3/29/2002 The No-Till Boom Abroad
From the pages of the March 2002 edition of Top Producer magazine.
By Darrell Smith
Economics and the need for erosion control make no-till routine in South American. Some U.S. farmers could borrow their practices.
If you launch a farming operation in South America, you'll probably no-till. The practice is surging in countries such as Brazil, Argentina and Paraguay. In the frontier regions of Brazil, no-till approaches 100%.
"No-till planting increased 20-fold between 1990 and 2001 in these countries," says Rolf Derpsch. He has helped develop no-till practices in there for more than 30 years, for an international development agency and as a private consultant.
In the United States, the rate of no-till adoption is almost stagnant, except among soybean growers. "Although the U.S. has more total land under no-till [than South America], it accounts for only 17.5% of cropland acres," adds Dan Towery of the Conservation Technology Information Center (CTIC).
Economics (high input costs and no government support) and erosion control pushed South American farmers toward no-till. "Studies using a systems approach show no-till is more profitable," says Derpsch.
Since Brazilian farmer Frank Dijkstra of Ponta Grossa, Paraná, began no-tilling in 1977, for example, corn yields have doubled, on 30% less fertilizer. Soybean yield has increased by more than 50%, with only half as much fertilizer.
By preventing erosion during intense South American rainstorms, no-till retains nutrients, says Bruno Alesii, manager of technology development for Monsanto and chairman of CTIC. "Although South American soils often are deep, nutrients are concentrated in the top few inches," he explains.
South American no-tillers apply fewer herbicides because they use diversified rotations and an array of cover crops. Covers are central to South American no-till success, says Derpsch. "Studies show the highest economic returns come from a combination of no-till, rotations and cover crops," he says. "In some cases, we have been able to farm up to three years without applying herbicides."
Besides crowding out weeds, the residue from cover crops builds soil organic matter content. No-till alone can't do that in tropical and subtropical climates because crop residues decompose too quickly. "Our farmers understand a steady decline in soil fertility is unavoidable if they intensively till," says Derpsch. "The moment organic matter begins to decline, a system becomes unsustainable."
Rather than kill covers with herbicides, South American growers roll them flat with "knife-rollers" with chopper-like blades. They no-till plant in line with the direction they rolled (never across), using coulters and planting units similar to those on U.S. no-till planters.
Borrowable. Some South American no-till practices may transfer to the southern United States. Growers there are desperately seeking ways to boost yields and reduce their high cost of production, which run as high as $8 to $10 per bushel on soybeans, according to USDA.
In Auburn, Ala., USDA-ARS soil scientist Wayne Reeves has documented that inserting a cover crop into a no-till rotation increases organic matter, reduces compaction (which occurs on some soils even without tillage) and improves water infiltration.
Letting rye or black oats (popular South American covers) start to flower, then hitting them with a knife-roller, Reeves gets complete kill without herbicides. He kills the cover four weeks ahead of planting, to ensure it doesn't deplete soil moisture and there's no lingering allelopathic effect (the ability of some plants to kill others).
Outside of the South, U.S. farmers won't want to copy South American no-till technology because conditions are different, says Derpsch. "But you can adapt it," he says. "The principles of no-till, rotation and cover crops apply here, also."
Here are some reasons Rolf Derpsch believes U.S. farmers have been slow to use no-till: No systems research. "There is a lack of economic evaluations of no-till with a systems approach. Some comparisons say conventional tillage is more economical; I think those studies are wrong. With no-till, you save time, labor and fuel, and reduce machinery investment. And the studies did not value the soil lost in conventional tillage, the decrease in fertility and organic matter or the cost of cleaning sediment from water."
Mindset. "Neither farmers nor landlords recognize the value of crop residues on top of the soil."
Misplaced incentives. Financial incentives should be shifted away from construction practices such as building terraces to promoting no-till. "As long as farmers use rotational tillage, they never will experience the full benefits of a no-till system."
Erosion rates too high. "Allowable soil loss rates often are set too high. If losses are higher than the rate of soil regeneration, a system is not sustainable."
Mixed signals. Derpsch notes that he read a newspaper article that was mostly favorable to no-till. It ended with a quote from a tillage implement manufacturer saying no-till has some merit, but it must be managed in rotation with tillage, he says. "From my 31 years of experience, this is absolutely wrong."
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