Effects Of Different Nitrogen Application And Mulching On Maize Growth And Soil Quality In Northern Shaanxi Province

In the study of agriculture in northern Shaanxi,the most important factors limiting the development of agriculture are water scarcity and soil erosion,and soil fertility is also an important factor limiting the development of agriculture in northern Shaanxi.The study of the effects of soil moisture and nutrients on crop yield and soil quality is an effective way for sustainable agricultural development and a fundamental measure for food security and environmental protection.This paper investigates the effects of mulching and different N application on the growth,yield and soil fertility of maize in northern Shaanxi,with a view to providing a theoretical basis and technical support for agricultural field management techniques.A randomised group experimental design was used in this study.11 treatments were set up with two factors:planting pattern（M0）and mulching（M1）,and N application rates of 80（N1）,120（N2）,160（N3）,200（N4）and 240（N5）kg·hm^-2 respectively.The treatment without N application was used as a control（CK）.The main findings were as follows:（1）The individual factors of mulching and N application had significant or highly significant effects on plant height,stalk thickness and leaf area index of field maize,and the interaction effect of the two had highly significant effects on plant height.As fertility progressed,plant dry matter accumulation gradually increased,and both mulching and N application significantly affected dry matter accumulation.At the nodulation stage,mulching accelerated the growth and development of the plants,and the dry matter accumulation of maize at different N application rates reached the peak first than without mulching;at the spatulation stage,the dry matter accumulation of the plants showed a trend of increasing and then decreasing with the increase of N application;at the maturity stage,the dry matter accumulation of the plants leveled off.（2）Mulching significantly increased nitrogen accumulation in maize at the nodulation stage,and nitrogen accumulation in all nutrient organs showed a trend of increasing and then decreasing with increasing nitrogen application;nitrogen transport in maize nutrient organs showed a trend of decreasing and then increasing,and nitrogen application and mulching significantly affected nitrogen transport efficiency in maize,and nitrogen uptake efficiency showed a significant decreasing trend.Nitrogen application significantly affected N fertilizer utilization rate,N fertilizer bias productivity,N fertilizer agronomic utilization rate and N fertilizer yield contribution rate,while mulching significantly increased N fertilizer bias productivity,N fertilizer agronomic utilization rate and N fertilizer yield contribution rate,and the reciprocal effect of N application and mulching was only reflected in the effect on yield contribution rate.（3）Mulching increased corn yield by 4.78%to 18.17%compared to corn without mulching,nitrogen application increased corn yield by 2.00%to 40.61%,while mulching with nitrogen application increased corn yield by 32.72%to 54.62%.Mulching and N application had highly significant effects on maize yield,with mulching significantly increasing maize yield and showing a trend of increasing followed by decreasing maize yield with increasing N application;the highest maize yield in the field was achieved at160 and 120 kg-hm-2 level of N application under open field and mulching,respectively.Maize seed quality was significantly and positively correlated with plant nitrogen accumulation,with correlation coefficients ranging from 0.52 to 0.78;mulching significantly increased starch content and soluble sugar content by 8.72%to 24.44%and6.80 to 73.28%,respectively.（4）Soil nutrients in the 0～60 cm soil layer showed a decreasing trend with increasing depth,and soil nutrients differed significantly among treatments in the horizontal direction.Increased application of nitrogen fertilizer reduced soil enzyme activity,and mulching did not have a significant effect on enzyme activity.The effect of alkaline nitrogen on soil sucrase,urease and phosphatase activity was positive and negative for alkaline phosphatase activity at the nodulation stage,while the effect of water content on enzyme activity was the opposite;the effect of alkaline nitrogen and organic matter content on soil sucrase,urease and phosphatase activity at the spatulation stage was positive and negative for alkaline phosphatase activity;the effect of alkaline nitrogen content on enzyme activity at the maturity stage was positive,and the effect of ammonium nitrogen on enzyme activity at the maturity stage was positive.The effect of ammonium nitrogen content on sucrase,urease and phosphatase was positive.（5）The main soil factors affecting maize yield were water content,alkaline nitrogen,fast-acting phosphorus,fast-acting potassium,organic matter,sucrase and phosphatase;the soil factors affecting quality were water content,nitrate nitrogen,ammonium nitrogen,alkaline nitrogen,organic matter,urease,catalase and phosphatase.In summary,in order to achieve higher N fertilizer utilization efficiency and N fertilizer yield contribution,N fertilizer application should be reduced under the premise of high and stable yield;through redundancy analysis,it is concluded that soil alkaline nitrogen content has the greatest effect on enzyme activity;soil factors in northern Shaanxi have important effects on maize yield and quality,and the soil factors that have the greatest effect on maize yield are alkaline nitrogen and sucrase activity,and those that have the greatest effect on starch content are The most influential soil factor on maize yield is alkaline nitrogen and sucrose enzyme activity,the most influential on starch content is nitrate nitrogen,the most influential on reducing sugar content is urease activity,and the most influential on soluble sugar content is organic matter content.Under the premise of promoting crop growth,improving yield,quality and N fertilizer utilization efficiency,the optimal planting pattern for maize cultivation in northern Shaanxi was 200 kg·hm^-2 of N application under transparent plastic...