| Crop straw is a kind of precious natural resources, returning straw into soil is an important way of utilization of straw. Verify rice straw returning on the following winter wheat yield and nitrogen utilization influence to improve wheat yield, benefit and protect environment has important significance. Field experiments were conducted in Yangzhou and Lian Yungang during2009-2011to explore the effect of straw returning, nitrogen rate, ratio of basal to topdressing and seeding rate on soil physics and chemistry character, grain yield and nitrogen utilization efficiency. The main results were as follows:1. Returning straw into soil may reduce the soil moisture content, to enhance the soil temperature of the10cm soil layer, to reduce the soil pH value, to reduce the0-20cm soil bulk specific gravity. Along with the nitrogenous fertilizer amount used enlargement, the soil organic matter content reduces, the straw stalk may obviously raise the Yizheng area soil organic matter content.2. Nitrogen fertilizer application increased nitrate nitrogen (NO3-N) and ammonium nitrogen (NH4+-N)0-40cm soil layer; soil inorganic nitrogen content increased with increasing of basal nitrogen rate before jointing and soil inorganic nitrogen content increased with increasing of topdressing rate after jointing stage. Under same the nitrogen, the straw stalk is also influence to the soil inorganic nitrogen content, returning straw stalk to the soil reduced the0-40cm soil layer NO3-N and NH4+-N content of the sown seeds to the jointing stage, but enhanced the0-40cm soil layer NO3-N and NH4+-N content after jointing stage.3. Apparent N surplus (ANS) and deficit were different at different growth stages among treatments, nitrogen deficit occurred throughout wheat growth season in soil without N fertilizer application. During the whole growth season, ANS increased with increasing of nitrogen rate and basal ratio, increases along with the seeding rate reduces. Nitrogen surplus before jointing was the major nitrogen surplus and the straw returning may reduce ANS from sowing to jointing stage.4. Returning straw to soil cut winter wheat’s rate of seedlings emergence, the stem tiller number, the community to do the material accumulation quantity, the straw returning also raised the chlorophyll content of winter wheat flag leaf after anthesis, enhanced the flag leaf photosynthesis speed and the fluorescence parameter in the watery metaphase and late stage. Straw returning mostly reduced the winter wheat yield in two places, the suitable nitrogenous fertilizer application and the enhancement seeding rate may reduce the influence of the grain yield under returning straw to soil.5. Nitrogen applications and seeding rates affected nitrogen accumulation significantly. Increases nitrogen rates to be advantageous in enhancing nitrogen accumulation, but also cut the nitrogen use efficiency. The suitable basal-topdressing ratios and seeding rates may reduce the soil ANS, increases the nitrogen use efficiency. The straw returning enhances NUE, NFAE and NFUE of the wheat in Yizheng area, but the Lianyungang area NFAE and NFUE dropped because influence of the winter wheat growth. T2treatment indicated NUE and NFAE are highest under straw returning condition in the two areas, but the Lianyungang area issues high in the T3treatment, increases the sowing seeds rate to be possible to raise NFAE and NFUE of the winter.In conclusion, under this test condition, it had advantage to improve winter wheat growth, reduce loss of NO3-N leaching, increase nitrogen uptake and allocation, remobilization to grain, decrease loss of fertilizer N, and then enhance yield and nitrogen utilization efficiency when nitrogen rate was270kg.hm-2and topdressing ratio was increased to60%and seeding rate were increased to150Kg.hm-2appropriately in Yizheng, and270kg.hm"2and topdressing ratio was increased to70%and seeding rate were increased to180Kg.hm-2appropriately in Lianyungang. |
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