THE SEVEN BIGGEST SOIL BLUNDERS
1 Don’t drive blind
FERTILISERS represent a major investment and, in this context, anything that improves nutrition efficiency will reduce costs.
The simple strategy here is to apply only what is needed, when it is needed and nothing more.
Monitoring is necessary to achieve this efficiency. Fertilising without soil tests is like electioneering without opinion polls.
The nature of mineral inter-relationships is such that the application of a mineral that is not actually required can cause more problems than undersupply of this nutrient.
The message here is ‘don’t drive blind’ - use a good soil test and supply exactly what is needed.
Soil tests and minimalist
magic
You may be involved in broadacre production, where there is such a limited fertiliser budget that you are not able to correct many deficiencies, but soil tests still have a critical role to play.
There appears to be considerable benefit in applying a small amount of nutrition, directly into the root zone, in accordance with nutrient requirements and maintaining the desirable balance.
I have seen good results where soil test requirements have been addressed, via liquid injection, at rates of just one per cent of what was recommended.
For example, if your soil needed one tonne of lime, 250kg of potassium sulfate, 20kg of zinc sulfate and 10kg of soluble boron, then your liquid injection might involve 10kg of micronised lime, 2.5kg of potassium sulfate, 200grams of zinc sulfate and 100 grams of solubor (soluble boron) per hectare.
These minerals should be combined in 30 litres of water per hectare but ideally that water should be substituted for a microbial inoculum.
Then you are effectively putting the microbes behind the minerals.
This minimalist, root zone balancing approach can prove a cost effective, and highly productive alternative.
This blend, for example, could be put together for less than AUD$30 per hectare.
Biological agriculture differs from conventional organics in that organics is often about a great list of what you are not allowed to do but there is very little emphasis upon what you should be doing to increase crop quality and yield. The biological approach, however, is all about things you can do to improve productivity and profitability. In this context I usually focus upon positive strategies and their rationale. This is the first in a series of three articles where I will look at negatives in the hope that this information may serve to help you avoid some of these mistakes. We will look at blunders in soil and crop management and we will also consider business blunders in your farming enterprise. There are obviously a whole suite of potential mistakes, but I have identified the most costly of these. Here are seven soil scenarios to avoid where possible.
- Graeme Sait
2 Miscalculating calcium
CALCIUM is the most important mineral in the soil and it is also the number one mineral for microbe, plant, animal and human health.
Balance is a core concept in mineral management but it is particularly critical in relation to calcium nutrition.
Each soil has a unique capacity to store a specific amount of calcium, based upon it’s clay component.
A light sandy soil may require a maximum of two tonnes of lime p/ha while a heavy soil may require two or three times that amount.
The miscalculation in relation to calcium may be linked to a misunderstanding of the role and application rates of this mineral.
There is also often a failure to factor in the role of synergists, like boron, to achieve optimum calcium performance.
Calcium - much more than a
ph modifier
At a dairy industry field day I attended I was stunned to see a bunch of soil scientists standing in a soil pit passionately debating the pros and cons of ph management with lime.
There was conflicting research data in relation to the benefits of lifting ph in acid soils and the farmers present were left scratching their heads when trying to decide what to believe.
I was surprised at the need for debate because the pasture was so obvi- ously calcium deficient and so were the livestock.
Calcium is a critically important nutrient and calcium nutrition is much more important for plant, animal and microbe health, and weed pressure, than for ph management.
If you correct calcium as a nutrient, and balance it with the other core cations (magnesium, potassium sodium, etc), then ph takes care of itself.
Calcium is called the ‘trucker of all minerals’ because it is intimately involved in the movement of nutrients in and out of the cell.
This applies to microbes as much as to plants and animals.
Calcium is also a key mineral determining cell strength as, in combination with silica, it is built into the cell wall.
Shelf-life, resistance to disease and reduced insect pressure are all benefits of increased cell strength.
In the paddock where the soil pit had been prepared and the scientists were locked in combat, I counted over 25 different species of broadleaf weeds.
These are indicator weeds that germinate where calcium is lacking.
This alone should have been enough to indicate the need for calcium but there were several other signposts.
The brix levels in the pasture were low and the indicator line, when looking through a refractometer, was sharply defined.
A refractometer offers a reliable guideline to calcium levels in the crop.
If the plant contains good levels of calcium, the indicator line is fuzzy and indistinct, but it sharpens and becomes more defined as calcium be- comes deficient. The sap ph was also low in this pasture and this also helped to confirm a calcium shortage.
It is obvious that if you are exporting calcium off the farm twice a day as milk (dairy farming), you do need to compensate for this removal.
A penetrometer revealed a tight, closed soil with a hardpan at 20cm, yet another indicator of a soil screaming out for the flocculating force of calcium.
3 Premature nitrogen (N)
reduction
IT is common to encounter growers, enthused by the potential of the biological approach, who decide to reduce their nitrogen inputs.
This can be a trap for young players in some soils and the subsequent yield reductions can serve to dampen the ardour of even the most passionate biological convert.
This problem of premature nitrogen reduction is most pronounced in high magnesium soils and this costly blunder can be avoided if you understand the mechanics of nitrogen utilisation in the soil.
There are three reasons why it may not be a good idea to reduce nitrogen inputs in high magnesium soils.
The first of these relates to the alkalising effect of high magnesium.
This mineral has 1.4 times more impact upon soil ph in comparison to calcium and high ph sponsors the instability of nitrogen.
There is increased outgassing of ammonia in these soils, so more nitrogen is required to achieve the desired response.
The second and third reasons are both linked to the role of microbiology in the whole nitrogen equation.
Many growers assume that most of their nitrogen requirements are addressed with applied N and this is not the case.
The majority of the nitrogen needed for high production horticulture comes from natural sources.
Electrical storms oxidise nitrogen gas in the atmosphere and, the nitrate nitrogen that results, charges raindrops with a bounty that greens all that it touches.
Nitrogen-fixing bacteria in the soil and on the leaf creatively combine
molybdenum and iron to manufacture nitrogenase, an enzyme that mines the massive reserve of atmospheric nitrogen (74 per cent) to fuel plant growth.
If we understand these natural processes, then we are more likely to create conditions conducive to their success.
Free-living nitrogen-fixing organisms, for example, are highly aerobic.
In fact, Azotobacter are the most aerobic creatures on the planet.
Tight, closed, high magnesium soils are those that struggle to breathe and their lack of oxygen spells a lack of free nitrogen delivered from the atmosphere.
Similarly, the potential for nitrogen recycling reduces in high magnesium soils and this signals a greater need for applied nitrogen.
Plant protein contains 16 per cent N and this is a recyclable reserve that is there for the taking (assuming you have the aerobic biology present to do the job).
The 2.5 tonnes of bacteria p/ha found in a good soil are also a bountiful supply of harvestable N.
Bacteria store 17 per cent nitrogen in their bodies and this can equate to over a tonne of urea p/ha if it can be successfully released.
This release process is the role of other creatures in the soil including beneficial nematodes.
These blind, microscopic worms have a carbon to nitrogen ratio of 100:1.
In the process of consuming 20 bacteria with C/N ratios if 5:1 (20 x 5 =100) to satisfy their carbon requirements, they spew out the 19 units of nitrogen not required.
In high magnesium soils, the lack of all important oxygen means less nitrogen-fixation, less recycling and more nitrogen from a bag.
If you can improve your calcium to magnesium ratio in these soils you will sponsor more oxygen delivery and thereby reduce your reliance upon applied nitrogen that is destined to constantly increase in price in line with rising oil prices (Peak Oil).
4 Mismanaging the Window
IT often seems that it is human nature to procrastinate in everything but matters of the heart. Even lovers would be best advised to adopt a little more watchful waiting in light of the 40 per cent failure rate that currently marks their leap into the unknown.
However, soil management is not well suited to fence-sitting. It is criti- cally important to allow enough time to benefit from soil correctives before planting your crop and all too often, the last minute rush compromises fertility performance.
It takes two to three weeks to receive the results from a soil test and then your mineral requirements must be sourced, delivered, applied, incorporated and mineralised before you put a plant in the ground.
Similarly, there must be enough time for the residues from the previous crop (or your green manure crop) to have broken down, or you risk the expense of more nitrogen than you may otherwise have required.
It all comes down to better management of the small window that comprises crop rotation, if you are to avoid this costly blunder.
Even if you are trying to delay the expense, it is poor economics to compromise your upcoming season to save a few dollars in interest.
Plan and budget to allow sufficient time to achieve the maximum bang for your buck from soil correctives.
5 Don’t spread and pray with
NPK
The mismanagement of these three minerals has created more problems than any other mineral trio including mercury, sulfur and uranium.
Nitrogen has been the most destructive of the three.
It is the major player in the loss of humus in our soils and it is also the chief source of the greenhouse gas, nitrous oxide which is 310 times more thickening than CO2.
Acid phosphate fertilisers are major players in the destruction of beneficial soil fungi including the Mychorrhizal fungi responsible for one third of the humus formation on the planet.
Potassium is often overused leading to inhibition of calcium and magnesium.
Calcium is involved in nutrient density and soil structure and excess potassium impacts upon both of these.
Here’s five ways to improve
NPK management
a) Don’t apply NPK unless it is
needed.
It is common to see potassium still applied in high potassium soils.
Not only is it the most expensive mineral but it is counterproductive to apply it when it is not needed as it will reduce uptake of calcium, phosphorous and boron.
Similarly, phosphorous oversupplied.
You may still need a little starter P in high phosphorous soils because the oversupply has sponsored a shutdown in the plant’s capacity to stimulate soil organisms to release phosphate as required.
However, the P requirements for the rest of the season can be easily supplied by stimulating biology to solubilise locked-up phosphorous.
If you have excess N according to tissue tests, why on earth would you
is
often
apply more. It is so common to see growers locked into maintenance doses that are not needed and are often the cause of costly imbalance.
b) Always stabilise NPK inputs.
Nitrogen can become a highly leachable nitrate that drains your bank account, pollutes our waterways and poisons our people, if it is not stabilised. Phosphate can tie up within days and become part of an estimated 10 billion dollars of ‘frozen phosphate’ locked within Australian agricultural soils. Potassium is also easily leached in low carbon soils, particularly following high rainfall, and this is an expensive loss.
The key to stabilising all three minerals is to combine them with humates.
Urea can be combined with humic acid in liquid form to create a stable urea humate and this is probably the best way to apply nitrogen.
Humic acid can also be applied with liquid potassium nitrate but it is not compatible with potassium sulfate.
Fulvic acid can be used to stabilise potassium sulfate but it is more expensive than humid acid.
The combination of nitrogen and potassium, with a mineral called zeolite, is another highly effective stabilising strategy.
This mineral serves as a storage system for these two minerals.
Zeolite features a honeycomb structure which offers a massive network of hiding places for soil foodweb creatures seeking sanctuary in that dog-eat-dog world. There are pore sizes present in this honeycomb that correspond exactly with the size of the potassium and ammonium ions.
These minerals slot into these pores like hands into a glove and are held there more effectively than when stored on the clay colloid.
c) Use biology to reduce NPK
inputs.
Although many growers assume that most of their nitrogen requirements come from a bag, this is not the case.
A large percentage of the nitrogen utilised in crop production is supplied by biology and if we acknowledge and understand this fact, then we can work to optimise this natural supply.
Similarly, the release and delivery of phosphate and potassium is a biological process.
If we introduce and/or nurture these creatures, it can seriously reduce NPK inputs. Nitrogen-fixing organisms can be introduced as inoculums.
The success or failure of these inoculums is often determined by the presence of molybdenum in the soil.
If you don’t have 0.5ppm of molybdenum in your soil, you may struggle to achieve significant nitrogen-fixation. Molybdenum is required for bacteria to build nitrogenase, the enzyme required to convert atmospheric nitrogen gas into ammonium nitrogen in the soil.
Another way you can reduce nitrogen inputs is by ensuring that you have a fully functioning nitrogen recycling system.
Protozoa play a big role here. Bacteria have a carbon to nitrogen ratio of 5:1 which means that their body contains almost 17 per cent nitrogen.
There can be two and a half tonnes of bacteria p/ha in a good soil and this equates to over a tonne of urea locked up in their bodies and not available to the plant. Protozoa eat 10,000 bacteria a day and recycle their nitrogen to make it plant-available.
Many soils lack protozoa but they can be inexpensively reintroduced using lucerne teas.
For some reason, all three forms of protozoa are found in large numbers on lucerne (assuming that they have not been killed off with pesticides used to kill lucerne flea).
They can be easily multiplied and introduced to restore nitrogen recycling and they have an added bonus of firing up your earthworm populations. Protozoa is a favourite food source for these dynamic fertiliser machines.
Phosphate solubilising organisms can be introduced with inoculums or their numbers can be boosted with simple additives like molasses or fulvic acid.
Another highly productive strategy involves stubble digestion programs.
Cellulose-digesting fungi release organic acids that can release locked up phosphorous in your soils.
Soil-life testing reveals the decimation of these creatures through tillage, fungicides, herbicides, nematocides, acidic phosphates and high salt fertilisers. It is a simple, inexpensive process to brew up these organisms and apply them to crop residues to speed the breakdown of organic matter. Not only do you build carbon (for which you will soon be paid carbon credits) but you have also improved your fungi to bacteria ratio and now have a soil full of fungi that solubilise phosphate, protect from disease and promote plant growth with their unique exudates.
There are also inoculums available that can solubilise potassium and they are particularly productive in clay soils where potassium can become trapped in the clay platelets.
In these soils the small potassium molecule can be set free by organisms that fancy potassium.
If you are brewing compost teas you can encourage these brews to become potassium generating by combining a little potassium sulfate as a food source during the brewing process.
This encourages the multiplication of potassium solubilising organisms that are present in all compost teas, as they now have a food source specific to them. The bottom line here is that we need to reduce our reliance on NPK inputs as they are destined to dramatically increase in price in line with peak oil and peak phosphate. The message for primary producers is to work more closely with a natural system to reduce your requirement for these increasingly expensive inputs.
d) Understand the NPK synergists.
No mineral works in a vacuum. Mineral interrelations influence fertiliser performance and if we understand these relationships we can reduce NPK inputs.
The father of soil science, Dr William Albrecht, paid the price for maximising NPK performance when, at the peak of his career, a consortium of fertiliser manufacturers successfully shut down his career.
It had become obvious that when farmers throughout the US began to adopt Albrecht’s soil balancing approach, their need for NPK reduced considerably and Albrecht became a liability to the fertiliser industry.
So what are the key minerals and ratios that affect the performance of nitrogen, phosphorus and potassium?
The most important ratio is the calcium to magnesium ratio. If there is too much magnesium in relation to calcium there will be an inhibitory effect upon nitrogen and potassium and you will need more of these minerals to create the same effect.
If you have overdone your nitrogen you will require more potassium.
If you over-apply lime you will also negatively impact potassium uptake.
If you apply too much zinc you can shut down some phosphorous and if you overdo potassium, phosphorous is also negatively impacted.
Finally, if you can balance potassium and magnesium in terms of ppm on your soil test (work toward equal numbers of ppm - i.e. 200 ppm of magnesium and 200 ppm of potassium) then you will achieve maximum uptake of both minerals and, interestingly, you will discover that you have significantly improved your uptake and utilisation of phosphate.
The reason for this relates to the fact that magnesium is a phosphate synergistic while excess potassium can be a phosphate antagonist. If you get these two minerals in balance you will see the best uptake of both magnesium and potassium and you will also see optimum uptake of phosphorous.
e) Timing, rates and application
methods.
It matters when and how you apply NPK and application rates can also have a big influence upon the performance of these minerals. Recent research with urea, for example, revealed a huge difference in response based upon rates of application.
In this study, looking at the effect of split applications, urea was applied in a single application of 100kg p/ha compared to two applications of 50kg p/ha contrasted with three applications of 33 kg per hectare and so on, right down to 10 applications of 10kg p/ha. It was determined that four applications of 25kg p/ha produced a 108 per cent yield increase over the single application of 100kg p/ha.
There are many times when we simply apply much more nutrition than a tiny, new plant requires. It is more cost effective to apply NPK in the root zone rather than broadcasting and, contrary to common practice, it is not a good idea to apply nitrogen months before you plant the crop.
6 Not adjusting to changing
climatic conditions
THERE are few farmers who now deny that a changing climate is impacting their operation.
In all of the 42 countries in which we at Nutri-tech Solutions (NTS) work,
we see conventional agriculture challenged with a multitude of problems associated with climate change.
In intensive horticulture, where precision programs have been painstakingly developed over decades, the rule books are being thrown out in the face of this change.
Soil temperatures are different, sunlight hours have changed, rain is falling where it never used to fall and drought is persisting beyond anything previously experienced.
In SE Qld, we have had a horror year for horticulture where macadamia growers have experienced unparalleled Phytopthora pressure, strawberry growers have prematurely ended their season in the face of paralysing grey mould pressure and ginger farmers are seeking new farms to escape the Pythium plague.
The problem here is that many of the fungicides seem to have become ineffective with this level of pressure?
Interestingly, the growers that have best survived the onslaught have been those utilising biological approaches.
This really is the shape of the future because it has become obvious that it is more productive to work with a constantly adapting natural system than working against it.
The chemical industry will simply not be able to develop new products fast enough to account for resistance that occurs through overuse during extreme pest pressure.
Although this will prove painful to many who are forced to adjust to this brave new world, the end result will be positive. There will finally be a widespread recognition that we need to address the root cause of these diseases rather than relying upon short-term chemical solutions and our farmers, our food and our planet will all be the benefactors.
One other painful change may involve an acceptance that the writing is on the wall and farming will only become more difficult in some areas. I personally believe that we have seen the trends for some years and the smart operators are now making the hard decisions and moving to areas less troubled.
This can be difficult for farmers who have inherited family farms. They are often wracked by guilt at the thought of selling land soaked with the blood sweat and tears of their parents and grandparents and they feel that they have failed. This is understandable but it is not real.
The best approach here is to imagine what you would feel if your own children were involved. Imagine one of your children farming with exceptional skill but failing year after year in the absence of moisture.
Would your prefer them to maintain the misery in the name of a piece of land or would you prefer them to move on and enjoy their short life in a more hospitable area?
7 Using counterproductive
inputs
SOMETIMES we can shoot ourselves in the foot while attempting to provide protection or nutrition and it is worthwhile understanding how to avoid this self inflicted pain.
If you have reached the point of recognising that your success is intimately linked to the health of your microbe workforce, then you will understand that you should reconsider the use of any input that compromises that workforce.
CSIRO scientist, Dr Margaret Roper, has determined that the Triazines are contributing to serious damage of soil life. In fact, she suggests that Simazine and Atrazine may cause permanent damage to your workforce. There are other options to these soil poisons and they should obviously be considered if you would like to tap into the multiple benefits of beneficial biology.
Perhaps you have wondered how and why potassium chloride was demonised while soft rock phosphate was canonised in the folklore of biological agriculture.
Here’s how it happened. The lateCharles Walters, founder of the influential bio-ag publication, Acres USA, was researching a book on weeds.
He decided to use a radionics scanner to investigate the influence of various fertilisers upon crops in contrast to their effect upon weeds.
In the process, he discovered that Muriate of Potash actually reduced the General Vitality (GV) of the crop while increasing the GV of weeds.
It is obviously not desirable to give weeds a head start but this is what this popular input appeared to create.
This research also led to the discovery that soft rock phosphate was an input that had the opposite effect. This soil food lifted the GV of the crop while seriously reducing the GV of the weeds. This was one of the reasons that these two inputs became seen as negative or positive influences in sustainable crop production.
Potassium chloride has the highest salt index of any fertiliser and this can be detrimental to soil life.
The late Bruce Tainio, a leading American consultant, claimed that potassium chloride is poorly absorbed through the leaves even though it is the basis of many foliar fertilisers.
Although chlorides are sometimes required from a nutrient perspective, it is much more likely that sulfur will be needed. Potassium sulfate is well absorbed as a foliar, particularly if combined with a soluble fulvic acid powder, so it is the preferable K source for those concerned with sustainability.
Acid phosphate fertilisers are a particularly poor investment as you will access just 27 per cent of your phosphate investment before the remaining 73 per cent becomes part of the massive frozen reserve of this mineral locked within Australian soils.
You can reduce this loss factor considerably by combining soluble humate granules with your DAP/MAP but, depending upon your crop, it is often a better idea to opt for soft rock phosphate or granular guano, where phosphate is released throughout the crop cycle.
Cereal crops, legumes and vegetables are really the only crops that justify the use of unstable, ‘fast food’ phosphate. Even here there is a better response if the acid fertilisers are combined with guano as the combination of soluble and slow release will always be more productive.
The last of the counterproductive inputs we will discuss is probably the worst. Nematicides are amongst the most dangerous of farm chemicals, killing more farm workers worldwide than any other ‘corrective’.
These chemicals are a perfect example of the double edged sword that lops off more than intended.
When we look beyond the extractive approach at a more holistic solution we discover that many of the chemical ‘solutions’ are anything but.
The natural control of root knot nematodes involves three creatures which are all impacted by nematicides.
Predatory nematodes, Mychorrhizal fungi and nematode trapping fungi are all affected by these chemicals and, ironically, the first creature to return to the fray is the root knot nematode and now he has no competition.
This is why nematicides breed more nematicides and are a classic case of the bankruptcy of this system!
In conclusion
An open mind is an essential prerequisite to survive and thrive in a world where the only thing certain is change.
One aspect of this flexibility is the capacity to learn from our mistakes.
Ill-informed nutrition, nitrogen mismanagement, misunderstanding of mineral inter-relationships, mistiming and miscalculating fertility inputs and a failure to adapt, are some of the key blunders that make farming less fun.
I trust that you are now better equipped to weave your way through these potholes as you strive to minimise pain and maximise pleasure in the planet’s most important profession.