A Vision For Sustainable Row Crop Farming
(Originally posted on Applied Mythology on 3 15/11)
It has been estimated that between increasing standards of
living and increasing population, there will be 1.5 to 2 times as
much demand for food as there is today by mid century. To
meet that demand without adding more farmed land, the current
farms must achieve greater productivity per acre or hectare.
The challenge is to do that without increased, and hopefully
decreased, environmental impact. As challenging as that
sounds, I actually believe that this is possible because of a
number of agricultural advances that have been made over the
past few decades. I'm not saying it is obvious that we will get
there, just that it is possible.
These Are Not My Ideas
As part of my consulting business, I have had the privilege to
spend time reading hundreds of scholarly articles about
agricultural sustainability. Over the past few decades there has
been an extensive research effort to quantify the environmental
problems/benefits of various farming practices. I have not
conducted any of this research myself, but I have had the chance
to digest it and learn from all the hard work that was involved.
Many of the studies were based on field research over many
years, often 10 or more. This academic research has also been
complimented by commercial innovation on the part of farm
equipment companies, agricultural chemical companies, seed
companies and other commercial entities. The most important
aspect of this innovation cycle is that progressive farmers have
tested, integrated, and perfected the new farming options that
flow from the academic/commercial activity.
What emerges from all of this effort is a vision of the kind of
agriculture that could not only feed the world, but do it in an age
of climate change and with far less impact on the environment
than has been the case in the past. Agriculture is a vast and
diverse industry, so I will limit my discussion here to the largest
segment: rain-fed row crops (wheat, soy, corn, cotton...). For
these crops the five, quantifiably best, farming practices are as
follows:
No-till Crop following Wheat
1. Minimum Tillage
When soils are plowed or otherwise disturbed, the organic
matter content declines and with it the complex aggregate
structures and biological systems of the soil. When soils are
farmed with "no-till" systems or related options, the soil organic
matter is preserved and soil "health" is enhanced. This practice
also leads to less fuel use, far less erosion, and thus less off-site
movement of fertilizers or pesticides. Minimum tillage systems
require specialized equipment. They are aided by good seed
treatments and genetics, by either herbicide tolerance traits or
selective herbicides. The transition to a minimum tillage regime
can take several years and during that time there are some risks
particularly during cold springs. No-till systems have been in
commercial development since 1960.
A cover crop following Corn in Iowa
2. Cover Cropping
The land were most US, rain-fed crops are grown was once a
prairie biome. That system had a mix of annual and mostly
perennial plant species. The annual crops that are now planted
in this area are only growing, and thus feeding the soil, for a
part of the year. A cover crop is planted to grow after the main
annual crop and before the next planting. A cover crop after an
annual crop is the best substitute for the perennial systems that
preceded farming of the Midwest. Cover crops can be used
either to tie up excess nutrients from the previous crop or to
generate more nutrients for the next crop (e.g. a legume). They
further reduce erosion and contribute to the storage of carbon in
soils. Most farmers recognize the benefits of cover cropping and
the main barrier to their use is the logistics of planting them
during the busy harvest season. When minimum tillage and
cover cropping are combined, the development of soil health is
optimized. Such soils are also more efficient at capturing
rainfall and at holding on to the moisture. Over time the soils
become increasingly "drought proofed" which will be of great
value in an age of climate change.
Diagram of How Auto-steer or RTK
works
3. Controlled Wheel Traffic
One problem has discouraged many farmers from continuing in
no-till. After some years without plowing, the soils can suffer
from compaction. Growers describe them as feeling "tight," and
they often feel the need to break out the plow. A more recent
technology can prevent this compaction issue. It is called
"Controlled Wheel Traffic" and it uses enhanced GPS to guide
the tractors and far implements so accurately, that no wheel
ever rolls over most of the area of the field. By preventing soil
compaction, this technology greatly reduces the production of
nitrous oxide during wet periods. Nitrous oxide is more than
300 times as potent as Carbon dioxide as a greenhouse gas, and
is often the single largest contributor to the carbon footprint of
farming.
The sort of soil maps and yield maps used for variable rate
fertilization
4. Precision Fertilization
One of the greatest ecological challenges for farming is the
efficiency of fertilizer uptake. The growing crop has a certain
pattern of uptake from the soil that changes throughout the
season. There can be periods before or after the peak plant
demand when fertilizers can be lost to surface or ground water
or to the atmosphere. In all those cases the lost fertilizer can
cause pollution and/or greenhouse gas problems. Farmers now
have the tools to minimize those losses as much as possible.
"Precision Fertilization" is really a combination of practices
through which the fertilizer is precisely placed where the plant
is likely to find it easily and applied at rates which differ across
the field. Extensive data is collected through devices like a GPS
enabled "yield monitor", by soil sampling, and even by real-time
infra-red monitoring of the nutrient status of the crop.
Specialized fertilizer applicators then apply less fertilizer or
more fertilizer as needed for each spot in the field. This not
only saves money by requiring less total fertilizer, it increases
yields by avoiding inadequate fertilization of some parts of the
field. The addition of variable rate, precision fertilization,
combined with the improved soil characteristics from the three
practices above, can almost eliminate nitrate and phosphate
pollution issues.
5. Integrated Pest Management
To achieve the sort of yields that will be needed in the future, it
will be necessary to control the yield losses that can occur
because of weeds, insects and diseases. This will by necessity
involve the use of pesticides, but by using Integrated Pest
Management (IPM), farmers can do this is a way that is safe for
humans and safe for the environment. Over the last two
decades, there has been enormous progress in finding new
pesticide options which are intrinsically low in mammalian
toxicity and very soft on the environment. They also tend to be
used at much lower rates. That can be combined with only using
pesticides if needed and fostering any degree of natural
"biocontrol" that can occur. The growers also have to be careful
to practice good "resistance management" strategies to preserve
the utility of these tools. Insect resistance traits developed
through biotechnology also help to reduce the need for
insecticide sprays.
All five of these technologies/practices are being used on a very
significant scale in modern, conventional agriculture. They are
not yet being used as widely as would be desirable, and I have
explained why not in another post.
Wheat field image from adarsh
No-till image from NRCS
Cover crop image from Iowa State University
RTK diagram from Ohio State University
Yield and soil maps from Vermont Extension
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