The Effect Of Increasing Nitrogen On Soil Nutrient,Biological Index And Yield Under The Condition Of Straw Returning

In order to determine the effect of nitrogen on the straw decomposition under the condition of rotary tillage,the test design of the location crack area was adopted,and the main area was returned to the field(with7500kg·hm^-2 straw mulching and non-return treatment),and the subregion was treated with nitrogenation(0,60,120,180,240 kg·hm^-2).Respectively in 2016,corn planting beginning after jointing stage,tasseling stage,mid milk ripe,full ripeness period 0-15 cm soil samples,determination of microorganism quantity,enzyme activity,alkali solution nitrogen,available phosphorus and available potassium and organic matter content,corn harvest yield when mature;In 2017,when the corn is mature,the soil samples of 0-15cm will be collected to determine the nitrogen,quick effect phosphorus,instant potassium,organic matter,and harvest measurement.1.The soil physical properties were affected by the increase of nitrogen in straw mulching.Whether or not it is suitable for increasing nitrogen,it decreases the bulk density,increases the total porosity,and increases the nitrogen content of the minimum bulk density and the maximum total porosity in the field and the field,respectively,120kg·hm^-2 and 180kg·hm^-2.Increasing nitrogen to the capillary porosity,180kg·hm^-2and240kg·hm^-2.2.The straw returned to the field to increase the nitrogen.In the early stage,the number of fungi and bacteria in the soil was the most,and the latter was rapidly decreased,while the actinomyces decreased after the first increase.Among them,the early stage fungi and bacteria increased with the increase of nitrogen fertilizer,and the actinomycetes were the most when the nitrogen fertilizer was 120kg·hm^-2 to180kg·hm^-2.There is a positive correlation between fungi and actinomyces.3.The changes of urease activity in different nitrogen treatment were small.The activity of sucrase,cellulase and phosphatase increased with the increase of nitrogen,and the activity was highest in 180kg·hm^-2.4.Adding nitrogen affects soil nutrients.In soil,the content of nitrogen and available phosphorus decreased with the increase of the number of days.The maximum amount of nitrification was obtained by using nitrogen in 0-60kg·hm^-2,60kg·hm^-2 increased nitrogen consumption and consumed most phosphorus.The content of available potassium in soil decreased first and then increased.The increase of nitrogen in120kg·hm^-2 soil increased the content of available potassium.5.There was positive correlation between soil microorganism and quick-acting nutrients under different nitrogen treatments.There was a correlation between the soil enzyme activity of different nitrogen treatments and the content of the available nutrients,and the contents of urease and quick-acting nutrients in soil were negatively correlated.There was a positive correlation between sucrose enzyme and available nutrient content in soil.6.In the first year,the field of straw is increased by 24.89%compared to the non-return field,and the yield of nitrogen increased by 60kg·hm^-2 is the highest among the stragm,and the yield is 120kg·hm^-2.In the second year,the average yield of straw was only 2.68%,and the difference was not significant.