Dry matter production and nitrogen utilization in cropping systems with grass, lucerne and maize. 2. Nitrogen yield and utilization.

Abstract

The N yield and the N use efficiency were studied in a 3-year experiment with various cropping systems of Lolium perenne, Medicago sativa and maize. N yields of L. perenne and maize were about 450 and 200 kg/ha, resp. N yields of M. sativa ranged from about 400 to 600 kg/ha depending on crop age and weather conditions. N fixation rates of M. sativa were assessed in 1982 and ranged from 107 to 507 kg/ha for high (450 kg N/ha) and no N fertilization, resp. The after-effects of 1-, 2- and 3-year crops of L. perenne, M. sativa and maize on the DM and N yields of a test crop of maize were measured. Depending on the age of the preceding L. perenne crop, annually supplied with 450 kg N/ha, the N after-effects ranged from 120 to 175 kg/ha. The after-effect of a previous cropping with M. sativa was independent of the N dressing and ranged from 140 to 175 kg/ha. For comparison, the after-effect of a preceding maize crop ranged from 90 to 110 kg/ha. Mineral soil N reserves were determined in spring and autumn. (Abstract retrieved from CAB Abstracts by CABI’s permission)