| In recent years,the large-scale increase of Maize Yield in the Loess Plateau mostly depends on the input of high fertilizer and plastic film mulching,resulting in the increase of nitrogen residues in soil layers,resulting in environmental pollution.Optimizing cultivation patterns can improve soil moisture and nutrient status,which has attracted wide attention.However,the contribution of optimized cultivation patterns to yield,the effects of soil moisture and nutrients on soil profile and the comprehensive effects of environment are still unclear.In order to explore the high-yield and high-efficiency cultivation pattern of maize and its environmental effects in the Loess Plateau,three cultivation patterns,namely,traditional cultivation pattern?T1?,Super-high-yield cultivation pattern?T2?and high-yield and high-efficiency cultivation pattern?T3?,and organic fertilizer with density treatment,were set up in this study.The population growth,soil moisture,yield of spring maize,the change of water use efficiency and nitrogen use efficiency,ammonium nitrate accumulation and its profile distribution under different cultivation patterns were studied through a two-year field experiment.The main conclusions are as follows:1.Different cultivation patterns,combined application of organic fertilizer with density change will affect the growth of maize.The combination of organic fertilizer increased the leaf area,promoted the growth of maize,and laid a physiological foundation for dry matter accumulation after anthesis.The combination of inorganic fertilizer and organic fertilizer promoted the dry matter transport of stems and leaves,increased the dry matter accumulation of shoots before and after anthesis,especially helped to increase the number of grains per spike and 1000-grain weight,thus maintaining high and stable yield.Compared with the traditional cultivation,the yield of Super-high-yield cultivation,high-yield and high-efficiency cultivation increased by 4420 kg·hm-22 and 4157kg·hm-2,respectively.2.Cultivations significantly affected water and nitrogen use efficiency.The combination of organic fertilizers can increase soil water capacity,alleviate soil drying caused by high yield and high density,increase soil water content in tillage layer?0-60 cm?,effectively utilize soil water in middle layer?60-120 cm?,and maintain the stability of soil water in deep layer?120-200 cm?.The water use efficiency of the two optimized cultivations increased by 58.9%and 40.4%respectively.Rational combination of organic fertilizer and density significantly increased the utilization rate of nitrogen fertilizer,promoted the utilization of inorganic nitrogen fertilizer,and then increased the efficiency of nitrogen transport to grains.3.Rational combination of organic fertilizer and density slowed down nitrate nitrogen leaching to the deeper layer of soil.Fertilizer application in super-high yield cultivation exceeded crop absorption and utilization.Nitrate accumulation reached 68.03 kg·hm-2 in the 60-100 cm soil layer in the wet year,50.91 kg·hm-2 in high-yield and high-efficiency years,and only 5.81 kg·hm-2 in 80-100 cm soil layers.High yield and high efficiency pattern?T3?can ensure high yield,high water use efficiency and less nitrate leaching,which is the best cultivation pattern in this experiment.In general,when combing organic fertilizer and planting density,the yield and water use efficiency have the potential to increase sustainably,and reduce the pollution to the soil environment,which provided a theoretical and practical basis for the optimization of cultivation pattern in the Loess Plateau.Optimized fertilizer management combined with organic fertilizer and higher planting density can alleviate the side effects of high density and fertilizer application on soil water and fertilizer environment,improve water and nitrogen utilization efficiency,and thus increase yield. |
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