| In recent years, with the increasing amount of chemical fertilizer, nutrient run-off loss in farmland has become increasingly serious. Agricultural non-point source pollution in Chaohu Lake Basin area was concerned by environmental protection departments of agriculture, as well as government departments. The environmental pollution problem caused by farmland nutrient loss in Chaohu Lake Basin area is getting worse, but the exact circumstances, as to the exact quantity about the nitrogen and phosphorus loss in farmland , which we all do not know. In view of the above issues, this study carried out monitoring and measurement on the nitrogen and phosphorus run-off loss.The study used the method of field monitoring in situ, built the run-off pools in the farmland, which can collect the run-off water. The experimental farm was in agricultural science and technology demonstration bases of Juchao District in Chaohu City, which also was Anhui rice pest integrated control demonstration area. The model of cultivation for monitoring was the wheat-paddy rotation. The test of Wheat and rice designed six processing respectively, which were the blank control experiment (No fertilizer), conventional fertilization, optimized fertilization, reduction 30% in nitrogen, reduction 50% in phosphorus and straw. After rainfall, measuring the Volume of water generated by runoff, collecting water samples, assaying the TN, NH4+-N, NO3--N, TP and DP in the runoff water.By combined with the fertilizer usage, measured the situation of runoff loss of the nitrogen and phosphorus in wheat-paddy rotation field, so to grasp the characteristics and rules of nutrient loss and pollution in this main planting system, and to change the improper production fashion and reduce the environmental pollution in the process of agricultural production in Chaohu Lake Basin. Finding out the basic situation of pollution, for the establishment of agriculture and environmental protection-related policy provide decision-making basis,and for the agricultural non-point source pollution control and governance in Chaohu Lake Basin provide scientific basis。The results that got from the monitoring test are summarized as follows:1. The growth situation of crop between the six different Processing showed that: no fertilizer had a significant impact on the crop early growth, not only a few stems, plant height is also lower, and ultimately affect the ear length, kernel number and other relevant production factors; by nitrogen and phosphorus reduction Processing also produced some adverse effects on the crop growth, leading to reduction of crop yield.Wheat yield showed: straw≥optimized fertilization>conventional fertilization>reduction 30% in nitrogen> reduction 50% in phosphorus>No fertilizer; Rice yield showed: straw>optimized fertilization>reduction 30% in nitrogen>conventional fertilization>reduction 50% in phosphorus>No fertilizer. Straw showed some advantages in the crop growing period. The crop yield may also explain that the straw has certain promoted value. Reduce the quantity fertilizer while straw.2. The N, P and K absorbing capacities by crops explained that more N are assimilated by the wheat, more P and K are assimilated by the rice. Between the six different Processing showed that absorbing capacity of N: optimized fertilization>straw> conventional fertilization>reduction 30% in nitrogen>reduction 50% in phosphorus>No fertilizer; P: optimized fertilization>straw>reduction 30% in nitrogen>conventional fertilization>reduction 50% in phosphorus>No fertilizer; K: reduction 50% in phosphorus> reduction 30% in nitrogen>optimized fertilization>straw>conventional fertilization>No fertilizer. The use factor of fertilizers has the direct relation with the N, P and K absorbing capacities by crops. The use factor of N was higher by wheat; and of P and K was higher by rice. The use factor of N, P and K fertilizers were most in between 20%-40%.3. In the process of monitoring, there were 5 times runoff during the wheat growing period, there were 4 times runoff during the rice growing period, and the whole year altogether has 9 times runoff. The runoff quantity of TN was more during the wheat growing period, of TP was more during the paddy rice growing period. In the glebe TN was washed away mainly in the form of NO3--N, and in the paddy field mainly in the form of NH4+-N. During the paddy rice growing period, nearly half of the runoff quantity of TP is in the form of DP.There was certain different runoff quantity of TN and TP between different processing. The rule of the runoff: In general, the strong rainfall result in big runoff; in the same rainfall, single runoff quantity is in inverse proportion to single rainfall duration, and is in direct proportion to field capacity. The runoff quantity of TN and TP has certain relations to the quantity fertilizer and the way of apply fertilizer.4. The result of runoff coefficient of N and P indicated: The runoff coefficient of TN is bigger during the wheat growing period; the runoff coefficient of TP is bigger during the paddy rice growing period. The whole year monitoring result showed that the runoff coefficient of TN is always bigger than TP. The runoff coefficient of TN is about 6%; the runoff coefficient of TP is about 0.4%. There was little different runoff coefficient of TN and TP between different processing, but the difference is not obvious.
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