Tillage and nitrogen management systems can have a significant effect on nitrogen use by corn and nitrate movement through the soil profile.
Potential water quality and nitrate loss problems associated with conventional tillage and fall-applied nitrogen prompted this study with the objective to evaluate strip-tillage effect on corn nitrogen uptake and nitrate movement through the soil profile compared with chisel plow and no-tillage systems.
The three tillage systems implemented in this study were strip-tillage, no-tillage and chisel plow, along with two nitrogen application timings (fall and spring) of about 150 pounds per acre for corn in a corn–soybean rotation on two Iowa fields in 2001 and 2002.
The three tillage systems were implemented every year for both corn and soybeans. Crop response, nitrogen uptake and other soil-nitrate measurements were conducted on a randomized complete block design experiment.
Grain yields and grain nitrogen uptake showed no significant improvement under strip-tillage compared with no-tillage or chisel-plow systems.
Tillage and nitrogen treatments caused no significant differences in nitrate accumulation at the lower depths of the root zone which was 4 feet below the surface of the soil.
Strip-tillage and no-tillage resulted in lower residual soil-nitrate buildup than chisel plow in the 0-to-4-foot profile of the soil after 2 years of tillage. Tillage and nitrogen treatments did not cause significant differences in nitrate concentration in water leachate collected at the 4-foot depth.
Editor's Note: This is a summary of an article published in Agronomy Journal in 2004 by Mahdi Al-Kasi and Mark Licht of the Iowa State University Department of Agronomy.