“No-till” Soybeans Following Wheat
There is a sub-set of farmers who have been practicing a much more sustainable form of agriculture for decades and we are coming up on the 50th anniversary of it’s beginnings. I want to start writing about this event early because many environmentally-conscious folk are not aware of this hugely significant “revolution” that has occurred in agriculture over the past half century. No, I’m not talking about “Organic Farming.” That movement is about a decade older in the US and has had a much smaller impact. I’m talking about “No-till” agriculture and variants that are focused on reducing the amount of “tillage” or “plowing” that are needed to farm.
For many centuries, plowing and tillage have been key practices for agriculture.
That was how a good “seedbed” was prepared and that was how weeds were controlled. But just because a practice is ancient does not mean it is good. Plowed land is much more subject to water and wind erosion and plowing combined with annual cropping has lead to the depletion of carbon stores in our soils.
History of No-till
In 1943, Edward Faulkner wrote a book titled “The Plowman’s Follyin which he questioned the reasons for plowing. That was a very controversial idea at the time, but by 1960, researchers began to try to find a way to farm that didn’t involve disrupting the soil. The crop “residue” was chopped and left on the soil surface. The next crop was “drilled” into that matrix. Weeds were not controlled by mechanical disruption of the soil, but by the use of herbicides (and yes, there are safe and environmentally benign ways to do that). Between the work of USDA and University scientists, progressive growers and equipment and chemical companies, this concept was turned into an economically viable option that has now been adopted on around 66 million acres of US cropland (20% of the total) and on 260 million acres world-wide (excellent but fairly large slide set about this from no-till experts Rolf Derpsch and Theodor Friedrich). This system has proven to have the following advantages:
- Water and wind erosion diminished to near zero (with the added benefit of reduced fertilizer and pesticide residue movement that was associated with that soil movement)
- Reduced fuel use and the greenhouse gas emissions associated with it (e.g. 66% reduction in corn)
- Labor efficiency (e.g. an individual grower can plant more acres or can reduce labor expense)
- Improvements in soil quality in terms of aggregate stability, rainfall capture efficiency (less runoff) and water holding capacity
- Increased soil carbon (particularly if paired with “cover-cropping”) that can “sequester” carbon dioxide from the atmosphere
- Increased biodiversity both above and below ground (e.g. earthworms)
- Better plant association with mycorrhizae (soil fungi which help plants obtain nutrients)
- Lower nitrous oxide emissions on most soils (a potent greenhouse gas)
No-till and other “Conservation tillage” systems combined with cover-cropping is the most sustainable option for agriculture today. Organic producers (who are more likely to practice cover cropping, to their credit) don’t really have the option of reduced tillage. There are some efforts in that direction, but they are not practical on any significant scale. Organic has been focused on building soil organic carbon and that is an excellent thing to do, but part of the way they do it, importing large quantities of compost or manure, is problematic from a greenhouse gas perspective as I described in a previous post. Reduced tillage and cover cropping is much more like the way that soils are built in a natural system.
So in the spring of 2010 those of us who are focused on sustainable agriculture will celebrate the work that was started a half century ago. Maybe a new market of carbon off-sets will help spur even more conversion.
No-till Soybeans Image from NRCS. Traditional plowing image from IRRI.