No-till practices conserve topsoil, water
Only the summers of 1934 and 1936 were hotter and drier. While 2002 was devastating to many farmers' crops, it was nothing like the environmentally disastrous days when dust clouds rolled across the plains.
Much of the credit goes to local soil and water conservation districts and state and federal conservation agencies. Over the years, they have educated farmers to apply conservation systems and worked for programs that have converted some of the most vulnerable cropland to grassy conservation reserves. Other practices, such as winter cover crops and planting of windbreaks, also are protecting our soils.
Another major factor has been the movement toward conservation tillage, or no-till. With no-till, instead of plowing and disking their fields, farmers leave the stubble and debris of the previous crop on the soil surface.
A recent report by the Conservation Technology Information Center documents the many environmental benefits of conservation tillage, including its ability to reduce erosion and preserve soil moisture. According to the private, nonprofit center, based at Purdue University, no-till has the potential to recreate the soil cycle characteristic of the native prairies.
"In the prairies, the annual cycle of grasses created a deep layer of litter, which protected the soil from wind and water erosion and temperature extremes," the report said. "Nearly two centuries of intensive tillage later, that cycle has been radically altered.... Within the past decade, however, many farmers have begun to recreate the cycle that once characterized the prairie soils."
The report, released at the World Food Prize Symposium in Des Moines, Iowa, cited research that compares the moisture content in no-till and conventionally tilled soils.
No-till fields allow rainfall to seep into the soil rather than washing off and flowing downstream. The layer of surface litter also reduces evaporation, thus preserving soil moisture, which gives crops a fighting chance when rainfall is scarce. Conservation tillage also improves irrigation efficiency, because more of the applied water infiltrates the soil to be used by crops. This means less demand on aquifers, a benefit easily recognized by cities where water-use curbs were ordered in 2002.
No-till also protects the soil, reducing erosion by 90 percent or more, according to the center's report. As more farmers have adopted conservation tillage, erosion on U.S. cropland has decreased by 30 percent or more since 1982, saving almost 1 billion tons of soil per year.
What does it mean to save topsoil? Obviously, we protect the foundation of our food production. Conservation also means that sediment does not end up in our rivers and lakes, diminishing the storage capacity of these drinking water sources. When municipal reservoirs hold less water, they more quickly reach critically low levels in times of drought.
Unfortunately, not all farmers apply conservation systems. For decades, farmers have relied on tillage to control weeds, and many are reluctant to give up that security. The Conservation Technology Information Center credits the advent of herbicide-tolerant crops developed through biotechnology with lessening the concern for many growers, pointing out that much of the growth in no-till has occurred in cotton and soybeans, where the new technology is available.
The study predicts more conservation tillage as additional crops are made herbicide tolerant. While new technologies will help, many farmers will remain reluctant to invest in equipment, learn a new system or take what they perceive to be a risk.
The 2002 farm bill includes funding for the new conservation security program to encourage conservation practices on millions of new acres of working farmlands. Congress approved the program, and President Bush signed it into law. But it is at risk of being reduced to a pilot project and limited to one state. That would be a big mistake, especially if we are heading into a dry cycle like Tom Joad and his generation knew.
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