Commercial Production of Wheat Grain Irrigated with Municipal Waste Water and Pump Water

Abstract

Experiments were conducted in southern Arizona to study the effects of irrigating wheat (Triticum aestivum L.) with a mixture of pump water and waste water and with pump water alone on wheat growth, grain yield, grain quality, soil properties, and irrigation water quality. In small plot research, wheat irrigated with the pump water-waste water mixture produced taller plants, more heads per unit area, heavier seeds, higher grain yields, and higher straw yields than did wheat grown with only pump water. When large fields were compared, wheat grown with the pump water-waste water mixture had taller plants, more lodging, lower grain volume-weights, and higher grain yields than did wheat produced with pump water. The pH and exchangeable sodium of soil irrigated with pump water alone or the pump water-waste water mixture were similar. Soluble salts and nitrate-nitrogen were higher in soils irrigated with pump water than they were in soils irrigated with the pump water-waste water mixture. Extractable phosphorus was higher in soils irrigated with the pump water-waste water mixture than in soils irrigated with pump water. Total soluble salts and nitrate-nitrogen were higher in pump water than they were in the pump water-waste water mixture; however, the pump water-waste water mixture had higher levels of total nitrogen and phosphorus than did pump water. The higher grain yields obtained when wheat was irrigated with the pump water-waste water mixture than were produced when wheat was grown with pump water alone probably resulted from lower concentrations of soluble salts in the pump water-waste water mixture than were present in pump water.