| Straw is a kind of renewable resource,which contains abundant nutrients such as C,N,P and K.A reasonable return of straw can improve soil structure and increase soil fertility.Domestic and foreign scholars have done a lot of work in the field of straw returning to the field and have obtained rich scientific research results.Under the background of modern agricultural production in Heilongjiang Province,how to avoid the environmental pollution caused by the waste of straw resources and improve the soil fertility by returning straw to the field has become the focus of the government and research workers.How to control the straw returning depth,straw buried depth and other factors within a certain range when straw is returned to the farm can not only reduce the energy consumption of agricultural machinery and equipment operation,but also not affect the decomposition of straw and soil fertility after returning to the north.There are few reports on this aspect under the conditions of agricultural machinery operation.This study focuses on the straw returning length,straw returning amount and straw buried depth to study the characteristics of straw decomposition,nutrient release,and the functional diversity of microbial communities associated with decomposition.Under the condition,the straw-returning method of increasing straw efficiency will provide a theoretical basis for the reasonable return of straw.This research concluded the following results:(1)During the two-year straw return period,the straw decomposing rate is consistent with the total organic carbon(TOC),total nitrogen(TN),and total phosphorus(TP)total potassium(TK)release trends of the straw.Slow late.With the increase of straw length and burial depth,they gradually decreased,but with the increase of straw returning amount,the performance increased first and then decreased.When the straw returning amount was 4800 kg/hm2,the straw decomposition rate was the highest.73.32%,straw TOC,TN,TP,TK release rate also reached the maximum,respectively: 75.89%,74.38%,78.64%,93.45%.(2)With the increase of straw length and burial depth,the carbon source metabolic activity(AWCD value),richness index(H),dominance index(D),and evenness index(E)of the microbial community of straw rot decomposition gradually The trend of decreasing,with the increase of straw returning amount,showed the trend of increasing first and then decreasing.When straw returning amount was 4800 kg/hm2,it had the greatest impact on the functional diversity of the microbial communities that promoted straw decomposition.(3)The interaction of straw length,returning amount,and burial depth with single factor and three factors indicated that when the length of straw is 15 cm,the amount of straw is 4800 kg/hm2,straw burial depth is 5 cm,straw decomposition The rate,nutrient release rate,AWCD value of straw decomposing microorganisms,H,D,and E all reached the highest,and the soil bulk density was the lowest and the porosity was the highest.(4)Based on game theory comprehensive weighting method,the order of weight of straw single decomposition effect evaluation index is: straw decomposition rate> AWCD value> H> TOC> TN> D = E> TP> TK,which influences straw comprehensive decomposition.The main effects of the experimental factors of the effect are as follows: straw quantity> straw depth> straw length.There was a negative interaction between the straw length and the amount of straw,the depth of straw and the amount of straw,and there was a positive interaction between the length of straw and the depth of straw.Through the establishment of model and response surface optimization analysis,the best way to promote straw decomposition is: straw length 5-10 cm,straw volume 4400-5920 kg/hm2,straw depth 6-11 cm. |
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