Effects of Sewage Sludge on Yield and Quality of Wheat Grain and Straw in an Arid Environment

Abstract

A 6-year experiment (1978) through 1983) was conducted at the Mesa Agricultural Center, Mesa Arizona, U.S.A. to study the effectiveness of dried sewage sludge as a fertilizer source for the production of grain and straw from 'Zaragoza' wheat (Triticum aestivum L.). Three fertilizer treatments were applied each year before planting on a laveen loam soil, a member of the coarse-loamy, mixed, hyperthermic Typic Calciorthids. The treatments consisted of: (1) suggested rates of nitrogen (N), phosphorus (P), and potassium (K) in Arizona-160, 81, and 0 kg ha⁻¹ of N, P₂O₅, and K₂O; respectively; (2) 10 Mg ha⁻¹ of dried sewage sludge to supply N in amounts equal to the suggested rate; and (3) inorganic fertilizer to provide N, P, and K in amounts equal to those applied in the sewage sludge-160, 310, and 36 Kg ha⁻¹ of N, P₂O₅ and K₂O; respectively. Average number of days from planting to harvest, plant height, grain yield, grain volume-weight, and grain/straw ratio were similar for wheat grown with all fertilizer treatments. In vitro dry matter disappearance (IVDMD) and total protein concentration in wheat grain were similar for all fertilizer treatments. In vitro dry matter disappearance and total protein concentrations in wheat straw grown with sewage sludge alone were higher than they were in straw from wheat grown with suggested N, P, and K from commercial fertilizer. Wheat grain and straw from all fertilizer treatments contained relatively low concentrations of cadmium, zinc, copper, lead and nickel. Concentrations of N, P, K, Na and total soluble salts were higher in soil fertilized with dried sewage sludge for 6 years than they were in the original soil.