Foliar Fertilisers
- Foliar or soil application- which is better?
- How and why does foliar absorption work? Can I supply all the plant’s nutrient needs through the leaf?
- How do microbes fit in with foliar absorption?
Starter Liquid Fertiliser
Liquid Lime
- Why is liquid lime quicker to act than limestone or lime-sand?
- Will liquid lime increase the pH of my acid soil?
Grain Analysis
- Grain analysis, soil analysis, or leaf analysis, which is preferable?
- I usually apply 100 kilograms of urea and 150 kilograms of single superphosphate per hectare before sowing wheat. What is the equivalent amount of nitrogen in Rich Green Liquid N-S fertiliser?
- I would like to harvest around 4 tons per hectare of wheat grain. How much fertiliser do I need to apply?
- Grain analysis of my wheat is showing deficiency in some trace elements. For a 4-ton crop of wheat grain per hectare, what is the minimum amount of Soil & Foliar liquid fertiliser I need to alleviate the deficiency?
- Can I replace soil applied granular fertilisers with liquid fertilisers?
- In addition to fertilisers applied to achieve a certain yield, what other factors should I consider?
- I own a wheat and sheep farm of 6500 hectares in the wheat-belt. Each year I crop around 4000 hectares to wheat, barley, canola and lupins. I treat my crops and pastures with nitrogen and superphosphate, plus I have used the trace elements copper, zinc and molybdenum. I also test my soils each year. However I notice that my crops and pastures are not growing as well as in the past. Yields are down considerably, and I had problems this year from leaf disease and frost. The percentage of small grain at harvest has also increased. Do I need other nutrients such as magnesium, manganese and boron in my fertiliser program?
- Collecting a grain sample at harvest for analysis is easy, but is it as good as a soil sample for improving yields and quality? Is analysis of grain more difficult than soil analysis?
- My cereal and canola crop yields have been severely affected by frost for the past three years. How can I prevent frost damage?
Liquid and foliar fertilisers are much more economical than granular fertilisers as they utilise a high efficiency ratio of approximately 7:1 compared to soil applied fertilisers (Source: Michigan State University). This is due to balanced formulation and chelation, precise timing, even coverage and more efficient uptake.
Nutrients, especially phosphate, potassium and trace elements dispersed in the soil can become fixed through interactions, and unavailable to plants. By applying nutrients directly to leaves, the plant is able to manufacture sugar, starch, proteins and other complex foods and transport them to the roots where they are needed. Around the fine root hairs, microbes are fed this food, and in return they are able to mineralise soil phosphate, potash and other nutrients for the plant, in a symbiotic relationship.
The best time to foliar feed products is early morning when the plant's stomata are open. Avoid spraying if rain is imminent, or at high temperatures (above 26 degrees C). The amount of water used is important for good results. Plant uptake is improved with greater dilution of liquid fertiliser with water and applied as fine droplets. Avoid excessive misting as drift is increased.
Timing of application is important. Application before flowering prevents deficiencies and flowers from being aborted, increasing yield. Leaves are receptive to nutrients early in the growth cycle, and early-applied nutrients stimulate root growth in cereal crops before the onset of winter cold.
Dripper irrigation to feeder roots with Western Fertiliser Technology's products are as effective as foliar application, since the nutrients are in a chelated, available form, and are directly applied to the feeder roots with water. Fixation in the soil, especially phosphate, potash and trace elements is avoided as the nutrients are in a higher concentration, are not widely dispersed in the soil, and contains soluble nitrogen for rapid uptake by the roots.
Nutrients are needed in the leaf for the process of photosynthesis. In the long journey from the root surface to the leaf, some of the less mobile nutrients are less likely to reach the leaf surface in sufficient amounts. Direct foliar application of a balanced combination of major and trace nutrient elements, as a fine spray to the surface of the leaf, leads to an enormous increase in the efficiency of photosynthesis (like the fine coating on the surface of a solar heat collector increases its heat absorption). Improved photosynthesis means increased quality and productivity through the formation of quality sugars, carbohydrates and proteins.
It is not possible to supply all of the plant’s nutrient needs through foliar application only. A four-ton per hectare crop of wheat grain, for example, removes approximately 82 kilograms of nitrogen in the grain equivalent to 176 kilograms of urea. This large amount of nitrogen (and other major elements) is best applied through both root absorption (fertigation) and foliar absorption.
It is possible to supply all of the plant’s trace element needs through the foliar process. However, because plants need trace elements too in the early stages of growth, during and soon after germination and establishment, the modern way is to supply some of the trace elements at seeding (in, or on-the-furrow injection with liquid fertilisers) and some later through the leaf. Grain analysis shows that for trace elements such as manganese (for photosynthesis), molybdenum (for chlorophyll and nitrogen metabolism) and cobalt (for vitamin B12), approximately 240 grams, 2.6 grams and 0.24 grams are removed respectively by 4 tons of grain per hectare. Applying trace elements directly through the leaf increases fertiliser-use efficiency and yields several-fold. Remember in planning fertiliser programs, all nutrients are linked, and a chain is only as strong as its weakest link. Grain analysis of cereals, or analysing small fruit for fruit trees, can identify the weakest link.
The advantages of encouraging the growth and symbiosis of beneficial microbial colonies on the leaf surface could be more rapid conversion and absorption of nutrients into more useful forms of nutrients easily assimilated by plants; for example, the conversion of cobalt into vitamin B12 (cobalamin) by microbes. By encouraging the growth of friendly microbes on the phyllosphere, we can antagonise the growth of airborne pathogens thereby protecting the plant ; source: Michigan State University, USA . Common, friendly microbes hold the key to increased agricultural productivity. We can look forward to a rapid expansion in our knowledge of plant surface microbiology.
Furrow injection of liquid starter fertilisers containing NPK and micronutrients achieves all the objectives of starter on-the seed fertilisers, as well as much higher application rates for cereal crops. The liquids can be banded a few centimetres next to the seed in the soil, or surface-banded along the furrow in front of the press wheels. High rates of up to 100 litres per hectare can be safely applied. The latter method is the most popular because of its simplicity. Deep banding of NPK and trace elements below the seed is however more efficient, as trace elements such as copper becomes more available to plants when they are exposed to the action of organic matter and soil microbes.
An economical amount of hydrated lime (10 to 20 kilograms per hectare) in water can be injected along the furrow at sowing to protect the seed during germination from soil acids. An agitation tank to carry the liquid lime, a stainless steel electric pump, and an injector manifold and tubing are needed. Liquid lime used this way is economical compared to broadcast limestone, where up to a ton per hectare is usually applied. However, because only a small amount of hydrated lime is applied this way, yearly applications are needed. The change in soil pH should be monitored each year, and more used if needed. Large applications of the highly alkaline hydrated lime should be avoided, as it can cause some nutrient elements to become temporarily unavailable. Western Fertiliser Technology's BLEND-Tech system is available for the production of liquid lime.
It is worth noting that soil pH is recorded on a logarithmic scale, and so if the soil pH has fallen three pH units from the original soil pH (example from pH 7.5 to pH 4.5), the soil has become a thousand times more acid (10 x 10 x 10). It can be seen from this relationship that by increasing the pH of soil by just one unit (from any pH), 90% of soil acids can be removed. In the above example, the pH is changed from a thousand times more acid to a hundred times more acid than the original soil. This is why a small amount of liquid lime at pH 13 works so well in rapidly removing soil acids around the germinating seed, improving the growth of beneficial soil microbes, and improving nutrient availability to plants.
The best system would be to combine liquid lime applications (instant results) with approximately 500 kg/hectare broadcast limestone or lime-sand for longer term amelioration of acids.
Grain analysis, introduced in Western Australia by Western Fertiliser Technology, with data sourced from the Chemistry Centre of WA, overcomes these problems. A large number of grain samples from a wide area, over a long period of time (example, wheat, barley, canola and lupin) are used to obtain a range of analytical values for the major elements and the trace elements. The analytical ranges of the grains (low, medium and high) reflect soils with varied fertility and fertiliser treatments. A grain sample actually represents nutrient availability from a much larger soil mass (hundreds of tons) than a soil sample, as the plant has grown in a large volume of soil integrated over several months.
If a particular wheat grain falls in the low range, for example magnesium (0.080% - 0.123%), the farmer would benefit by using a magnesium fertiliser for the next crop. If the analysis falls in the medium range (0.123% - 0.146%) or high range (0.146% - 0.175%), magnesium fertiliser might not be used. The same type of analysis is performed for the major nutrients and trace elements, for each type of crop.
The amount of a particular nutrient removed in the grain can be easily calculated by multiplying the nutrient concentration in grain by the yield in tons per hectare. For example, if the grain contains 1.80 % total nitrogen and 0.140 % magnesium, and the grain yield is 3 tons/hectare, 54 kilograms per hectare of nitrogen (as N) and 4.2 kilograms per hectare of magnesium (as Mg) have been removed respectively in the grain. Nutrient uptake values are useful in evaluating the ability of a soil to supply a particular nutrient, which makes fertiliser advice more accurate.
Major benefits of grain analysis are a clean, dry sample taken at harvest, which can be posted easily in an envelope to the laboratory. The sample is analysed by the ICP spectrometer for nutrient status, together with quality parameters such as 100 grain weight, moisture, protein and starch. Interpretation of results and advice is simple and accurate if there is a sufficiently large data bank. There is also plenty of time available to plan and obtain fertilisers before sowing the next crop.
I usually apply 100 kilograms of urea and 150 kilograms of single superphosphate per hectare before sowing wheat. What is the equivalent amount of nitrogen in Rich Green Liquid N-S fertiliser?
The analysis values of granular fertilisers such as urea and superphosphate are usually shown as % w/w (per cent weight by weight). The analysis value of urea is usually 46.5% w/w nitrogen, so there is 46.5 kilograms of nitrogen in the 100 kilograms of urea you apply.
The analysis values of liquid nitrogen fertilisers such as Rich Green Liquid N-S are shown as % w/v (per cent weight by volume). The analysis value of Rich Green is 32% w/v nitrogen and 3.5% w/v sulphur. This means that 100 litres of Rich Green contains 32 kilograms of nitrogen and 3.5 kilograms of sulphur. To apply the equivalent amount of nitrogen (46.5 kg) in 100 kilograms of urea, you would then need to apply 100 x 46.5/32 = 145 litres of Rich Green costing approximately $0.30 per litre.
I would like to harvest around 4 tons per hectare of wheat grain. How much fertiliser do I need to apply?
If you work on the practice of replacing the nutrients removed, you would need
to calculate the amount of nutrients removed in 4 tons of wheat grain. This is
where the chart showing nutrient content of grains becomes very useful in
estimation. Analysis of grains can identify, for example, nutrient deficiencies
at depth for deep-rooted crops, eg. copper in canola compared to cereals. From
the upper medium concentration range of nutrients in wheat grain, 4 tons of
grain removes approximately (as elements):
|
82 kilograms 13.6 kilograms 24.0 kilograms 2.1 kilograms 5.8 kilograms 5.8 kilograms |
Nitrogen Phosphorus Potassium Calcium Magnesium Sulphur |
16 grams 248 grams 120 grams 124 grams |
Copper Manganese Zinc Iron |
22 grams 2.6 grams 0.24 grams |
Boron Molybdenum Cobalt |
On the basis that you usually apply 100 kilograms of urea and 150 kilograms of
single superphosphate per hectare for wheat, your fertiliser program consists of
approximately:
46.5 kilograms Nitrogen
13.6 kilograms Phosphorus
15.8 kilograms Sulphur, and
30.0 kilograms Calcium
For your fertiliser program, additional nitrogen, potassium, magnesium and trace
elements should be added as fertiliser to achieve a higher yield. Although
superphosphate contains small amounts of trace elements, these are usually at
inadequate levels to replace the requirements of a 4-ton crop of wheat.
Grain analysis of my wheat is showing deficiency in some trace elements. For a 4-ton crop of wheat grain per hectare, what is the minimum amount of Soil & Foliar liquid fertiliser I need to alleviate the deficiency?
From the nutrients in grain data, you would need a minimum of:
1 litre of Soil & Foliar Copper to provide 20 grams of copper.
6 litres of Soil & Foliar Manganese to provide 240 grams of manganese.
4 litres of Soil & Foliar Zinc to provide 120 grams of zinc.
3 litres of Soil & Foliar Iron to provide 120 grams of iron.
1 litre of Soil & Foliar Boron to provide 30 grams of boron.
4 litres of Soil & Foliar Copper to provide 2.4 grams of molybdenum.
1 litre of Soil & Foliar Iron to provide 0.3 gram of cobalt.
If the deficiencies in the trace elements were identified through grain
analysis to be manganese and boron, you would need to apply 6 litres per
hectare of Soil & Foliar Manganese and 1 litre per hectare of Soil &
Foliar Boron.
Can I replace soil applied granular fertilisers with liquid
fertilisers?
As discussed earlier, due to several reasons, the uptake of nutrients by
crops from liquid fertilisers are much more efficient than uptake from
granular fertilisers. This allows less fertiliser to be used, resulting
in considerable savings. As the availability and efficiency of liquid
fertilisers improve, it is expected that liquid fertilisers will replace
granular fertilisers; although to what extent is not yet known.
Long-term trends of liquid fertiliser use in Australia can be expected
to follow those set in USA, Canada and Europe. A comparison of nutrient
forms used in granular and liquid fertilisers illustrates the
efficiencies of liquid fertilisers.
| Nutrient | Granular | Liquid |
| Nitrogen | Usually made from ammonia (more expensive to granulate) |
Usually as urea and nitrate (less expensive) |
| Phosphorus | Immobile in soil (more needed) |
Foliar and soil-applied types of P more
efficient (less needed) |
| Potassium | Less mobile in soil and prone to fixation in some soil types | Potassium applied direct to leaves is rapidly available for improving photosynthesis |
| Calcium | Immobile in soil (less available in acid soils) |
Ideal foliar route for availability in leaves, flowers and fruit |
| Magnesium | Less available in acid soils | Ideal foliar route for availability in leaves, flowers and fruit |
| Sulphur | Prone to leaching in soils | Timing of application improves availability and economy |
| Trace Elements | Sulphate forms often used (more needed) |
Chelation improves uptake several-fold (less needed) |
Calcium and magnesium, in addition to their nutrition-related requirements, are needed to control acidity in soils and improve soil structure. Their use in this regard as lime or dolomite has been discussed earlier.
In addition to fertilisers applied to achieve a certain yield, what other factors should I consider?
Apart from calculation of the amounts of nutrients needed to achieve a
particular yield, using grain analysis data, some of the other factors
you should take into account when growing your crop are:
• Soil pH
• Soil type
• Drainage conditions; example waterlogging and salinity
• Tillage and seed-bed preparation
• Absence or presence of soil-borne organisms
• Absence or presence of weeds
• Fertiliser history
• Quality of seed and variety
• Level of organic matter in soil; presence of beneficial microbes and
earth-worms
• Previous type of crop (eg. legumes for nitrogen)
• Expected rainfall
• Occurrence of frost.
Many of the problems that occur today in farming systems management and
crop quality can often be shown to be related to deficiencies of
nutrients; notably trace elements, magnesium and potassium. Management
of strongly growing crops with good immunity towards environmental
stress makes management a lot easier and rewarding.
I own a wheat and sheep farm of 6500 hectares in the wheat-belt. Each year I crop around 4000 hectares to wheat, barley, canola and lupins. I treat my crops and pastures with nitrogen and superphosphate, plus I have used the trace elements copper, zinc and molybdenum. I also test my soils each year. However I notice that my crops and pastures are not growing as well as in the past. Yields are down considerably, and I had problems this year from leaf disease and frost. The percentage of small grain at harvest has also increased. Do I need other nutrients such as magnesium, manganese and boron in my fertiliser program?
I recommend a grain test for your wheat, barley, canola and lupins after harvest this year to identify the deficient nutrients (see Publications section). I would also recommend 100-hectare yield trials next season using your usual fertiliser plus our Super Energy trace element liquid fertiliser. Use a liquid fertiliser with Super Energy that contains the major elements potassium and magnesium (see Blend-Tech system). Always include a control plot (your usual fertiliser only) for comparison.
The return to cost ratio (profitability) for your farm depends on fertiliser-use efficiency, which also translates to water-use efficiency. Fertiliser-use efficiency is increased greatly by avoiding deficiencies of nutrients. The gross return to nutrient cost ratio is a useful parameter in making fertiliser and management decisions, and can be calculated, as below, for a 4-ton per hectare crop of wheat and nutrients removed (see data above). The low ratio for nitrogen compared to other nutrients indicates a higher per-hectare cost of the nutrient compared to the other nutrients. With the rising cost of oil and industrially fixed nitrogen, farmers should consider improving the nitrogen-use efficiency of crops by using balanced fertilisers.
| Nutrient | Gross return / Nutrient cost |
| Nitrogen | 10 |
| Phosphorus | 30 |
| Potassium | 35 |
| Magnesium | 30 |
| Copper | 8245 |
| Manganese | 1420 |
| Zinc | 2580 |
| Iron | 2592 |
| Boron | 4300 |
| Molybdenum | 5343 |
| Cobalt | 30818 |
The above ratios have been calculated from nutrient uptake data for 4-tons of wheat and full cost of replacement of the nutrients removed. However, few farmers practice replacement of nutrients removed, as part of the nitrogen and other nutrients taken up by the crop come from soil sources (the soil bank). Too much reliance on the soil bank lowers yields (unsustainable) and can cause soil degradation.
For a given yield of wheat (or other crop), you can get a measure of the contribution from soil nitrogen by subtracting the kilograms of applied nitrogen from the total uptake of nitrogen. Insufficient nitrogen use is often a cause of low yields, although at times farmers use an excess of nitrogen, causing imbalance with other nutrients such as potassium, calcium, magnesium and trace elements. Nutrient imbalances are a leading cause of lowered yields and quality (small grain).
You can see from the above data that the ratio of return from trace elements are higher than major elements, as trace elements cost less per hectare. Deficiencies of potassium, magnesium and trace elements such as boron, manganese, iron and cobalt in fertilisers would cost you more as lost yield and quality than in savings if they were not used. If your soils are of the acid or alkaline type, have been farmed for many years; have never received these nutrients in fertilisers, and if yields are falling, it is most likely that there are deficiencies needing treatment.
Collecting a grain sample at harvest for analysis is easy, but is it as good as a soil sample for improving yields and quality? Is analysis of grain more difficult than soil analysis?
Grain analysis can help you to identify whether nutrient elements in the harvested grain are in the low range, medium range or high range for a particular crop. This ability to identify the nutrient elements that fall in the low range is the first crucial step in deciding which elements need to be boosted in fertilisers to increase productivity. If your 100-hectare trials show a considerable improvement in productivity, the deficiencies are confirmed. Grain test results to date have shown some crops to be deficient in up to six elements, alerting farmers to the reason for poor yields and quality.
Grain analysis enables the uptake of a particular nutrient by the crop to be calculated; by multiplying the actual concentration of the nutrient in the grain at harvest with the actual grain yield. From this data, grain analysis can be used to improve the efficiency of fertiliser used, or to help target a particular, higher yield desired for the next crop.
Knowing nutrient levels in soil before sowing a crop is useful, but cannot always be relied upon to predict performance by crops due to various soil conditions which affects plant availability (eg. soil pH, soil type, tillage method etc,). For example, in high alkaline type soils, a high soil phosphorus reading may not guarantee that the crop will receive sufficient phosphorus during its growth. Foliar or soil applied liquid fertilisers containing phosphorus may be needed. Alkaline soils can also tie up manganese, boron and iron, causing deficiency even though a soil test could indicate sufficiency. Acid soils can reduce the uptake of molybdenum. The direct foliar route with liquid fertilisers for these elements is then preferable.
The analysis of grain is no more difficult to accomplish than soil analysis. In many ways grain analysis is easier as the sample is highly homogeneous compared to a soil sample, easy to post, keeps well as it is dry, and nutrient concentrations are much higher than in soil, making analysis more accurate. However choosing a suitable laboratory for analysing grain and soil samples is very important for achieving an accurate interpretation of the results.
My cereal and canola crop yields have been severely affected by frost for the past three years. How can I prevent frost damage?
Throughout the world there are huge economic losses to frost damage reported each year. There are more economic losses to frost damage than any other natural hazard including drought, floods, hurricanes etc. Most countries with temperate climates experience frost damage to crops and even tropical countries can have frost damage at high elevations. When immature crops are damaged, grain yield, drying rate, and grain quality can all be affected; source: Extension Service, University of Minnesota, USA. Shoot tips, and tissue in basal parts of shoots and stems can be irreversibly damaged by frost, curtailing the supply of water and nutrients.
Whether or not frost damage occurs depends on many factors including the plant species, crop variety, cold-temperature hardening, cultural practices including pruning, fertility and irrigation, weather conditions and the presence of ice-nucleation active (INA) bacteria; source: University of California, Davis, USA. Although it would be difficult to completely prevent some frost damage to crops, frost damage can be minimised by applying balanced fertilisers and improving fertility management of problem soils (saline or acid). As you have suffered crop damage by frost for three years in a row, it is most likely that the cause could be severe nutrient deficiencies, in which case I would recommend grain analysis and soil analysis: see: Publications section.
During cold-temperature hardening, plants accumulate protective soluble carbohydrates (glucose, sucrose, raffinose) and proteins in the cell solution, which act as antifreeze solutes. Plants utilise this ability called supercooling to survive freezing temperatures below zero degrees C. Moderate supercooling prevents the formation of ice crystals within the plant tissues, which disrupts plasma membranes causing damage; source: Swedish University of Agricultural Sciences, Uppsala, Sweden.
The soluble carbohydrates and proteins utilised as cryo-protective solutes are synthesised by plants during carbon fixation from atmospheric carbon dioxide (greenhouse gas) for growth and reproduction (see photosynthesis, in earlier discussions). Photosynthesis efficiency by chlorophyll relies heavily on a balanced supply of all the major nutrient elements and trace elements taking part in enzyme-mediated metabolic processes. Some of the functions of the major nutrient elements, of particular importance during photosynthesis are nitrogen (for proteins and enzymes), phosphorus (photosynthesis and energy as ATP), magnesium (for chlorophyll formation), sulphur (for protein); and calcium and potassium to maintain cell wall rigidity and strength to resist frost damage.
The trace elements iron, zinc, manganese, copper, boron, molybdenum and cobalt are all closely involved in plant photosynthesis process and nitrogen metabolism for the synthesis of the carbohydrates and proteins. The ultra-trace element iodine, often used in fertilisers for iodine deficient pastures, is closely associated with chlorophyll function and starch synthesis; and is also important in human and animal nutrition. Utilising grain analysis, replacement of the iodine removed from soil by crops is low; for a 4-ton per hectare crop of wheat being approximately one-half that of cobalt at 0.12 gram per hectare. Farmers would be interested in comparing analysis of grain from frost-free crops and frost-damaged crops. Comparison could then be used in identifying the nutrient needs of frost-damaged crops for treatment.