Effects of chlorination on emitter clogging and tomato yield and nitrogen uptake in a drip irrigation system with sewage effluent

摘要

Chlorination is the most common practice used in the prevention and treatment of emitter clogging caused by algae and bacteria. Field experiments were conducted in a solar-heated greenhouse to investigate the effects of chlorine concentration and injection frequency on emitter clogging of drip system with sewage effluent and tomato yield, quality and nitrogen uptake. A multiple regression model was derived to predict nitrate content by soil electrical conductivity, water content and temperature, andused to investigate the effects of chlorination on nitrate dynamics and nitrogen uptake. No significant emitter clogging was detected and the influence of chlorine concentration and injection interval was slight. This might attribute to the relatively short period of operation time. Irrigation with sewage effluent resulted in an increased nitrate content profile in growing season. The increase in chlorine concentration and injection interval led to a significant increase of nitrate content in upper 15cmlayer. Chlorination decreased the total nitrogen of plant stem. No significant influence was found on tomato yield and quality. The results obtained from this study suggested that injection of chlorine with an input concentration of less than 50 mg/L and an interval of larger than two weeks do not impose a negative influence on tomato growth, although the injection of chlorine may restrain the nitrogen uptake of plant.