Nation's worst erosion transformed by no-till

Conservation tillage — once derided as “trash farming” — has made substantial inroads with producers in the Mid-South. Perhaps no place has it been more successful than in Tennessee, where pioneering research has been done and where no-till is now the preferred method for most farmers. In fact, says H. Paul Denton, Extension professor of soil management with the University of Tennessee Extension Service at Knoxville, “No-till has become the conventional tillage system for corn, soybeans, and cotton in our state. In my talks, I don't even use the term ‘conservation tillage’ any more.”

No-till is now used on 60 percent of the state's cotton, 65 percent of the corn, and 70 percent of the soybeans, he told attendees at the 25th anniversary Southern Conservation Tillage Conference for Sustainable Agriculture at Auburn University.

Quite an achievement, considering that in 1977 Tennessee's highly erodible soils held the dubious distinction of having the highest per-acre erosion loss in the nation, due chiefly to the year-after-year, decade-after-decade tillage practices employed by farmers and scant use of winter cover crops to keep fragile soils from washing into streams and rivers.

“The average rate of erosion for all cropland was 15 tons per acre per year,” Denton says, “but on upland soils it often exceeded 50 tons per year, with some as high as 100 tons.” Annual tillage destroyed soil structure, caused a loss of water storage capacity for crop use and to compensate for drought, and resulted in a permanent loss of crop yield potential.

In the intervening years, however, with changes in farming practices, those horrible soil erosion rates have been slashed by 60 percent or more, soil quality has improved, and crop yields have moved upward.

These accomplishments didn't come easily, Denton notes. Farmers were reluctant to change from traditional methods; conventional equipment was not readily adaptable to no-till; the herbicide lineup was limited; and there were concerns (which proved unfounded) about insects/diseases and an unmanageable buildup of mulch over time.

Thanks to the pioneering work and dogged determination of men like UT Professor Henry Andrews and later, Tom McCutcheon and John Bradley at the Milan Experiment Station, there was extensive research and on-farm trials in no-till and its various permutations. As commercially-manufactured machinery designed for no-till applications gradually became available, more farmers began giving it a try. The Milan No-Till Field Day, started by McCutcheon in 1981 to spotlight research and accomplishments, has become a major event.

“The conservation compliance provisions in the 1985 farm bill gave no-till a considerable boost, especially for cotton,” Denton says. “While conservation compliance didn't require no-till, the cost advantages quickly became apparent.” In the 1998-2001 period, no-till got another major boost with the advent of genetically modified Roundup-tolerant varieties, which “greatly simplified weed control.

While there are still some concerns related to no-till, including resistance of marestail to Roundup, lack of adequate biomass in crops such as cotton and corn, and insect problems in no-till wheat, Denton says on the whole the system that farmers once made fun of “is very successful.”

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