紫色水稻土磷素动态特征及其环境影响研究

Dynamic Characteristics of Phosphorus in Purple Paddy Soil and Its Environmental Impact

采用单排单灌的田间试验,研究了施用化学磷肥和有机肥对水稻生长期稻田径流水和田面水中磷素动态变化的影响,并对其可能产生的环境风险进行了分析.结果表明,随着施磷水平的提高田面水磷含量升高,施肥24 h后各处理田面水磷素含量最高,总磷（TP）含量在0.928～3.824 mg/L之间;前30 d田面水磷含量波动大,TP平均含量在0.259～1.433 mg/L之间,超过水体富营养化的临界值,在此期间应避免排水和中耕等田间管理;40 d之后田面水磷含量缓慢下降,60 d后趋于稳定,且含量较低.径流水各形态磷的含量和流失负荷随着降雨强度和磷肥用量的增加而增加,径流水中溶解磷（DP）占TP的50%以上,稻田土壤磷素淋失以DP为主,磷素流失负荷在0.358～2.579 kg/hm^2之间.稻田磷素流失也受施肥方式的影响,施用牛粪比施用秸秆更容易导致磷素的流失,施用牛粪处理磷素流失负荷比施用秸秆处理高40%,化学磷肥与秸秆配施稻田磷素流失负荷和表观流失率显著降低,秸秆与磷肥配合施用是减少稻田磷素流失的较好措施.

Tbe dynamic characteristics of phosphorus （P） in the surface water and runoff of paddy field with different P fertilizing treatments were investigated using the field experiment under the independent irrigation system as well as its environmental impact. The results showed that the concentration of total phosphorus （TP） in the surface water increased as the fertilizing amounts enhanced and reached the peak values after 24 h for all treatments in range of 0.928 ～ 3. 824 mg/L. And the fluctuation of TP concentration in surface water was drastic during the first 30 days with the average contents of 0,259 ～ 1.433 mg/L which exceeded the critic values of eutrophication. Therefore, the field managements such as inter-tillage and drainage should be avoided during the time. After 40 days, the TP concentration declined slowly and then came to stabilization with low values after 60 days. The contents of different P forms in the runoff water increased with the improved amounts of precipitation and fertilizing and above 50% was dissolved phosphorus （DP）. The DP was the dominant one in the P loss of the purple paddy soil and the loss load changed between 0.358 and 2.579 kg/hm^2 . Additionally, the P loss more easily occurred for the treatment of utilizing the cattle manure than that of straw, approximately 40% of loss load higher. Both the loss load and apparent P loss ratio evidently declined with the treatment of fertilizer combined with straw, suggesting that it was the better measure for reducing the P loss in the paddy field.