Yield and elemental composition of wheat grain as influenced by source and rate of nitrogen

Abstract

Application of sewage sludges to winter wheat (Triticum aestivum L.) is a possible mechanism to supply nutrients to the crop while simultaneously reducing the need for more expensive and less desirable disposal strategies. Research was conducted during 1986 and 1987 to determine the effect of fall applied sewage sludges on yield, N recovery, and elemental composition of wheat grain. The study was conducted in a corn (Zea mays L.)‐wheat‐soybean [Glycine max (L.) Merr.] rotation located on a Suffolk sandy loam soil (coarse, loamy, siliceous, thermic Typic Hapludult). The N treatments applied consisted of 0 (control), 30, 60, and 90 kg N ha^‐1 from UAN solution applied in the spring and two anaerobically digested sewage sludges (one lime conditioned and the other lime stabilized) designed to supply 80 kg of plant available N ha^‐1 applied in the fall. Twenty kg of N as UAN solution were applied in the fall when the wheat was seeded to all treatments except the control and the sewage sludge treatments. Grain yield and N uptake were linearly related to inorganic N application. Ninety‐nine percent of the variation in yield and N recovery could be attributed to rate of inorganic N application in the spring. Fall application of sewage sludge was just as effective as spring application of inorganic N and resulted in greater N uptake than spring application of inorganic N. There were no differences in yield and N uptake between polymer conditioned and lime stabilized sewage sludges treatments and in N, P, K, Ca, Mg, S, Mn, Zn, and Cu concentrations in the wheat grain with varying levels of inorganic N application. Sewage sludge increased the N, P, Zn, and Cu concentrations in the wheat grain. The concentrations of Mn, Zn, and Cu were lower in the wheat grain at the higher soil pH from lime stabilized sewage sludge application than from polymer conditioned sewage sludge application.