Nitrate Accumulation in Soils and Loss in Tile Drainage Following Nitrogen Applications to Continuous Corn

Abstract

AbstractNitrate‐N concentration in tile water, loss from tile lines, and accumulation in soil profiles were determined following each of three annual applications of 20, 112, 224, and 448 kg N/ha to continuous corn (Zea mays L.) grown on a Webster clay loam (Typic Haplaquoll) in southern Minnesota. Plots were isolated to a depth of 1.8 m with plastic to allow an accurate assessment of the area drained. Water flow through the tile lines occurred annually for approximately 6 weeks in the period from mid‐April through early July and constituted an equivalent from 20 to 46% of the precipitation during the flow periods and from 7 to 22% of the annual precipitation during the 3 years studied.There was relatively little increased NO3‐N accumulation in the soil profile or loss from tile lines at the recommended application rate of 112 kg N/ha compared to that for the check treatment. Nitrate‐N losses through tile lines in 1975 (after 3 years treatment) were 19, 25, 59, and 120 kg/ha for the 20, 112, 224, and 448 kg N/ha applications, respectively, which had NO3‐N accumulations in the 0–3 m soil profiles of 54, 100, 426, and 770 kg NO3‐N/ha. Maximum NO3‐N accumulation in the soil profiles occurred at a depth of about 1 m with little evidence of movement below about 2.2 m.