Tillage and Nitrogen Fertilization Influence Grain and Soil Nitrogen in an Annual Cropping System

Authors

Ardell Halvorson, USDAFollow
Brian J. J. Wienhold, University of Nebraska-LincolnFollow
Alfred L. Black, USDA

Document Type

Article

Date of this Version

2001

Citation

Agron. J. 93:836–841 (2001).

Abstract

Increasing the frequency of cropping in dryland systems in the northern Great Plains requires the application of N fertilizer to maintain optimum crop yields. A 12-yr annual cropping rotation [spring wheat (Triticum aestivum L.)–winter wheat–sunflower (Helianthus annuus L.)] under dryland conditions was monitored to determine the influence of tillage system [conventional till (CT), minimum till (MT), and no till (NT)] and N fertilizer rate (34, 67, and 101 kg N ha^-1 ) on N removed in grain and annual changes in postharvest soil NO₃–N. Nitrogen removal in the grain increased with increasing N rate in most years. Total grain N removal was lowest with NT at the lowest N rate and highest with NT at the highest N rate compared with CT. Total grain N removal after 12 cropping seasons was 144, 84, and 61% of the total N applied for the 34, 67, and 101 kg N ha^-1 fertilizer rates, respectively. Residual soil NO3–N levels were not affected by N rate or tillage system in the first 3 yr, but they increased significantly following consecutive drought years. Residual NO₃–N in the 150-cm soil profile tended to be higher with CT and MT than with NT. Soil NO3–N movement below the crop root zone may have occurred in 1 or 2 yr when precipitation was above average. Results indicate that NT, with annual cropping, may reduce the quantity of residual soil NO₃–N available for leaching compared with MT and CT systems.