Effects Of Straw Mulching Less Tillage And Slow Mixed Fertilization On Nitrogen Efficiency Of Dryland Maize

In order to solve the problems of low soil temperature,poor seedling emergence,weak seedling growth,and difficult operation of nitrogen topdressing caused by straw mulching in dryland areas of Inner Mongolia,this study combined controlled release urea with improved straw mulching and less tillage to explore a simplified nutrient management approach suitable for straw mulching and less tillage.Two experiments were set up.In experiment 1:four straw mulching and minimum tillage modes were set under the conventional fertilization mode,including conventional ridge cropping（CP）,no-tillage in field（NT）,no-tillage in mulch（RNT）and mulch strip tillage（RST）.In experiment 2,four nutrient management modes were set under straw mulched strip tillage（RST）mode,including conventional fertilization（Sd）,fertilizer-free zone（0N）,30%slow mixing（30%Cr）and 50%slow mixing（50%Cr）.By monitoring the process of maize growth and development,plant nitrogen accumulation and distribution and soil nitrogen changes,the relationship between maize nutrient absorption and soil nitrogen supply was coordinated to meet the nitrogen demand of maize throughout the growth period.The main results were as follows:（1）RST is suitable for increasing yield and increasing efficiency of straw mulching and less tillage in dry farming areas of Inner Mongolia.Compared with CP treatment,RST treatment significantly increased dry matter accumulation by 9.6%,dry matter transport by50.1%and ears number by 9.6%,resulting in a 5.1%increase in yield.The nitrogen uptake,nitrogen transport,and nitrogen fertilizer uptake efficiency were increased by 2.7%,65.7%,and 7.5%,respectively.The nitrogen fertilizer physiological use efficiency and nitrogen fertilizer use efficiency were increased by 48.5%and 26.3%,respectively,increased the fertilization income by 981.8 CNY·hm^-2,decreased the inorganic nitrogen residue at the mature stage by 6.3 kg·hm^-2,and the nitrogen surplus by 10.6 kg·hm^-2.（2）Under straw mulching,50%Cr is suitable for one-time slow-mixing fertilization mode in dry farming areas of Inner Mongolia.Compared with the Sd treatment,50%Cr increased the dry matter transport amount,the number of grains per ear and the 1000-kernel weight by 64.3%,2.4%and 6.7%,respectively,resulting in an increase of 7.3%in yield.The nitrogen uptake and nitrogen fertilizer uptake efficiency were increased by 3.3%and 8.7%,respectively.The nitrogen internal efficiency and nitrogen use efficiency were increased by50.5%and 62.6%,respectively,and the fertilization income increased by 2956.1 CNY·hm^-2.The residual inorganic nitrogen,the apparent loss of soil nitrogen,and the nitrogen surplus at maturity decreased by 8.2 kg·hm^-2,7.4 kg·hm^-2,and 15.6 kg·hm^-2,respectively.The 50%Cr treatment satisfied the crop well.The needs of the entire growth period,and maximize the nitrogen use efficiency.To sum up,in the dry area of Inner Mongolia,under article straw mulching cultivation,50%slow mixing fertilizer although increased the cost,saves labor costs but one-time basal dressing with mechanical fuel costs,reduce the mechanical into number,cooperate to increase production efficiency,eventually farmers fertilizer yields increased significantly,and reducing fertilizer negative contribution to the environment,It can be used as a practical technical mode of straw mulching with less tillage and slow mixing fertilizer to solve the problem of weak growth of maize seedlings and difficult nitrogen topdressing under the condition of straw mulching in Inner Mongolia dryland.