Getting Good Results from Soil Management
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convince farmers to use this or that fertiliser, and of course it all
costs money. So what do you do? If you must spend money, how can you
be sure of getting a good result?
If you could see inside your soil, you would find a vast and complex
ecosystem, every bit as diverse as any coral reef or rainforest, but
of course sadly lacking in National Geographic film makers. Seeing
this diversity and complexity, you would probably find the first
question to cross your mind would be something like "How can a few
handfuls of fertiliser be enough to keep all this healthy and
productive?"
Just like a reef or forest, soil is a Living System that has the same
basic requirements and is managed in more or less the same way. There
is no need for salesmen or self-made experts; your soil can give you
all the information you need.
The most important requirement for any Living System is the physical
environment that supports it. In a rainforest, we would talk about
climate and geology, but in soil it is structure and friability. A
soil in which productivity is limited by physical constraints will
show certain symptoms to get your attention. It may be soft and sloppy
when wet, waterlog quickly and drain poorly; alternatively it may
compact easily and set like concrete when dry. You might also see it
seal itself off with a surface crust or form deep cracks that tear the
roots of plants.
The traditional view was that the relative proportions of sand, silt
and clay making up the soil caused all these things, and so they were
beyond anyone's ability to change.
Fortunately, research done on Australian soils has shown that a
different set of proportions is actually at work. It has been clear
for at least the last 40 years, from research done by Ted Mikhail,
that a combination of five elements - Calcium, Magnesium, Sodium,
Potassium and Hydrogen - work together to determine the functioning
and friability of soil. We call this the "Cation Balance" of the soil
and it forms the first and most important part of the Mikhail Soil
Balance System.
Unlike other soil balance systems, the Mikhail System avoids referring
to these elements as 'nutrients' as this has been a significant source
of confusion with older systems. Yes, they are essential plant
nutrients - as well - but that is not what we are talking about here.
The first component of the Mikhail System is in changing the
proportions of these elements in order to improve the physical
environment within the soil. This will require the use of materials
such as Lime, Dolomite and Gypsum, with benefits that will carry over
for many years. For this reason, the cost of such materials a Capital
expense to be amortised over five to ten years, but if we insist on
calling them nutrients, then our thinking will be geared toward
fertiliser, which is a production cost to be justified within the
course of a single season.
Try thinking of soil as being like a Diesel Engine: You may have to do
a bit of cranking to get it going, but once it starts your effort is
rewarded by easy and reliable running that continues indefinitely -
with only a small amount of checking and tweaking now and then.
Getting the cation balance right may take a bit of effort and expense,
but the benefits will continue for decades with only some occasional
tweaking.
The benefits of optimising the soil cation balance are substantial.
With good structure and friability, the soil will be more tolerant of
cultivation; it will retain moisture, but drain more easily and remain
well aerated; it will provide better access to roots and availability
of the nutrients they need. In short, this one action will make all
other aspects of farm management so much easier and continue doing so
for years.
The physical environment is also a bit like an apartment building, in
that when functioning properly, it provides many places to house
living things. After all, soil could hardly be called a Living System
if it was just an inanimate medium that kept plants standing up on
windy days and into which we poured nutrients like petrol into the
fuel tank of a car. Nevertheless, soil biology has always been the
hardest aspect of soil function to adequately deal with.
This is especially true if you wish to integrate biology into a 'whole-
system' approach like the Mikhail System, but again, it has been
research on Australian soils that has provided a way forward.
Not only do you need to know which groups of organisms to test for and
what levels are high, low or moderate, but such levels need to be
defined relative to other conditions in the soil. In other words, you
would not expect a sandy soil to have the same ideal population levels
as clay soil.
Like the plants we grow, micro-organisms in the soil require nutrients
- and the same nutrients as plants - but they do not complete with
plants to get them. Improved biological activity in the soil will not
increase the amount of fertiliser you need, in fact it will often
reduce it. The reason is that nutrients in the soil cycle between a
number of different forms such as 'soluble', 'exchangeable' and
'mineral'. Microbes help to facilitate this cycling, passing them on
to plants so that the same nutrients support the entire living
component of the system.
The thing that is usually most harmful to this process is any form of
'disturbance'. This means any shock or stress that can disturb the
normal activity of living organisms. A disturbance could be a sudden
change in temperature or moisture; it could even be a sudden 'flood'
of one or two nutrients from a heavy application of fertiliser. To
better manage the system and minimise the disturbance created, we
utilise the second Mikhail System component of "balanced plant
nutrition".
To do this, we must start by finding out what nutrients are presently
available in the soil and compare these to the needs of the plants we
want to grow. Clearly we will need to make up any that fall short of
this requirement, but if the physical environment is functioning
properly, there should be no need to use any more than this. Of
course, there may be some nutrients that are required in large
amounts, but we can further reduce the potential for disturbance by
splitting these up between two or three applications that are timed to
coincide with stages in the production cycle that require them.
But what about the organisms themselves? Should we brew up potions or
add special cultures? Should we dose the soil with tonics or special
'foods' to help them grow?
Over the years, it has repeatedly been shown that introducing
organisms to an ecosystem is not a wise thing to do. If the Australian
environment failed to benefit from the introduction rabbits, foxes,
cane toads, blackberries, dogs, cats, mice, rats and so on, what are
the chances that adding a new organism to the soil will have a better
outcome? It is probably just as well that many soil biology research
projects have shown that attempts to repeat this mistake of history in
soil have all been complete failures.
One of the most important discoveries to come from the research that
finally permitted incorporation of soil biology into the Mikhail
System was that although disturbed soils may fail to function
properly, they are not dead. We have not lost the organisms we need -
they are simply dormant. In fact, there are many people around the
World who look to the undeveloped soils of Australia as a good source
of new microbial species for various industrial or pharmaceutical
purposes. Everything we need is in the soil; we just need to make
better use of it!
To this end, research at SWEP laboratories has shown that small
applications of various 'bio-active' materials can do a lot to
stimulate the appropriate activity. The trick is to work out which
ones to use.
The new Complete Soil Balance Analysis from SWEP solves this problem
by providing information on cation balancing, balanced plant nutrition
and soil biology (according to the Mikhail System), all in the one
report.
The Mikhail System also provides a reliable strategy for applying the
recommendations from this soil test:
1. Cations first
Appropriate applications of materials such as Lime, Dolomite and
Gypsum to correct any imbalance, along with the time and moisture
needed for the changes to proceed.
2. Nutrients later
For properly balanced plant nutrition starting about six months after
correcting the cation balance.
3. Biology after every application
To help get the best results from each of the first two steps, using
the appropriate bio-active materials after each cation balance or
fertiliser application will speed up the whole process.
4. Monitor and Adjust
The effort and expense of getting your soil working right does not go
on an on. Repeating the soil test on a regular basis will let you keep
things working properly with only small 'top-up' applications, rather
than waiting for everything to go back the way it was and starting
again.