SOIL EROSION SOLUTIONS
So what is the solution to the dire circumstances concerning soil erosion pointed out by Jeremy Grantham in Soil Erosion?
Grantham says it is…
“So as not to end too gloomily, I have saved the best news for the end; news so good that Cornucopians can jump for joy and gloomy Malthusians can think “What undeserved luck!” Most huge improvements in anything take equally huge investments of time, energy, and capital. This one, which reduces erosion rates from way over sustainability to acceptable levels, requires very little except a willingness to change one’s ways, a characteristic not always in great supply in any group, including farmers. No-till farming, developed in recent decades has, after a slow start, been spreading very rapidly in South America. It is now used in more than 50% of all arable land there, which, given the heavy rains in much of the area, is just as well. In the U.S., the adoption of no-till has very recently accelerated and it now accounts for more than 35% of farmland according to the U.S.D.A. In general, it is growing elsewhere, albeit slowly, and hardly at all in Africa. The bad news is that globally, despite its advantages, it makes up only a 5% shareof grain production. Just as it sounds, no-till leaves the crop residue on the field and the following year, instead of plowing up the ground, a rotating wheel pierces the ground every few inches and plants a seed, sometimes together with a precisely measured dose of fertilizer. After a few years, the mat of ground cover massively reduces the erosion caused by heavy rains: the average academic study reports more than an 80% reduction, with the highest being 98% and the lowest 50%. In one fell swoop, the erosion problem can be effectively resolved.
Protecting the soil may be the biggest single advantage of no-till, but there are several other important ones. When soil is washed or blown away, it is the very top soil that goes, and this is the soil that carries much of the nutrients that have been added at no small cost. About one-third of the fertilizer is wasted. This was an irritant when potashwas $175 a ton five years ago. At the more recent price of $420 a ton, it is a serious saving – enough to get farmers’attention. With no-till, there are incremental nutrients in the accumulated stubble, which further reduces costs and,more importantly, reduces the load on critical limited fertilizer resources. Water retention in the soil also greatly increases because the effects from full-scale plowing, which exposes the moist soil to the sun, are mitigated by no-till. When rain is plentiful and evenly spaced, there is little difference between the two systems in this respect, but when rains are scarce or there is full-scale drought, the extra moisture protected by the ground cover can make a big difference to productivity. So life is easier for the soil, whether it is a flood or a drought; a particularly compelling case in these days of increased weather instability. Finally, the quality of the relatively undisturbed soil improves as the number of microbes, bacteria, fungi, and other living critters steadily multiplies. This in turn arguably increases the carbon density of the soil and definitely further increases the water retention capacity and the amount of micronutrients, which, under full plowing, basically fall to zero. It is widely believed that micronutrients make food healthier and that their chronic absence in modern food has not been healthy for us, molded as we are by tens of thousands of years of eating more complicated foods. All in all, no-till is like a gift from Ceres and single-handedly would remove or long postpone most of our long-term productivity problems. With no-till, productivity typically drops slightly in the first few years, but then slowly increases. Conversely, with high-erosion plowing, it slowly decreases, with potentially severe consequences over very long periods. Another disadvantage of no-till is that it requires more insecticide, especially in the first few years,which has environmental and financial costs. Researchers, though, increasingly believe that most of this increase can be removed by ne-tuning crop rotation, cover crops, and other “engineering” tricks. The bottom line seems to be that if we adopted no-till globally for a great majority of our grain crops, the only serious threat to agricultural productivity would be from the very long-term shortage of mined fertilizers, with even that threat much postponed. Additional efforts with soil enhancement and full-scale organic farming could further improve fertility and lower the need for “outside” fertilizer, but that is a topic too complicated and controversial to be covered here.” – Jeremy Grantham.
Geoff Lawton of the Permaculture Research Institute of Australia is a world-leading expert on permaculture and has undertaken impossible-seeming projects such as the Greening the Desert project in the youtube clip above. Catch more of Lawton’s incredible knowledge in action at the Agricultural Solutions page.