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Research on Nitrogen Dynamic Balance and Optimum Management of Farmland

Author: LuXiaoZhe
Tutor: LiuYunLong
School: Shanghai Normal University
Course: Natural and geographical
Keywords: Rice Field surface water Soil Nitrogen balance Optimize the management
CLC: S511
Type: Master's thesis
Year: 2011
Downloads: 41
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Abstract

The face of the environmental problems caused by China's southern region of farmland the traditional fertilizer management mode, to study the development of scientific and effective water and fertilizer management measures to control agricultural non-point source pollution proposition is to improve the level of agricultural production and the protection of the ecological environment has important significance. How to reduce rice yield under the premise of using appropriate nitrogen fertilization techniques to develop a reasonable number of nitrogen applied nitrogen fertilizer and nitrogen fertilizer, to take reasonable irrigation and drainage measures to avoid excessive application of nitrogen fertilizer, reduce agricultural nonpoint source pollution the impact on the water environment, according to local conditions need further study. 2010 Agricultural Demonstration Zone in Yuyao, Zhejiang Sanqishi experimental field elements of different nitrogen levels on the field surface water and nitrogen dynamics change, the rice yield and yield, nitrogen use efficiency, Farmland nitrogen balance impact test. The purpose of this thesis is to provide technical indicators are based on rational fertilization, control nitrogen loss, protecting the ecological environment of water. The results of this study show that: (1) flooded paddy after applying urea, surface water nitrogen to ammonium nitrogen-based, low percentage of nitrate. Field surface water and total nitrogen and ammonium nitrogen reaches its maximum in the first days after fertilization, the impact of field ammonia volatilization, and then decreased gradually in a week or so to no N fertilizer district level. Influenced by nitrification, the field surface water nitrate peak time than ammonium nitrogen lag after fertilization on the third day to reach the maximum, then decreased gradually. Nitrate can be used as auxiliary indicators of urea in the rice fields of the widely applied ammonium nitrogen and total nitrogen as the paddy water pollution monitoring nitrogen indicators. Field surface water and nitrogen dynamics in nitrogen application after 7 days and three nitrogen concentration, and in surface water layer deeper, if there is heavy rain, it is prone to surface runoff, less than a week after fertilization to prevent nitrogen loss critical period , it is necessary to take measures to prevent nitrogen loss. Field surface water and nitrogen concentration and nitrogen rate extremely significant positive correlation graded nitrogen fertilizer is conducive to reduce or even solve nitrogen fertilizer loss of key measures to reduce the amount of farmland nitrogen loss from the source. (2) the field measured statistical data analysis results show that, within a certain range to increase the amount of nitrogen fertilizer can increase plant height, ear length and each ear total grains, promote tiller number, increase per acre panicles, but more than a certain fertilization causes rice blighted rate increase, seed setting rate and grain weight decreased. Studies have shown that nitrogen fertilization can increase rice yield increased within a certain range, but more nitrogen fertilizer would be counterproductive, leading to decline. Rice yield and nitrogen fertilizer can the quadratic trinomial function y =-0.03x2 11.63x 6168.29 fitted, a correlation coefficient of 0.9487. By calculation of fertilizer response function analysis, the amount of nitrogen obtained the highest yield corresponding 194 kg/hm2. In terms of the amount of the highest yield of this test fertilization, in the case of the affected rice production, less than farmers fertilization more than 10%. The principle of marginal benefit analysis of agricultural economics analysis the Zhedong Ningshao plains Yuyao optimum economic nitrogen rate, results showed that the nitrogen rate of 167 kg/hm2 the best economic benefits, the corresponding output of 7274 kg/hm2 . Below 167 kg/hm2, reduced fertilizer, fertilizer costs reduce, but fertilization reduce profits at a certain rate. Considered to reduce costs, improve efficiency and reduce the risk of nitrogen loss, the optimum amount of nitrogen in the study area for 167kg.hm 2. (3) the analysis of the results of the experimental field of Nitrogen utilization indicators: efficiency of fertilizer production Valley rice N uptake was highly significant negative correlation, the correlation coefficient of -0.997. Too much nitrogen uptake, fertilizer production Valley efficiency decline, production is not necessarily high, the prerequisite for the proper control of nitrogen uptake is to improve the efficiency of nitrogen fertilizer production Valley. Nitrogen fertilizer to decrease with the amount of nitrogen to improve absorption and utilization, changes in the range of 21.12% to 45.75%. Correlation analysis showed that nitrogen fertilizer absorption and utilization of nitrogen rate was a significant negative correlation, the correlation coefficient of -0.751, and crop N uptake was a significant positive correlation, the correlation coefficient was 0.914. Therefore, to improve the absorption and utilization of crops on nitrogen fertilizer, it is necessary to reduce the amount of nitrogen fertilizer. The nitrogen partial factor productivity is also reduced with the increase of the amount of nitrogen, changes in the range of 35.33 to 50.76 kg.kg-1. The nitrogen partial factor productivity fertilization a highly significant negative correlation, the correlation coefficient of -0.975. Nitrogen physiological efficiency with increasing nitrogen rate increased from 17.46 kg.kg-1 to 42.36 kg.kg-1, but more than 195 kg/hm2 after fertilization level dropped to 20.51 kg.kg-1. Correlation analysis showed that nitrogen physiological efficiency and crop N uptake showed a significant negative correlation, the correlation coefficient of -0.897, and crop yields were highly significant positive correlation, the correlation coefficient was 0.699. Nitrogen agronomic efficiency handled by different fertilizer levels are very low, in the range of 5.3 ~ 8.2 kg.kg-1 changes, which may be too high and the soil background nitrogen. (4) monitoring of soil, rice and irrigation water, calculated under different fertilization treatments nitrogen balance of the soil - crop system. Analysis of nitrogen balance of each treatment, soil residual nitrogen than plots with no fertilizer residues, improve as the amount of nitrogen and residual nitrogen in the soil also presents the trend of continued growth. Nitrogen surplus not absorbed by crops and residues in the soil and in the loss of two parts nitrogen and environment with increasing nitrogen rate, nitrogen surplus increased significantly, and the apparent surplus of small nitrogen fertilization treatments higher than N treatment. Therefore, in order to reduce nitrogen apparent residual loss, taking into account soil nitrogen supply capacity, it is essential to reduce the nitrogen rate.

Research on Nitrogen Dynamic Balance and Optimum Management of Farmland

Abstract

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