Spring Maize Under Different Soil Fertilities Nitrogen Optimization Technology

Nitrogen (N) is one of the most limiting nutrients for maize production. It is necessary to research on crop yield under different levels of soil nitrogen supply, monitor plant N uptake and soil N supply to ensure an adequate N supply for spring maize, growth, improve N use efficiency and reduce N losses. There are a lot of research which is limited by region about maize nitrogen regulation and nitrogen recommendation on different areas. However, little work has been done in relation to maize nitrogen regulation response to different soil fertilities in Shanxi province. Therefore, three field trials combined with plant analysis and soil determination were carried out to investigate spring maize response to different N application rates. In order to get an appropriate nitrogen application rates for N management in spring maize. The three experimental sites included Dongyang as representative of the soils with low fertility, Qixian as representative of the soils with medium fertility and Wenshui as representative of the soils with high fertility. The main results were researched as following:Different nitrogen application rates had little impact on the dynamic changes of total biomass of spring maize under different soil fertilities, just changed the different growth stages of total biomass. From flare-opening to maturity, the biomass accounted for more than half of the total biomass. Yield effects were fitted with a linear plus plateau model under different nitrogen application rates. The three optimum nitrogen application rates were227,204,201kg/hm2for Dongyang, Qixian and Wenshui respectively. The yield would not increase when N application rate increased to a certain value.Maize nitrogen content under different soil fertilities tended increased during early-middle growing season, and then decreased in the late growing season for each N supplying treatment. In general, different nitrogen application rates had little impact on the nitrogen content. Nitrogen accumulation and biomass trends were almost identical, presenting S type curve with different nitrogen application rates. Before silking, nitrogen accumulation in different treatments was insignificant, while from silking to maturity the nitrogen supplying treatments were significantly higher than not supplying treatments.After the maize harvested, the residual nitrate nitrogen in0～200cm soil profile of nitrogen supplying treatments increased significantly. If nitrogen application rates were higher than270kg/hm2for Dongyang,180kg/hm2for Qixian and Wenshui, the nitrate N accumulation in0～90cm soil profile was excessive. With the increased of N application rates the apparent N loss increased linearly, the loss of the N540treatment was the most at three field trials. During the maize growing season, to keep suitable nitrogen and lower loss of apparent N, the nitrogen application rates should were270kg/hm2for Dongyang,180kg/hm2for Qixian and Wenshui. In summary, considering spring maize yield, nitrogen use efficiency and environmental protection, the appropriate N application rates should be maintained at225kg/hm2for Dongyang,200kg/hm2for Qixian and Wenshui.