| Response of water quality to agricultural cultivation was investigated for the Liangwanghe River catchment of Fuxianhu Lake region in Yunnan Province of China. Two typical tillage lands-the rice-wheat rotation (R-W) and the tobacco-pea (T-P) rotation were selected and monitored. Groundwater quality and water quality of Liangwanghe River were monitored simultaneously, as well as the farmland cultivation situation at that time. It was found that cultivation activities, such as transplanting, base fertilizer applying, top dressing, draining would cause apparent elevation of concentrations of TP, PO3-4-P, TN, NO-3-N and NH+4-N of groundwater in a short time period. Nutrients adsorption by crops during different bearing periods has an obvious relationship to the change of contents of TP, PO3-4-P, TN, NO-3-N, and NH+4-N in groundwater in a long time scale. When the crops are in a peak demand for nutrients, contents of nutrients in groundwater were found to reduce obviously, and contents of nutrients may rise for other crop conditions. Contents of TP and PO3-4-P of Liangwanghe River for full cultivation periods were found to be 5.8% and 21.7% lower than those for partial cultivation periods, while contents of TN, NH+4-N and NO-3-N for full cultivation periods were found to be 11.5%, 242.6% and 9.55% higher than those for partial cultivation periods. |
