Research On Nitrogen And Phosphorus Loss In Wheat-Rice Rotation In Chao Lake Basin Under Different Fertilization

Agriculture is the foundation of the national economy. In recent years, with the development of China’s agriculture, agricultural fertilizer showed rapid growth, resulting in excessive fertilization or rich fertilizer utilization rate of fertilizer, manure and fertilizer residue loss, ultimately resulting in eutrophication. As one of China’s five largest freshwater lakes, Chaohu not spared. Nitrogen and phosphorus loss brings to eutrophication and other pollution problems getting highlights, has attracted the attention and concern of the community. Study the characteristics and rules of nutrient loss during rice-wheat rotation under different fertilization had a great significance influence on changing the unreasonable mode of production in the process of agricultural production, reducing environmental pollution, finding out the pollution base, developing agricultural industry of Chaohu area reduction ring corresponding technology and so on.The study used the method of field monitoring in situation during zhonghan town juchao district, chaohu city. Study the nitrogen and phosphorus loss, the loss coefficient and the utilization rate of fertilizer and other effects in the conventional fertilization, high yielding, high yielding+reduction 30% in nitrogen, high yielding+ +reduction 50% in phosphorus and straw treatments. The results that got from the monitoring test are summarized as follows:1、The annual runoff was 6to7 times per year during rice-wheat rotation in chao lake basin and the runoff coefficient about 20% average annual, the rice season was the main production flow period during this study two years.2、During different fertilizer treatments, the total nitrogen losses was 2.09-2.09 kg/hm2and the total phosphorus losses was 0.033-0.076 kg/hm2in wheat season. While the rice season the total nitrogen losses was3.49-22.67 kg/hm2, the total phosphorus losses was 0.099-0.692 kg/hm2.Season of The nitrogen and phosphorus losses in rice season is greater than the wheat seasons, so the rice season is the main period of nitrogen and phosphorus loss. Different fertilizer treatments, the reduction of nitrogen fertilizer treatments effectively reduce the loss of total nitrogen, phosphorus reduction process of effective to reduce the phosphorus loss. Compared with conventional fertilization, straw returned can reduce the loss of nitrogen and phosphorus in a certain extent, but not stable.3、The coefficients of nitrogen and phosphorus loss in the rice season is greater than the wheat season and influenced by the runoff, the change is clear between the different fertilizer treatments. The coefficient of nitrogen loss was 0.21-4.52%and the total phosphorus is 0.018-0.333%. In different treatment, the conventional while the high yield fertilization’s total phosphorus coefficient is the largest.4、Under rice-wheat rotation, two years different fertilizer treatments on wheat and rice of nitrogen and phosphorus uptake is different, the specific performance in 2011 total nitrogen for wheat:high yield fertilization> conventional fertilization> straw returned> high yield+reduce 50% of phosphorus> high yield+reduce 30% of nitrogen> blank; In 2012, total nitrogen is shown as:high yield fertilization> straw returned> high yield+reduce of 50% phosphorus> high yield+reduction 30% of nitrogen> conventional fertilization> blank. Conventional fertilization of wheat grain is about 100 kg/hm2, the total nitrogen uptake of phosphorus uptake is about 20 kg/hm2, the rice grain total nitrogen uptake of 40-60 kg/hm2, total phosphorus uptake of about 20 kg/hm2, nitrogen uptake changes significantly, the uptake of phosphorus is relatively stable.5、The nitrogen and phosphorus fertilizer use efficiency, crop yield, nitrogen and phosphorus uptake has a direct relationship. The nitrogen utilization rate in wheat season is higher than rice season, nitrogen utilization efficiency between different fertilizer treatments on is 25.19to 65%, the utilization efficiency changed between two years is large. The straw returned nitrogen fertilizer utilization rate is higher than other treatments. Different fertilizer treatments phosphate fertilizer utilization rate fluctuations between 12.29-33.27%, reducing phosphorus utilization rate of nitrogen fertilizer treatments.6、No fertilization and reduce fertilization will affect crop yields, especially no fertilization which the influence of the formation of very significant production during two consecutive years the output of rice and wheat. In addition to the blank fertilizer treatments, the average production of wheat in different fertilizer treatments was 6361.4 kg/hm2, production overall performance is:the high yield fertilizer> straw returned>high yield+reduce30% of nitrogen> high yield>high yield+reduce 50% of phosphorus> conventional blank; while the rice average production is 7674.8 kg/hm2, high yield fertilization> straw returned> high yield +reduce 50% of phosphorus> conventional> high yield+reduce 30% of nitrogen>blank. The total output of rice and wheat rotation for two years performed as high yield fertilizer Conventional>high yield+reduce 50% of phosphorus>straw returned>high yield+reduce30% of nitrogen> blank; while year 2012 performed as high yield fertilizer>straw returned>high yield+reduce 50% of phosphorus>high yield+reduce30% of nitrogen>conventional> blank.