Effect of Time and Method of Nitrogen Application and Source of Nitrogen on the Yield and Nitrogen Content of Corn (Zea mays L.)1

Abstract

AbstractFall plowdown, spring preplant, and side‐dress applications of nitrogen were compared in field experiments on Brookston clay, Brookston clay loam, and Haldimand silt loam soils. Ammonium nitrate, urea, and anhydrous ammonia were compared at 56, 112, 168, and 224 kg N/ha. Spring application (preplant or side‐dress) produced higher grain yields than fall application in all experiments regardless of the rate of nitrogen applied. Preplanting the nitrogen was as effective in increasing grain yield as the side‐dress method. Yield results with fall‐applied nitrogen were poorer on the clay soil than the loam soils. Spring application of nitrogen gave 370 to 2,610 kg/ha higher yield of corn grain than fall application on clay soils, and 200 to 1160 kg/ha higher yield of corn grain on the loam soils. No rate of nitrogen applied in the fall was found that would give the same yield as the optimum rate applied in the spring. The three nitrogen materials gave similar results whether applied in the fall or in the spring.The nitrogen content of the grain varied with the time and method of application of nitrogen. Grain from plots that received nitrogen in the fall was markedly lower in percent nitrogen than grain from plots that received nitrogen in the spring.