Experiments were conducted at Tucson, Arizona to study effects of treated municipal waste water on growth, fiber, acid-soluble nucleotides, protein, and amino acid content in grain from wheat (Triticum aestivum L.). Wheat grain was grown in two soil types, (i) Comoro sandy loam, and (ii) Grabe silt loam. Three irrigation and fertilizer treatments were used: (i) well water plus suggested amounts of nitrogen, phosphorus, and potassium (112, 35, and 1 kg/ha of N, P, and K, respectively); (ii) well water plus N, P, and K from commercial sources in amounts equal to those found in waste water (224, 73, and 140 kg/ha of N, P, and K, respectively); and (iii) waste water from an activated sludge sewage plant (224, 73, and 140 kg/ha of N, P, and K, respectively).
Average number of heads per unit area and grain yield were higher in wheat plots that received waste water than they were in plots that were grown with well water and suggested N, P, and K. Average days from planting to maturity, plant height, seeds per head, and seed weight were similar for the three irrigation and fertilizer treatments. Wheat grain grown with the three irrigation and fertilizer treatments contained similar amounts of total fiber and acid-soluble nucleotides. Grain grown with waste water contained more total protein than did grain produced with well water plus suggested amounts of N, P, and K. Wheat grain that received only waste water contained more alanine, histidine, isoleucine, and proline than did grain produced with well water plus suggested N, P, and K or well water plus N, P, and K equal to waste water. Grain grown with the three treatments contained similar amounts of cystine, methionine, and threonine in all instances. High yields of high quality grain were obtained from wheat irrigated with treated municipal waste water in the southwestern United States.