生活污水氮磷浓度对水稻生长及氮磷利用的影响

通过设置不同N、P浓度的生活污水进行水稻盆栽实验,研究了生活污水灌溉对水稻生长、产量以及氮磷吸收利用的影响。结果表明,在正常灌溉和不施肥条件下,污水灌溉明显降低了水稻施肥期的田面水氮磷浓度,水稻移栽后70 d左右田面水N、P浓度与不施肥处理田面水N、P浓度趋于一致;污水TN、TP浓度与水稻的生长指标和产量密切相关,生活污水灌溉提高了穗粒数、千粒重和结实率,但穗数明显减少,导致产量下降;当污水中总氮浓度达20~25 mg·L~(-1)、总磷浓度达1.0~1.5 mg·L~(-1)时,不施任何化肥条件下水稻产量即可达到常规化肥处理的95%,差异不显著,此时污水灌溉中带入的氮仅为常规施肥处理氮用量的64.1%和磷肥用量的23.2%。与常规化肥处理相比,污水灌溉提高了水稻的N、P利用效率,水稻对N、P的吸收利用与污水中的N、P浓度成正相关,且污水中的N、P存在着正交互作用,即提高P浓度促进了N的吸收利用,提高N浓度促进了P的吸收利用。在应用生活污水进行稻田灌溉时,需在分蘖期配施一定的化肥从而保证水稻高产。

Effects of the N and P concentrations in domestic wastewater on the growth,N and P uptakes of rice

In this study, rice pot experiment irrigated with domestic wastewater in different N and P concentrations was carried out to investigate the effects on rice growth, yield and uptakes of N and P. Compared to common chemical fertilizer treatment, domestic wastewater irrigation significantly decreased the concentrations of N and P in the surface water, and the N and P concentrations decreased to the level of zero-N fertilizer treatment about 70 day after transplant. The growth status and yields of rice was closely related to the concentrations of N and P in domestic wastewater under normal irrigation without chemical fertilizer input condition. The spikelet number per panicle,1000-grain weight, and filled spikelets rate were increased, but the panicle number was significantly decreased with domestic wastewater irrigation, therefore, the final yield showed a decreasion. When the TN and TP concentration in domestic wastewater was 20~25 mg·L^-1 and 1.0~1.5 mg·L^-1, the rice yield could be 95% of that with normal chemical fertilizer and the difference was not significant, but the N and P inputs by domestic wastewater were only 64.1% and 23.2% of normal chemical fertilizer treatment. The N and P use efficiency of rice was enhanced by domestic wastewater irrigation when compared to the normal chemical fertilizer treatment. The uptakes of N and P by rice were positively correlated with the concentrations of N and P in the domestic wastewater, and a positive interaction between N and P in domestic wastewater was observed. If paddy fields was irrigated with domestic wastewater, a certain amount of chemical fertilizer should be applied during tillering stage to ensure the high yield of rice.