No-Till and Nitrogen Optimize
Grain Yields and Environmental Protection
By Kathryn Barry
August 23, 2000
With proper nitrogen fertilization and a no-till production system, Great
Plains dryland farmers can grow crops continuously, reduce erosion and improve
the soil's ability to store carbon, ARS
soil scientist Ardell Halvorson reported today at the
American Chemical Society's national meeting
in Washington, D.C.
Typically, farmers in the Great Plains grow rain-fed grain crops like wheat,
corn or barley one year and leave the land fallow the next. Or they may have a
three-year cycle that includes two crops before fallow. With conventional
tillage--which means mechanically tilling the leftover plant material, or crop
residue, back into the soil--a fallow period is needed to allow enough water to
accumulate in the soil to support the next crop.
But this practice leaves the soil susceptible to wind erosion. Tillage also
speeds decomposition of plant material, a process that releases carbon dioxide
to the atmosphere.
Researchers have long promoted "no-till," or planting directly
into the previous year's residue without tilling the soil, as a method to
reduce erosion and make more efficient use of water. More recently, they've
also found that no-till enhances the soil's ability to store carbon, which
helps mitigate global change by reducing the amount of carbon dioxide that
reaches the atmosphere.
Halvorson's work shows that nitrogen may mean the difference between
economic success and failure using no-till in the Great Plains. He works at the
ARS Soil-Plant-Nutrient Research
Unit in Ft. Collins, Colo.
No-till benefits the crop by increasing water held in the soil, allowing
farmers to grow crops every year without the fallow period. But nitrogen
availability limits grain yields. In several no-till studies lasting from nine
to 12 years, Halvorson found that adding sufficient nitrogen fertilizer
increased grain yields and improved water use enough to make continuous
cropping feasible. The added nitrogen also increased the amount of plant
material left as crop residue. Over time, the nitrogen/no-till combination led
to increased soil organic carbon and improved soil quality.
ARS is the chief research agency of the U.S.
Department of Agriculture.
Scientific contact: Ardell
Halvorson, ARS Soil-Plant-Nutrient Research Unit, Ft. Collins, Colo., phone
(970) 490-8230, fax (970) 490-8213,