Water Management Effects on N-Use by Corn and Sugarbeets

Abstract

ABSTRACT A3-year field study was conducted to determine the effects of surface irrigation, depth to water table and rate of N-fertilization on dry-matter forage yields, N-uptake of crops, and soil-N levels. Corn (Zea mays L.) and sugarbeets (Beta vulgaris L.) were grown on a complex of Aquic Haploboroll, Typic Calciaquoll, and Typic Haplaquoll soils (Hecla-Arveson-Fossum Associations) with average water-table depths of 147, 203, and 229 cm deep during the growing season of May 15-September 30. All combinations of surface irrigation and N level occurred with each water table. Half of the plots were surface (sprinkler) irrigated and half were not. Available N (soil plus fertilizer) levels were established each spring at 56, 112, or 224 kg N/ha. The soil supplied considerable N because the harvested corn forage and sugarbeet roots contained more N than was applied during the three years. Yields, N-uptake and the proportion of available N taken up by plants were the greatest at the shallowest water table. Surface irrigation of soils with the 203 and 229 cm water tables increased yields and N-uptake. Yields and N-uptake were increased by N-fertilization. The fraction of available N taken up by crops was greatest at the 112 kg N/ha rate. The data from this study suggest that both N and water applications need to be carefully chosen to optimize profits when a nonsaline watertable is less than 203 cm below the soil surface..