| Wheat-Maize (W-M) rotation is one of the important crop-growing systems in Shanxi Province. It is mainly distributed in Linfen and Yuncheng Basin, and its production accounts for30%of the total production of cereal crops in the province. Unreasonable management of nutrients, especially excessive nitrogen application is a common problem in high-yield area of the region, not only reduces the efficiency of nutrient utilization, but also causes potential environmental problems. In this paper, Village-level household survey was conducted to understand the farmer's fertilization behavior and nutrient flows. Nutrient real-time monitoring technologies were applied in the experiments to establish the integrated nutrient management techniques (INM) of W-M rotation system in Shanxi Province. In addition, effects of nitrogen fertilizers on crop yield and environment was evaluated. Based on the above, using GIS technology, regional scale nutrient management system was established in Yongji County. The main findings are as follows:1. Nutrient flows and nutrient cycling studies showed that nutrient input and output was extremely unbalanced at the village level, specifically, nitrogen (N) and phosphorus (P) surplus, and the lack of potassium (K). It was due to the too much nitrogen inputs in W-M system. For example, the rate of N, P, and K inputs in Hongdong survey was714kg/ha.137kg/ha and42kg/ha, respectively.2. The field experiments results showed that INM could increase the crop yield and significantly reduce the amount of fertilizer, especially nitrogen fertilizer, compared with traditional fertilization management. In the3-year experiments, the total amount of nitrogen fertilizer using INM was862kg/ha, only35%of the traditional treatment. But the yield of INM was increased by6.2%, the annual profitabilty was increased by1262.4yuan/ha in Yongji trials, and3065yuan/ha in Hongdong trials. At the same time, the results about dynamic changes of soil nitrate nitrogen (NO3--N) concentration of0-120cm depth in Yongji County found that the application of INM could effectivly reduce the leaching of NO3--N, compared with the traditional treatment, due to the lower nitrogen rate. But whether the integrated nutrient management technology or farmer's traditional management, the leaching of NO3--N would occur after fertilization.3. Apparent N losses of INM in wheat season reduced by22%than traditional fertilization management in Hongdong and91%in maize season. In Yongji County, because INM increased the nitrogen rate, apparent N losses is higher64.7kg N/ha than traditional fertilization management in W-M rotation. For the nitrogen efficiency, partial factor productivity from applied nitrogen (PFPN) is increased by50%, compared with the traditional treatment.4. In2007-2008, the studies of the pathways of nitrogen loss were implemented in Yongji. The results showed that7%of the applied N was lost by ammonia (NH3) volatilization when the urea fertilizer was deep placed using farmers'local practice, and that1.2%of the applied N was lost as nitric oxide and nitrogen dioxide (NOX). The result of NOX loss is higher than the value of IPCC (1%), whereas, NH3loss was much lower than that observed in other experiments with deep placement in the North China Plain. The greater losses in those experiments may have been due to the higher rates of fertilizer application, which resulted in higher ammoniacal N concentrations.The study on nitrous oxide (N2O) emissions using chamber method showed that the amount of nitrous oxide (N2O) emissions increased with applying nitrogen fertilizer. In addition, soil temperature and humidity also affect N2O emissions. The nitrification inhibitor DMPP (3-4-dimethyl pyrazole phosphate) can effectively inhibit N2O emissions and reduce about half of the N2O emissions rate.5. Throngh the analysis of a total of511GPS-referenced soil samples taken in Yongji County, moderate spatial dependence was found for soil total nitrogen (TN), Olsen extractable phosphorus (OLSENP) and extractable potassiue (EXTK). but at different spatial scales. Low concentrations of TN and OLSENP were found and they are likely to be the main limiting nutrients for crop growth in this county. The spatial distributions of TN. OLSENP and EXTK were estimated by using kriging interpolation. The cropped areas of the county were divided into fertilizer management categories consisting of four classes of TN, three classes of OLSENP and two classes of EXTK. In3-year field verification trials in two villages, the crop yields of the wheat-maize rotation system increased by10-20%, and farmers'cash income increased by1550-2610RMB/ha/year where regional fertilization recommendations were implemented, in comparison with traditional farmers'practices.Given the above findings, the initial comments on the nutrient management of wheat-Maize rotation in Shanxi Province are as follow:1. In view of the nutrient imbalances of wheat-maize rotation system, the strategy which reduce nitrogen rate and stabilize phosphorus rate are adviced. In additon, it is necessary that strengthen stalk return to the field and apply organic fertilizer.2. Research of release nitrogen fertilizer matching the growth of wheat and maize is necessary when we study the nitrogen feitilizer application.3. Partial factor productivity from applied nitrogen of wheat and maize in Europe and America can achieve50-60kg/kg, but it has not yet reached this standard in our country. Therefore, the further increase of the yield is the current problem to be solved, the proposed nutrient management research with the combination of high-yield cultivation techniques.4. The regionalized fertilization maps are a practical alternative to site-specific soil nutrient management approaches in areas where it is not practical, because of small farm size or other constraints, to use intensive soil sampling and chemical analyses. Hence, a regionalized nutrient management (or nutrient zone management) system is more suitable for the rural Chinese situation and should be developed at the county, town or village levels.
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