Decomposition Rate Of Corn Straw Returning And Its Effects On Soil Nutrients

China is a big agricultural country,according to the end of 2016 the results of land survey shows that China's arable land area of about 20.3 million mu.In these agricultural arable land,each year will produce about 700 million tons of various types of crop stalks.While corn is one of the major food crops in the northeastern region of China.There are about 36 million tons of corn stalks produced in a province of Heilongjiang Province.Of these 36 million tons,nearly 40% of the straw is burned or discarded The way was wasted endlessly,but also reached the rate of 10%.Therefore,it is not only possible to prevent the further degradation of black soils in the northeastern black soil area,but also to reduce the energy wastage and environmental pollution caused by straw burning.Corn stalks after returning to field play an important role in increasing soil fertility,enriching soil nutrients and improving soil properties.In this paper,the changes of a series of nutrient indicators in the soil after straw returning to field can be explored for the production practice of straw returning to field.In this field,the field experiment was conducted to analyze the effects of the straw decay rate and the soil physical and chemical properties on the basis of the field experiment and the indoor culture.The field experiment was to analyze the effect of the corn stalk on the straw decay rate and the soil physical and chemical properties.The main conclusions drawn from the study on the respiration of soil,soil enzyme and microbial biomass carbon were as follows:The processing of straw through a year of field time,the decomposition rate of 57.9%-74.4%,of which the length of 3-5cm decay rate is higher than the length of 5-10 cm straw treatment;in the same field time,The same depth of burial,corn straw decomposition rate with the increase in nitrogen fertilizer increased;in the same field of time,the same nitrogen level,15 cm depth of straw decomposition rate of more than 30 cm depth Of the straw.And the higher the nitrogen level in the treatment,the faster the decay rate of corn stalks.Corn stalks into the soil,which can effectively reduce the soil bulk density,improve soil pore conditions.After returning to field,the reduction of soil bulk density was 2.24%-5.46%,the increase of porosity was 2.66%-6.06%.The same field length and the same straw length were15 cm,and the treatment depth was 30 cm group.The increase of soil total nitrogen was 1.71%-7.46%,the increase of soil total phosphorus was 2.1%-3.54%,and the soil was slow to increase the content of total nitrogen in the soil.Potassium increased by 3.8%-23.73%,organic matter increased by 0.67%-4.46%.The ratio ofcarbon to nitrogen was lower than that of CK,and the decrease of L3W2D2 treatment was the smallest,0.016;L1W1D1 decreased the maximum,0.38,and the difference was not significant The The change of soil alkali-hydrolyzable nitrogen was as follows: after the addition of straw was increased and then decreased,the maximum increase of alkali-hydrolyzable nitrogen in each treatment was L2W1D1,an increase of 28%,about 16.54 mg / kg,And with other treatment significant difference.The change of available phosphorus content in soils showed that the change of soil available phosphorus was gradually increased to the maximum value in the first 0-60 days,and the increase of soil available phosphorus was the highest after 150 days Treatment was L1W1D1,an increase of 14.7%,about 13.57 mg / kg,but with L2W1D1,L2W1D2 difference was not significant.The soil available potassium content increased significantly after 30 days in the field,and the partial treatment reached the maximum value during the period of returning to the field.After the subsequent 4 months of returning to the field,the soil was gradually reduced,and the maximum amount of soil available potassium was L2W1D2,An increase of 23.46%,about39.31 mg / kg.The activity of soil urease,soil sucrase and soil catalase can be improved by adding the nitrogen content of corn stover with nitrogen concentration in the soil.Under the same nitrogen application level,the soil microbial The amount of carbon and three kinds of enzyme activity will increase with the increase of the amount of straw.Under the same amount of straw,the treatment of C1N2 and C2N1 is the best.This method of returning to field showed some inhibition of soil polyphenol oxidase activity.The activity of soil polyphenol oxidase was significantly higher than that of other treatments in C0N0,which was not treated with straw and nitrogen fertilizer.Corn straw with a certain concentration of nitrogen can significantly increase the total soil respiration,which C1N0,C1N1,C2N1 treatment compared with the treatment of C0N0 compared to soil respiration increased by nearly 4 times.There was a significant positive correlation between soil microbial biomass carbon content,soil urease,sucrase activity and catalase activity and soil respiration.Soil polyphenol oxidase activity was negatively correlated with soil respiration.