Effects Of Nitrogen Fertilizer Management Methods On Yield And Nitrogen Use Efficiency Between Wheat In Dryland And Rice Stubble Wheat In Jianghan Plain

The Jianghan Plain is an important part of the wheat region in the middle and lower reaches of the Yangtze river.Improving the yield of wheat and ensuring the sustainable development of agriculture are the basis of current development.Nitrogen fertilizer regulation is the main factor affecting wheat yield and ecological environment.To study the response of the yield,growth and nitrogen utilization of wheat in dryland and rice stubble wheat of Jianghan Plain to the operation mode of nitrogen fertilizer,and to reduce the residual and loss of nitrogen on the basis of ensuring the wheat yield,so as to provide a theoretical basis for formulating reasonable management measures of nitrogen fertilizer and reducing environmental pollution.This study in Jianghan plain wheat in dryland and rice stubble wheat field experiment was carried out under two kinds of wheat planting patterns,set up five different nitrogen fertilizer management patterns,with no fertilizer treatment as control,the system analyzes the wheat in dryland and rice stubble wheat yield and yield components,laws of growth and nitrogen uptake,soil nitrate nitrogen residue,etc.To explore the possible ways to realize wheat yield increase and ensure the sustainable development of agriculture by the combination of different wheat planting modes and nitrogen fertilizer operation modes.The main research results are as follows:1. In the traditional nitrogen fertilizer model,attention was paid to the treatment of topdressing in the early stage,and the yield of wheat in dryland was higher,13%?27%higher than that of rice stubble wheat.After the nitrogen fertilizer treatment was optimized,there was no significant difference in the yield of the two stubble wheat,and the grain yield of both wheat in dryland and rice stubble wheat was the highest treated with M5(one third of N was applied at sowing,wintering and jointing,respectively),with the grain yield up to 6418,6559 kg/hm~2.In terms of yield composition,the number of ears of wheat in dryland was significantly higher than that of rice stubble wheat by5%?39%,and that of rice stubble wheat treated with nitrogen fertilizer after the shift was significantly higher than that of wheat in dryland by 2.9%?5.4%,and the 1000-grain weight was slightly higher than that of rice stubble wheat.2. Under the same nitrogen fertilizer operation mode,the maximum number of tillers in upland wheat was higher than that of rice stubble wheat in winter,while the maximum number of tillers in spring was smaller than that of rice stubble wheat,and the tassel rate of upland wheat was 4%?25%higher than that of rice stubble wheat.Optimized fertilization could significantly improve the tassel rate of rice stubble wheat.From flowering stage to maturity stage,the leaf area index was higher wheat in dryland,and the decline rate was 19%lower than that of rice stubble wheat.On the whole,the dry matter accumulation of the population in each growth period was higher than that of rice stubble wheat,and the wheat in dryland in the maturity period was 1533?3903 kg/hm~2higher than that of rice stubble wheat,with the highest M5 treatment.The variation trends of"slow-fast-medium"(DW)and"medium-fast-slow"(RW)were different in grain filling.3. The total nitrogen accumulation in upland wheat at flowering stage and maturity stage was significantly higher than that of rice stubble wheat,31%and 46%higher than that of rice stubble wheat,and 34%higher than that of rice stubble wheat on average.The nitrogen transfer efficiency and contribution rate of upland wheat were 11.7%and 15.5%higher than that of upland wheat respectively.The nitrogen accumulation of the vegetative organs in the flowering and maturing stages of wheat was higher with M5 treatment,and the transfer efficiency and contribution rate of the post-flowering vegetative organs had no significant advantage compared with other treatments.4. We select the most productive two nitrogen treatment(M4:recommended:jointing stage fertilizer=5:5,M5)after wheat harvest 0-200 cm soil nitrate nitrogen content analysis,the dry land wheat and rice stubble wheat 0-200 cm soil profile nitrate content nitrogen"table gathered phenomenon",the dry land wheat 0?20 cm soil nitrate nitrogen content is 1.5?2.5 times that of rice crop of wheat,rice stubble wheat nitrate accumulation peak in deep soil layer on the dry land wheat.Nitrate accumulation in the0-200cm soil layer of upland wheat can reach 63.1-73.8kg/hm~2,which is 10.5%?26.6%higher than that of rice stubble wheat.5. In this experiment,the apparent nitrogen utilization rate of wheat can reach 61.1% to 72.7%,and the apparent nitrogen residual rate of dry wheat is significantly higher than that of rice stubble wheat by 16%and 21.2%,while the apparent nitrogen loss rate of rice stubble wheat is higher.The apparent nitrogen utilization rate of upland wheat M5treatment increased by 11.6%compared with that of M4 treatment,and the apparent nitrogen residual rate and loss rate decreased by 5.9%and 5.7%respectively.The apparent nitrogen utilization rate,residual rate and loss rate of rice stubble wheat M5treatment were increased,but not significantly.According to different wheat planting systems,the determination of appropriate nitrogen fertilizer operation mode is conducive to improving wheat yield,nitrogen absorption and utilization,and relieving environmental pressure.Under the model of upland wheat and rice stubble wheat in Jianghan Plain,the treatment with total nitrogen application amount of 180kg/hm~2 and three times of nitrogen application promoted the uptake of nitrogen by the plants and reduced the nitrate nitrogen residue in the soil,which was the best treatment for both yield and fertilization benefits in Jianghan Plain.