Impact of Reclaimed Water on Crop Safety

Pot experiments in 2 consecutive years of maize (Zea mays L.) and soybean (Phaseolus vulgaris L.) irrigated with reclaimed water were carried out to investigate the impact of water quality (all reclaimed water, mixed water of fresh and reclaimed water, and alternating irrigation of fresh water and reclaimed water) and irrigation phase of the reclaimed water (whole growing seasons, early phase of growing season, and later phase of growing season) on crop's growth, quantity, quality, and soil properties. The results showed that irrigation with the reclaimed water in early phase of growing season withheld maize's growth to some degree but irrigation in later phase (after jointing ) boosted maize's growth and grain yield. Irrigation with the reclaimed water and the mixed water in whole growing season enhanced soybean's growth and grain yield. Irrigation with the reclaimed water had no significant adverse effect on conventional nutrients and mineral elements in the maize and soybean kernels. The concentrations of Pb and Cd in the two crops met the National Standard for Crop Safety but irrigation with the reclaimed water potentially increased Cd concentration in the soybean grain. Significant increases of pH and EC values and accumulation of Pb were observed in soil after irrigations with the reclaimed water in whole growing season though the soil quality still complied with the National Class A Standard for Soil Quality. Irrigation with the reclaimed water in a time period of 2 years showed no significant adverse effect on the soil quality.