworms, which improves soil structure and reduces the spread of disease organisms.
Although ideal as fertilisers, the main disadvantage of organic composts and manures are their relatively low nutrient levels compared to high analysis NPK fertilisers. The amounts of nutrients taken up by a four to six-ton crop of wheat for example (see also technical questions) would require several tons of compost or manure per hectare, making it nearly impossible for broadacre cropping systems. Ideally of course, organic fertilisers should, whenever possible, be used together with NPK and trace element fertilisers for high productivity; and this practice is often adopted by cereal farmers with small farms, eg. in China and India, where productivity has improved greatly in the past decade. In Australia, farmers strive to increase the organic matter in soils by growing pastures with clovers and rotation with legume crops.
The flexibility of formulations containing secondary elements as ideal compounds, high NPK nutrient analyses together with trace elements and good chelation abilities means that liquid fertilisers can come close to or even surpass the performance of organic fertilisers. Stimulation of microbial activity can be easily provided by the use of fish emulsion in liquid fertilisers. Together with the qualities of ease of application, accurate, timely and even application plus the avoidance of segregation problems, the popularity of liquid fertilisers with farmers are set to increase dramatically within a decade. Updated: March 5, 2011.
Under Technical Questions in Grain Analysis, 4 tons of wheat grain was found to contain approximately 0.12 gram of iodine per hectare. This is a very small amount to replace per hectare. Why do plants need such small amounts of trace elements, but large amounts of nitrogen (82 kg) and phosphorus (13.6 kg) per hectare for grain?
Iodine is a micronutrient known also as an ultratrace element needed in very small amounts. Manganese, iron and zinc are needed by plants and animals in larger amounts and are referred to as the major trace elements (see: Table of grain analysis – Nutrients removed in 4 tons per hectare of wheat grain). Trace elements perform their vital functions as coordinated atoms in ordered locations activating complex high molecular weight enzymes and proteins. For example, the iron and molybdenum containing enzyme nitrogenase of legumes, which catalyses the reduction of molecular nitrogen to ammonia for use by plants, contains just one atom of molybdenum at the active site of each molecule of nitrogenase enzyme. Nitrogen and phosphorus takes part in both enzymic and structural functions (as proteins and nucleic acids), and are therefore required in much larger amounts than the trace elements. Balanced fertilisers are formulated by scientists to reflect as closely as possible, the relative abundance of the nutrients in plants.
From Avogadro’s Number, we can calculate, for example, the numbers of iodine atoms in 0.12 gram of iodine. Avogadro’s Number shows that there are 6.022 x 10 (to power of 23) atoms of iodine in 126.9 grams (one mole) of iodine. This gives 1.424 x 10 (to power of 14) atoms of iodine in each gram of wheat grain in a 4-ton crop removing approximately 0.12 gram of iodine per hectare. For nitrogen, 8.818 x 10 (to power of 20) atoms are present in each gram of wheat grain in a 4-ton crop removing 82 kg per hectare of nitrogen. The major trace elements such as iron, manganese and zinc are needed in larger quantities per hectare for wheat grain (124grams, 248 grams and 120 grams respectively). Similar grain analysis data for rice, corn, sorghum etc. would be very useful in calculating fertiliser needs for maximum or economic yields. Universities and agricultural extension services should be able to provide these data to farmers and agronomists.
Terrestrial plants and animals are descendants of marine organisms, which evolved in the ocean (the primordial soup) and as such need a diverse range of nutrients for productive growth. This is reflected in the use of seaweed (kelp) and fish emulsion in some fertilisers as seawater contains all major and trace elements needed for nutrition. High analysis, purer forms of phosphate fertilisers such as MAP (mono-ammonium phosphate), DAP (di- ammonium phosphate) and 85% phosphoric acid contain less trace elements as trace elements are partly removed during the production process, so would benefit from supplementation with trace elements.
As analytical instruments and methods improve, with lower limits of detection, scientists have been adding to the list of trace elements needed by plants and animals, together with increasing abilities to identify nutritional problems. Trace element deficiencies due to suboptimal intake of a specific trace element are more likely to be seen as pathological effects when the organism is under some nutritional, metabolic or physiological stress (source: F H Nielsen; USDA, Agricultural Research Service; Grand Forks Human Nutrition Research Centre, ND, USA).
A report launched by the UNICEF and the Micronutrient Initiative offers a global overview of vitamin and mineral deficiencies – a public health issue that prevents a third of the world’s children from reaching their intellectual and physical potential. According to reports (UNICEF Press centre) unless action against vitamin and mineral deficiencies moves into a new level, the developing world’s children will remain at risk and the UN will not achieve its goals of eradicating extreme poverty, improving maternal health and reducing child mortality by two-thirds by 2015. For example, iron deficiency impairs intellectual development in young children and is lowering national IQs. Iodine deficiency in pregnancy is reported to be causing as many as 20 million babies a year to be born mentally impaired. Quality sea salt used in cooking is a cheap but valuable source of trace elements (eg. iodine) and minerals (eg. magnesium). Sea (ocean) salt of good quality should be made widely available in and its regular use encouraged at health clinics.
In addition there is a pressing global need to reverse high atmospheric carbon dioxide levels and mitigate global warming through various means ( see: Carbon dioxide and water management above) including improved photosynthesis and water use efficiency by forest plants, crops and by microbes in soils. As discussed earlier, adding trace elements to fertilisers to improve photosynthesis rates should be a very important consideration during manufacture by fertiliser companies, and their use fostered by national governments.
Foliar application of liquid fertilisers to the surface of leaves directs trace elements quickly to the site of photosynthesis where they are needed to fix carbon dioxide and water as carbohydrates. It is probable, though not yet shown because of complexity, that trace elements improve photosynthesis by increasing the efficiency of rubisco (ribulose-1-5-biphosphate carboxylase), the key enzyme in the Calvin -Benson Cycle. Foliar application of organically chelated nutrients are needed as some of the trace elements have poor phloem mobility to reach leaves in adequate amounts when needed, as well as the long distances involved from the soil and roots to the surface of leaves.
Would sea salt make a good fertiliser?
Quality sea salt used in moderation with other nutrients would markedly improve the function of most fertiliser products. Sodium, chloride and potassium are three nutrients which work well as a team. Potassium being an important nutrient element in NPK fertilisers makes sodium (Na) and chloride (Cl) from sea salt important nutrients too. Inadequate or deficient levels of salt in soils or fertiliser can lower quality and productivity of crops. Sodium and chloride as nutrients for terrestrial plants are unique in that they occupy the niche area between major and trace elements.
Salt is almost always added to our food, but as a nutrient for plants the salt content is often forgotten altogether in fertilisers. Not all soils suffer from excess salt, and because native sodium chloride in soils is so soluble, it is often leached beyond the reach of most shallow-rooted crops. Adequate sodium and chloride in balanced fertilisers improves the colours, taste, texture and keeping qualities of fruits and vegetables.
Sodium as sodium nitrate (Chile saltpetre) was used as a nitrogenous fertiliser for cereals and other crops before industrially fixed nitrogen as ammonium sulphate, ammonium nitrate and urea became available. When they did, use of sodium declined which was unfortunate in light of its important position in nutrition. Use of chloride continued as potassium chloride. From recent grain analyses of wheat, oats, barley, legume grains (field peas, lupins) and canola, the levels of sodium, in relation to potassium and magnesium appears to be too low. Sodium borate (borax) in fertilisers provides some sodium, but it is used in quantities sufficient for boron but not sodium. Sugar beet is responsive to sodium fertiliser and is essential for maximum sugar yield. However, sodium fertiliser should always be used together with potassium fertiliser and not on its own (source: carrs-fertiliser.co.uk/beetchoice). Based on the good response of sugar beets to sodium containing fertiliser, sugar cane too would probably respond well to adequate sodium.
Sea salt contains useful levels of important trace and ultratrace elements such as zinc, copper, boron, iodine, selenium, bromine etc (reference: The Trace Elements and Man; HA Schroeder (1978); source: FH Nielsen, European Journal of Nutrition, 39:62-66 (2000), Steinkoff Verlag Darmstadt). The environment in which living organisms evolved was apparently a primary determinant of which elements became essential for life (Schroeder and Nielsen).
Chemically, sodium chloride and potassium chloride are mineral salts known as electrolytes which readily dissociates into positive and negative ions in water, highly capable then of conducting electricity, and importantly for physiology and photosynthesis, helps to move electrons. The sodium/potassium balance across a cell’s membrane creates an electro-chemical gradient known as the membrane potential. An ion-pump is thus formed across the membrane, energised by ATP-based enzymes. The sodium/potassium ionic pump of each cell pulls in nutrients when needed and pushes out waste according to the controlled cell membrane potential, membrane permeability and cellular pH.
In animals, close control of cell membrane potential by sodium and potassium ions is critical for nerve impulse transmission, muscular contraction and heart functioning (source: Linus Pauling Institute; Micronutrient Research for Optimum Health, Oregon State University, USA). Excessive sodium should not be used for both plants and animals because this upsets the sodium/potassium balance across cellular membranes.
In plants, the conductive properties imparted by dissolved sodium chloride in water improves electron delocalisation and electron mobility in large organic molecules such as enzymes, lowering activation energies and improving efficiencies of redox reactions involving active-site trace elements. As many key enzymes such as rubisco are intimately involved in photosynthesis and with most enzymes containing trace elements at active sites, adequate sodium, potassium and chloride promotes photosynthesis.
Organic matter in soil has a high ion exchange capacity and retains sodium and chloride together with potassium on exchange sites for the benefit of plants and microbes. Improving growth of legumes can address the decline of organic matter in soils. Supplementation of balanced fertilisers with sea salt will improve nutrients uptake by roots for improved quantity and quality of crops including legumes. Microbes in N-fixing nodules of pasture legumes need adequate salt for nutrition, thereby making better use of soil phosphate and improving phosphate availability for following crops. Optimum levels of sodium needed are approximately 1/15th to 1/10th that of potassium, and 1/4 to 1/2 that of magnesium. The rates per hectare of sea salt added to foliar and granular fertilisers are approximately 0.5 kg/ha (foliar) and 2 kg/ha (soil). Application rates can be fine-tuned by Grain Analysis to keep Na/K, Na/Mg and Na/Ca ratios at an optimum; particularly important for microbes in legumes for carbon and nitrogen fixation.
Carbon sequestration by plants through improved photosynthesis and carbon fixation in soils by microbes is increasingly important to mitigate global warming problems. Seawater is quite low in iron concentration, and some scientists have suggested addition of iron salts to the surface of seawater to encourage rapid growth of plankton and increase carbon sequestration. Although low in iron, seawater is a highly productive medium for growth. Should we upset the ecological balance of seawater by addition of iron to seawater? Rejuvenation of existing forest covers around the world and growing new trees (quickly) would be a better solution for buying us time as the production of extra wood for building homes would offset the cost of fertilisers. Globally improving photosynthesis on leaves of trees and crops, and increased forestry is a proven technology that is simple to transfer. Applied intensively and extensively worldwide, it can reduce atmospheric CO2 concentrations rapidly while producing oxygen. Simple calculations of atmospheric CO2 levels (380 ppm/v) and the amount of carbon in wood needed to reverse CO2 concentrations should prove this to be true. A leaf is a wonder of creation, harnessing solar energy and combining carbon dioxide and water chemically to form carbohydrates as food or wood while producing oxygen; all this at ambient temperature. To manufacture just a single functioning leaf would cost thousands of dollars, if at all possible.
Feeding CO2 from power plants to algae in large tanks containing nutrients from sea water, for conversion to biodiesel is an excellent idea (see: MIT addresses global warming: ZDNet). A fuel for transport is formed here, rather than direct burial of liquid CO2 at sea. A globally balanced and sustainable system to mitigate excess atmospheric CO2 is needed which takes into account precious oxygen. Resources are hydrogen from coal, and oxygen from trees, crops and algae for the clean-burning fuel producing benign water; and electricity from solar radiation. Carbon left over after removal of hydrogen from coal and fossil fuels can be used for road surfaces and for building materials (source: Carbon Sequestration Focus Areas; Office of Science, Germantown, Maryland, USA).
The annual increase of 1 – 2 ppm of CO2 in the atmosphere becomes alarming if calculated as increased molecules of CO2. As more molecules of CO2 pack into a cubic metre of airspace, is the insulating blanket of greenhouse gas becoming super efficient at hampering radiative heat loss into space from the planet at night, worsening high day-time temperatures causing heatwaves? These are questions that scientists need to answer in order to keep the public informed in the global race against global warming.
Why is biomass important? How can we grow biomass more efficiently?
When biomass is grown as an energy conversion crop or as food, carbon dioxide from the atmosphere is captured. Agricultural crops, forest residues, grasses and algae, are important feedstocks for the biomass industry. More efficient ways to increase quantities of biomass at harvest are needed, and to improve water and fertiliser-use efficiencies for growing biomass.
Liquid fuels derived from thermal processing of coal and biomass (US Department of Energy; Office of Science, Brookhaven National Laboratory; Meyer Steinberg, Hydrocarb Process) are now undergoing rapid development. Today’s biomass uses include conversion to biodiesel, ethanol, hydrogen, biomass power, industrial process energy and to chemicals (ref: US Department of Energy; Energy Efficiency and Renewable Energy). Biomass grown intensively worldwide offers our best hope of sequestering high atmospheric CO2 rapidly and to reverse present day levels of CO2 to lower levels, perhaps to 1960’s levels of CO2 (see: USE OF NOAA/ESRL/GMD DATA). The monthly variations of CO2 levels in the atmosphere throughout the year gives an indication of the amount of CO2 emitted into the atmosphere; the levels being significantly lower when crops and trees are actively growing and capturing CO2. A massive increase in planting of biomass globally should drive down CO2 levels quickly.
Reducing fossil-based emissions of CO2 to the atmosphere by quickly updating technology and growing biomass energy extensively to reverse CO2 levels to safer levels, are global imperatives. There are extraordinary similarities between global warming and the Titanic tragedy. Had the Titanic (a technological marvel of that time) been travelling more carefully in dangerous waters, and had it reversed its engines a minute or two earlier, it could have just missed the iceberg and saved the lives of its passengers.
Legume plants and trees are grown for forage eg. Gliricidia sepium (FAO, Agriculture Department; T.R. Preston; Integrated Farming Systems for the Wet Tropics) and Leucaena diversifolia and L. trichandra; (University of Hohenheim and CIAT; Field characterisation of the forage tree legumes; Katrin Zofel et al; Tropentag 2006, Bonn, Germany). Four months after transplanting seedlings of Leucaena into the field, plant height and width were up to 2.3m and 2.4m respectively. Plants indicated good vigour and absence of pests and diseases (Zofel et al). Tree legumes occupy favourable and promising positions for growing biomass efficiently and cheaply. Nitrogen fertiliser is an expensive input in agriculture and forestry, making the atmospheric source of nitrogen through biological fixation increasingly attractive (see: Nutrition Management: Legumes).
Enzymatic processes for conversion of biomass to fuel ethanol prefer sources with high levels of sugars, starch and cellulose with lower protein nitrogen. Non-legume biomass sources for enzymatic ethanol production are sugar cane, corn grain and stover, wheat, sugar beet, cassava, potato, etc. A large amount of information on the benefits of growing legume and non-legume crops and trees for biomass is available on the web.
With climate change and droughts spreading around the world, there is an urgent need to establish new forests quickly and to maintain their rapid growth. Fertilisers applied at establishment and at intervals thereafter as liquid fertilisers should provide the answer. Soils suitable for growing new forests usually have ample supplies of potassium, calcium and magnesium for longer-term growth. However during the early and vital establishment phase, providing the plant with ample NPK nutrients, secondary and trace elements would improve root growth allowing the plant to access water at depth and dramatically shorten the time from planting to harvest. Applying fertiliser is therefore a valuable investment, which reduces the overall cost and provides high returns. Importantly, with less reliable rainfall and drought occurring, nutrients from fertilisers improves physiological water-use efficiency for the production of biomass. Nutrients are the driving force in photosynthesis for combining water and CO2 to produce sugar, protein and cellulose. Inadequate nutrients would mean increased crop stress and lost opportunities for utilisation of water and increased growth after each rainfall.
Non-leguminous plants and trees need substantial amounts of nitrogen for growth, and N is often applied as DAP for forest plants. However applying DAP alone lacks sulphur. Radiata pine (Pinus radiata) has been shown to benefit from the application of superphosphate fertiliser in the establishment stage. Growth and production of wood was improved, and there was an increase of organic matter and litter by the end of the rotation (source: Department of Primary Industries, Victoria, Australia: Bruce Sonogan, The Use of Fertiliser in Farm Forestry). Response of Tasmanian blue gum (E. globulus) was also best with a combination of deep ripping, fertiliser at establishment and weed control.
During planting, in preparation for future applications of liquid fertiliser, two 25mm diameter PVC tubes, one of 500mm length and the other of 700mm length, with some horizontal slots cut in, can be buried vertically near each tree, with about 200mm of the tubes above the soil surface. Liquid fertiliser containing nitrogen, phosphorus and trace elements applied to root depth have been found to be more effective than surface application. This is probably due to avoiding loss of surface-applied nitrogen due to rain (heavy in the tropics) or avoiding loss as volatile ammonia. Applying liquid fertiliser to cooler depths increases interception by feeder roots and avoids fixation of nutrients, particularly phosphorus and trace elements on surface organic matter and clay. Tests over several years on fruit trees fed liquid fertiliser by this method have not shown up any agronomic problems. Growth and productivity was improved compared to controls, perhaps due also in part to better penetration of oxygen to roots. A mobile application tank for liquid fertiliser, an electric pump, and delivery hose with a shut-off valve would be needed for periodical application to spur growth of the trees.
Blended fertiliser is placed below the trees and separated from the roots with a layer of soil to prevent burn. For legume trees, a fertiliser blend (legume biomass blend) consisting of granulated single superphosphate, potassium sulphate chips, dolomite or magnesite, together with a small amount of sea salt to supply sodium, chloride and trace elements can be used. A suitable liquid fertiliser containing phosphate, sulphur and trace elements (minus N) is applied periodically when needed for legumes after planting by filling up the PVC tubes.
For non-legume trees such as Radiata pine or gum trees, a suitable blended mix for quick establishment (non-legume biomass blend) can be produced, composed of granulated DAP, granulated single superphosphate, potassium sulphate chips, magnesium sulphate, and a small amount of sea salt. Try different ratios of the ingredients to give the best results. A guide can be obtained by comparing nutrient levels of legumes versus non-legumes and calculation from grain analysis values (see: Nutrition Management: Legumes). Non-legumes usually need less of the minerals than legumes but substantial nitrogen and sulphur is needed for continuous growth. Apply suitable Western Fertiliser Technology’s liquid fertilisers (eg. Super Energy, Super Liquid NPK and Rich Green) for NPK and trace elements periodically, or apply liquid fertilisers foliar with aircraft for very large areas (see Products page for more information).
An important consideration in the use of fertilisers for growing biomass is to achieve an ideal balance of the nutrients according to the desired C/N ratio of the product. The C/N ratio of the feedstock is an important consideration during processing of biomass. Once the balance in nutrients is achieved, application rates are important. Increasing the application rates of fertiliser for developing countries in the tropics, where inadequate levels of fertiliser are often used, would greatly increase quantities of biomass at harvest. Crops for biomass should be chosen which are adapted to the best use of rain, eg. crops with deeper root systems for interception of water and nutrients recycling, and those that are adapted to the local ecological conditions of climate and soil.
How do you view increasing greenhouse CO2 levels in relation to agriculture and trade?
A report on global warming by the interdisciplinary panel of climate scientists of the United Nations (IPCC), on 2 February 2007, placed green house gas increases in the atmosphere as the very likely, unequivocal cause of global climate changes. They viewed currently high levels of CO2, (384.9 ppm in Feb. 2007), as a serious burden for the planet. Scientists also recognise that global warming and climate change are capable of setting in motion irreversible, self-sustaining environmental events culminating in intolerable heat waves, droughts, fires, famines, storms, floods and sea level rises around the globe. A second report by the IPCC on the impacts of warming on the globe is due in April. The problem of global warming is unprecedented in the history of our civilisation and will be a severe test of our will to survive. As we have learnt from ecology, given time, only the fittest survive.
Carbon dioxide in the atmosphere is being captured as a carbon resource to replace dwindling fossil fuel reserves as renewable biomass to ethanol. Additionally, increased management efforts for carbon sequestration in forests and pasture soils are occurring. Legume plants and carbon-fixing microbes can muster bountiful atmospheric nitrogen (78.0% by volume) to tie up misbehaving carbon dioxide (0.0385% by volume) as biomass. Improved financial efforts for trading in carbon reduction are needed.
Carbon dioxide in the atmosphere, calculated as carbon, is at 105 parts per million by volume (384.9×12/44). Each ppm equivalent of carbon dioxide has been calculated to equal 2.20 billion tonnes carbon in the atmosphere (source: Energy Balance: Chris Rhodes; Carbon in the sky). His calculations show that we are currently emitting approximately 3.3 ppm CO2 each year and that around 40% of this, 1.3 ppm, are captured by the biosphere. The net CO2 emission is now approximately 2.0 ppm each year.
To prevent the increasing possibility of runaway global heating, we should resolve to reverse, within the next two decades, current levels of CO2 to a safer level. Levels of GHG in 1990’s held reasonably steady at around 354 ppm. The difference of 30.9ppm CO2 from today’s level, equivalent to 8.4 ppm as carbon, shows that 67.9 billion tonnes carbon need to be sequestered as soil and plant carbon. Additionally, removal of approximately 26 ppm CO2 from emissions to 2020 gives a total of 57.2 billion tonnes of carbon, or 9.6 billion tonnes carbon per year to be removed globally by 2020. CO2 emission reductions through clean coal technology for power generation, biofuels for cars together with a move to other renewable energy sources (solar, wind, wave, tidal) and increases in nuclear power generation would assist this effort. If not left too late, modern agricultural technology should be able to shoulder the huge challenge of carbon sequestration in soils and plants.
So-called ‘net benefits’ arising from warming trends for some countries would only be short-term, as the whole globe would heat up over time. The problem is therefore global and needs a global effort. Rich countries, which can presently afford to make carbon dioxide reductions, should take the lead. In the absence of the unprecedented effort to remove excess CO2, levels at 2020 would be, at least, around 411 ppm. To start carbon-reversing efforts in 2020, in the midst of unruly droughts and shortages of water, plus higher emissions, could become economically and technologically difficult in a degraded environment. We could be in an onerous position of not being able to return to lower, safer levels of CO2. The exact ‘point of no return’ is as yet uncertain, and that is what makes early action compelling.
Some scientists are however not so optimistic at reducing CO2 levels quickly, and consider that at best we should aim to keep the level of CO2 in the atmosphere static at current levels. The net annual increase of CO2 is around 2 ppm, so to stabilise CO2, the equivalent of 4.4 billion tonnes carbon needs to be reduced through sequestration and emissions reduction each year. If we can exceed this level of removal each year, CO2 levels could be slowly reversed to safer levels provided that current levels are, even now, not too high for climate stability.
Spirited, vibrant share-markets for market-driven trading in carbon, renewable energies, and carbon sequestration projects, are needed. Increasing economic activity by trading in carbon and new technologies would also improve global adjustment to declining crude oil reserves.
Under an amendment to the United Nations Framework Convention on Climate Change (UNFCCC) in 1997, the Kyoto Protocol, countries that ratified the protocol engage in emissions trading in CO2. Developing countries including China and India, together emitting high levels of greenhouse gases, were exempt from meeting emission standards. If the market-driven concept of Kyoto can be “tweaked” to make it a fairer system, countries including America and Australia will probably participate. We can then start serious trading in carbon-reduction technologies and projects to lower CO2 to safer levels, enjoy cool micro and global climates, and anticipate a secure, forward-looking world for our children.
The Kyoto Protocol aims to reduce greenhouse gas emissions below 5% compared to 1990’s levels, now viewed by many participating countries in the European Union to be grossly inadequate to stabilise CO2 emissions and address climate change. The Kyoto Protocol is also seen by many to be too complex to administer and seen to lack transparency, with risks of failing. Among its perceived problems are:
Large administration costs.
Difficult to monitor actual emissions or reductions based on estimates, and difficult to implement or enforce compliance.
Difficult to get accurate measures of performance for the money spent, ie. actual amounts of CO2 reduced per dollar spent.
Money allocated for carbon reduction elsewhere could be spent on unrelated projects.
As the problem is global, the Protocol should also have been relevant for undeveloped countries.
As its name suggests, a protocol is a draft of terms signed by parties as basis of an agreement relying mainly on diplomatic etiquette and decorum for implementation, rather than strict compliance. Thus some countries can take advantage of the many loopholes in the wording of the protocol to claim exemption from pledges made; for example, possession of forested areas claimed to compensate for increased GHG emissions
The open share-market, in contrast to a protocol, is a proven economic instrument rewarding companies, which exemplify leadership, initiative, enterprise and discipline. It has its own formal government regulated checks and balances, allowing the public to monitor progress by raising and lowering company share-price based on profitability and performance. The price of carbon and emissions limits can be set by individual nations, and companies and utilities can then buy shares to offset their emissions. A section of the stock exchange dealing in carbon and renewable energy, instituted in each country along established rules would allow investors to take part in a resourceful, vigorous and profitable system geared towards reducing excessive global carbon dioxide.
A virtual global thermometric reading on how well the world is succeeding in slowing and reversing the upward rise of CO2 will be given by keeping a close watch on monthly data of CO2 levels at monitoring points on the globe provided generously by NOAA/ESRL/GMD DATA.
Is global warming true or false?
Scientists working on stopping global warming would be happy if they were proven wrong and global warming stops suddenly. Most scientists would breathe a sigh of relief; hop into their SUV (if they have one) and go for a long drive in the country with family to celebrate. Global warming science is solidly based on a known and studied physico-chemical effect – the absorption of infrared energy by carbon dioxide. As an example, if we heat some water to boiling in a saucepan long enough it soon disappears- it has absorbed the heat energy and has evaporated. We know what has happened, so there is no need to question this effect. Global warming on the other hand involves increasing CO2 levels and global climate changes because of it, making it a very complex problem needing quick action.
Action on global warming, by changing old energy technologies, will prepare the world for the time when crude oil runs out. This action can be justified, even if warming is caused by some other effect not yet discovered (this is very unlikely). Doing nothing now would be a dangerous route to take.
Carbon dioxide, the main gas molecule causing global warming (there are lesser amounts of other more potent greenhouse gases) has the property of absorbing infrared (IR) radiation; the heat radiated by a hot body, for example, from a hot plate after cooking. After being heated by the sun during the day, our earth loses some of its heat at night by radiating it as infrared radiation back into outer space. Carbon dioxide in the atmosphere waylays this radiation and absorbs it, preventing some heat to escape thereby increasing the warming. Think of your head as an atom of carbon, and your two fists as atoms of oxygen. The CO2 molecule, shaped O=C=O sustains rapid upwards scissoring, or sideways stretching motions by absorbing IR radiation. It can gather kinetic energy and collide more often with other molecules of CO2 and absorb more IR energy. So if we increase the concentration of CO2 molecules by burning fossil fuels, less heat escapes the earth. We can confirm this effect by measurement in a laboratory with a sealed test tube containing CO2, and one without CO2. The test tube containing a high enough amount of CO2 can prevent passage of IR radiation through the tube. Chemists and physicists routinely use this property of absorbing IR radiation to identify organic compounds containing carbon-oxygen bonds in their structures, using an IR spectrometer.
The amount of heat retained globally is then a function of the concentration of CO2 in the atmosphere. As the CO2 increases, the globe gets hotter – it is as simple as that. Scientists are not yet sure of the global warming pathway. Are we on a linear, logarithmic or sigmoid pathway of increasing temperature in relation to increasing CO2?
One sees on TV solutions to global warming; for example, stationary orbits of mirrors in space between the sun and earth to reflect some solar radiation away from earth, or spraying water droplets upwards from ships in oceans to form heat-reflecting clouds. These costly solutions will not help if the amount of CO2 remains the same or increases. The only permanent solution to global warming is to return quickly to past levels of CO2, which we know are safe because the climate was stable then. It is urgent that we make valiant efforts to return to these levels, before the energy hill behind us becomes too steep to climb. We cannot afford to risk higher levels of 500 to 600 ppm CO2 as some suggest because each ppm of CO2 is equivalent to 2.2 billion tonnes of carbon. If we reach 500 ppm and find we need to return to 350 ppm levels for climate stability, that is 330 billion tonnes (330,000,000,000 tonnes) of carbon we will need to remove from the atmosphere – a superhuman task perhaps.
A draft UN report by the IPCC “Mitigation of Climate Change” is due for release at Bangkok on May 4. According to the pre-release draft “The most stringent scenario costing 3% of GDP, would limit greenhouse gas to 445 – 535 ppm by 2030, inside a range likely to bring a 2 – 2.4 degree C (3.6 – 4.4 degree F) rise” Source: Planet Ark, 11 April, 2007; Environment News. Limiting greenhouse gas at the higher level of 535 ppm assumes that the biosphere can tolerate the estimated average temperature rise of 2.4 degree C. For how long can human beings tolerate and live under the changed conditions if the biosphere breaks down at these limits?
What would be the GDP costs to reverse CO2 levels to 1990 levels by 2020 – 2030, and what does the world need to do to achieve this? If we cover most suitable land on the continents with forests by 2020 – 2030 with a crash program, what would be the estimated global GDP cost, and the estimated CO2 levels then in 2020 and 2030? If the answer is positive, is it possible for the world’s politicians to reach agreement for this action, and how soon?
At the moment CO2 in the atmosphere is around 384 ppm, and the globe is visibly changing physically and chemically. Polar melting continues, droughts are spreading, floods and storms are increasing, sea water is warming and acidity is increasing. Many scientists are now of the opinion that we have a window of only 10 to 15 years to act to save the planet. Let us hope there is much more time. We cannot let CO2 beat us. Big nitrogen at 78.0% by volume and the vast family of legumes will help turn the tide by growing biomass cheaply. Carbon can be sequestered under forest soils, and dry wood burnt with maximum efficiency can partly replace fossil fuels as a carbon-neutral heat source. Crude oil can then be saved for producing fertilisers and chemicals. Renewable energy sources such as solar and wind, together with atomic energy must come to the rescue quickly. It will take a long time to convert engine technologies of the millions (billions?) of cars, motorbikes, boats, planes and ships, and to run them on carbon-neutral biofuels.
Carbon trading could start soon in all countries. Those who do not participate in the vigorous international carbon and new technologies markets could be economically disadvantaged. Resource-rich, cash-poor nations with low sovereign risk should benefit the most.
On the recent good news front, scientists have shown that forest trees provided with improved nutrition increased growth by 21 percent compared to nil controls. When CO2 levels were increased from ambient by blowing CO2 around the trees, plus balanced fertiliser added, growth was increased by 47 percent over controls (Source: University of Michigan and US Dept. of Energy; US Forest Service; Science Daily- Anne Arbor; Soil fertility limits forests’ capacity to absorb excess CO2.). “The debate over how much CO2 trees will absorb should consider the limitations of soil fertility or other key resources in low supply” – Source. Key nutrient resources often in low supply for forest trees, compared to applied NPK, are soil amendments containing calcium and magnesium (eg. dolomite), sulphur (gypsum) and trace elements such as zinc, iron, manganese, copper, boron, molybdenum, cobalt, etc., together with sodium, chloride, iodine, selenium etc. from sea salt.
What do you consider to be the most pressing nutritional problems?
A pressing nutritional problem involves the increasing needs for the trace and ultratrace elements for crops grown in micronutrient-poor soils, and from nutrient leaching and depletion due to frequent N fertiliser use. Increasing soil acidity (low pH) and soil degradation are accompanying urgent problems needing close attention from leading fertiliser companies and nutritionists.
Chronic malnutrition in humans and animals in both developing and developed nations is a complex worldwide problem (source: R D Graham et al; Addressing micronutrient malnutrition; International Food Policy Research Institute, Washington DC, U.S.A.). As humans and animals obtain nutrients primarily from plants in organic forms, the route to amelioration of deficiencies lies in examining the two problems from the perspective of plants, soils and fertilisers.
Earlier on we discussed the importance of the trace and ultratrace elements in fertilisers. An enormous amount of research work has been done in the USA and internationally on the role of ultratrace elements in human and animal nutrition. Since the first meeting in 1986 of the International Society of Trace Element Research in Humans (ISTERH), an increasing number of reports have appeared which describe findings that suggest several of the ultratrace elements are more important in human nutrition than currently acknowledged (source: F H Nielsen, USDA, Grand Forks Human Nutrition Research Center, Grand Forks, ND 58202).
The term ultratrace elements, often used to indicate elements with established, estimated or suspected requirement generally indicated by microgram per day, could be applied to at least 20 elements (F H Nielsen, USDA). The amount found in a healthful diet, probably should be a value provided for an appropriate intake of the trace and ultratrace elements (source: F H Nielsen et al; USDA). Grain analysis of quality staple crops is a powerful and useful indicator of soil supply and the levels of trace and ultratrace elements needed in fertilisers for healthy, productive growth of plants.
Assigning a particular, essential role for micronutrients such as zinc, iron, copper, molybdenum or selenium has been a long and tedious process because of their highly complex functions and interactions. For plants, complications in the field (eg. damage from herbicides or leaf-disease) make pinpointing visual symptoms from particular deficiencies for treatment difficult. Some of the ultratrace elements may, like sodium (see Subbarao et al, Critical Reviews in Plant Sciences, 2003, vol 22 p391) be eventually classified as “functional nutrients”, defined as those elements which promote maximal biomass yield and/or which reduce the requirement (critical level) of an essential element.
From grain analysis of wheat, it is seen that ultratrace elements uptake levels are usually 1/10 to 1/1000 of the major trace elements such as zinc, iron and manganese (see Technical Questions and Nutrition Management this website). For example, uptake levels per hectare in 4 tons of wheat grain were approximately 22 grams, 16 grams, 2.6 grams, 0.24 gram, 0.12 gram, for boron, copper, molybdenum, cobalt and iodine respectively, with lower uptake levels of 0.06 gram and 0.05 gram for elements such as vanadium and selenium respectively.
Selenium content of grain is often used as a quality parameter; spinach and mushrooms usually contain higher levels of selenium. The very small amounts of the ultratrace elements needed per hectare to grow a large quantity of wheat indicates very low nutrient costs per hectare, ranging from approximately 0.7 to 5 cents per hectare. The benefit to cost ratios for the micronutrients are therefore very large compared to the NPK nutrients (see Technical Questions).
As discussed earlier for iodine, the minute trace and ultratrace elements exert their physiological influences as atoms activating a vast array of enzymes. The interactions between trace elements and ultratrace elements have been found to be nutritionally important (F H Nielsen et al). International studies have shown their critical importance in enzyme functions involved in growth and reproduction, glucose metabolism, digestion in animals and development of learning abilities etc. Trace and ultratrace elements interact closely in growth and reproduction in plants, microbial activity and nitrogen fixation, as well as their involvement in enzyme-mediated immune functions against disease-causing organisms and resistance against environmental stress such as heat, drought and frosts.
The ultratrace elements are set to assume great importance in the key areas of human, animal and plant nutrition. Plant nutrition is now a critical area for utilising forests and crops for CO2 removal from the atmosphere through photosynthesis, and for producing renewable energy as biomass in response to global warming and deteriorating climates. There is an urgent need to improve the nutrient status of seeds for germination and seedling vigour, resistance to pathogens, increased root growth to access water at lower depths for drought tolerance and access to nutrients for increased yields. Crops grown in nutrient- deficient soils produce nutrient-deficient seeds, further reducing yields when the seeds are used again for the next crop. Quality fertilisers containing the micronutrients will improve photosynthesis, water-use efficiency and yields, resulting in less waste of resources needed to produce the fertilisers.
Composting of crop residues and litter in the field by bacteria and fungal mycorrhizae is now a highly important area in the global carbon cycle to prevent CO2 increases in the atmosphere. The desirable microbial actions are sensitive not only to the availability of water, but also to the availability of trace and ultratrace elements, sodium and calcium in litter from fertiliser sources (residual N and P and other nutrients in litter are usually sufficient as substrates for microbes). Improvements in metabolism of microbes and respiratory activity, without excessive evolution of carbon dioxide from undesirable decarboxylation reactions are needed. Sea salt is a useful source of sodium, chloride, magnesium and trace elements.
Trace and ultratrace elements present unique management problems in addressing important nutritional needs of humans, animals and plants:
How do acidic and degraded soils contribute to nutritional problems?
Acid and degraded soils contribute to increased nutritional problems in humans, animals and plants; and are partly responsible for decreased soil organic matter and humus. Their percentage involvement in the total CO2 flux in the global carbon cycle is not known, but could be considerable.
Regular measurements of atmospheric CO2, commenced in 1958 at Mauna Loa Observatory, Hawaii, was at 314.4 ppm and has today increased to an average of 384.6 ppm; an increase of 70.2 ppm (source: Scripps CO2 Program, University of California, La Jolla, California, U.S.A). As each ppm of CO2 is approximately equivalent to 2.2 billion tonnes of carbon in the atmosphere, an increase of 154.4 billion tonnes of atmospheric carbon in 49 years (or 566.2 billion tonnes as CO2) has occurred. Noticeably In the past decade, there have been marked deteriorations in global climates and scientists have attributed this to substantially increased emissions of CO2. Extensive deforestation has also occurred globally since the earliest expansion of agricultural crops, and is still today contributing to large CO2 emissions. With many economic and safety problems inherent in carbon capture, transport and storage causing delay in implementation, a simplified technological approach to emissions mitigation is needed. A rapid global political response at the UN conference on Climate Change held next week at Bali, Indonesia is needed. Global reforestation, ending deforestation and stepped-up renewable energies are urgent solutions to the crisis.
Crop scientists have noticed that there has been a global trend of considerable falls of organic carbon in cultivated agricultural soils compared to earlier times. A significant level of this missing carbon could be responsible for adding to elevated CO2 levels in the atmosphere. In response to this, increased efforts on the part of agricultural scientists to improve the carbon content of soils by methods such as minimum tillage and improved pasture growth has occurred but has not fully achieved the desired results. Global economic pressures from increasing populations in developing countries and demand for food and grain has resulted in almost continuous cropping of the land and less attention given to improve the soil resource. Less time for pastures and soil conservation has added to the decline of organic carbon and humus needed for cementing soil particles into desirable crumb structures, which assists water and oxygen penetration to depth. Insufficient use of lime (best used as dolomite, or calcite plus magnesite) and substantial N-fertiliser use has resulted in increased leaching of nutrients and sharp declines in soil pH, together with degraded soils, reduced buffering capacities and fertility.
Additions of acid to soils as acid rain from SO2 sources have been a serious problem since early industrial development. Although SO2 emissions from power generation have been reduced to acceptable levels, emissions from the transport sectors remain. Impacts of acid rain on forest and crop soils are known, are well researched and efforts to counter acidity in forests have been made; however the soil resource continues its downward trend showing that the acid problem is highly complex. Acidity and degradation with lower soil carbon reduces the water holding capacity of soils, amplifying droughts which further increases oxidation and loss of soil carbon.
Acid soil conditions result in chemical changes reducing uptake of most nutrients by plants. Increased use of high analysis NPK fertilisers has come at a significant cost of secondary and trace elements. Liebig’s law of the minimum stating that the yield of any crop is always dependent upon that nutrient present in minimum quantity makes it imperative in plant nutrition, including human nutrition that deficiencies of all nutrients are prevented.
Not so obvious though has been the effect of deficiencies of the micronutrients and secondary nutrients sodium, calcium and magnesium on the activity of earthworms and soil microbes. Fungi and bacteria are responsible for organic matter sequestration in soils and conversions of many nutrients into useful forms such as vitamin B12. Micronutrient elements are critically important in metabolic processes and balanced respiration of soil organisms. Green crops obtain most of their carbon and oxygen from the atmosphere, but in the case of fungi (and most bacteria) there is extensive use of organic carbon as an energy source. Reduced levels of carbon sequestration in soils could indicate an energy and nutrient imbalance affecting conservation of soil organic matter.
Historically, organic-produce farmers were the first to notice that animal manures and crop residues in the field were slow at decomposing and returning to the soil as humus; indicating reduced activity of soil microbes and earthworms. To counter reduced composting and humus formation, they introduced the biodynamic method of increasing the quality and activity of microbes by packing cow horns with cow manure and burying them in layers under the soil for some time before use. The composted organic product, with a crumbly structure and a sweet aroma, is dissolved in water and spread evenly on the fields as a liquid fertiliser. In summary,
The dynamics of carbon accumulation in plants and soils is a highly complex subject and is intensely being studied by scientists to increase CO2 sequestration in soils. More complex and critical, from the perspective of global warming, is the continuing loss of carbon from agricultural soils. Soil-acidity and degradation has increased severely reducing agricultural productivity of farmers. Improved soil and organic waste management systems are needed.
Over 85% of farmers globally have very small farms and would benefit from careful use of active liquid lime to counter soil acidity (see Technical Questions, this website). A mixture in water of dissolved magnesium sulphate and a small amount of sea salt, plus some hydrated lime used in bricklaying would help reduce soil acids enabling higher K and P uptake by plants and increasing biological activity and earthworms. Cation-exchange capacities of soils will increase slowly, and fertility with improved soil structure will return; together with enhanced N-fixation in legumes, better responses to NPK-micronutrient fertilisers and increased soil organic carbon. For small-scale use of liquid lime in developing countries, only basic implements are needed.