| In order to solve the problems of soil becoming barren,plough layer becoming shallow,soil structure and function being out of harmony,soil fertility generally being low and crop yield being low in south Liaoning province,this paper carried out a field plot experiment to study the effects of returning modes and straw-decomposing inoculant on the decomposition characteristics of maize straw.The split zone design was adopted in the experiment.The main zone: No tillage straw mulching returning to the field(N),deep loose straw turning over to bury returning to the field(P)and rotary tillage straw turning over to bury returning to the field(R);Sub-area: Straw-decomposing inoculant treatment(Tr),set to add straw-decomposing inoculant(T+S)and no straw-decomposing inoculant(T).There are 6 treatments.Through a nylon mesh bags straw decomposing and simulation experiment and field experiment,the method of the combination of the decomposition characteristics of straw components,regularity of nutrient release,various forms of soil organic carbon and soil nutrient,in order to clarify the characteristics of straw decomposition,nutrient release and its influencing factors under different returning modes,and to explore an effective returning mode suitable for soil fertilization and corn production in maize producing areas in southern Liaoning,so as to promote the green and sustainable development of local agriculture.The main research results are as follows:1)Straw decomposition and nutrient release under different treatments showed the characteristics of fast in the early stage and slow in the later stage.The decomposition rate of each component of straw was hemicellulose > cellulose > lignin;the nutrient release rate of straw was K > P > C > N.After 365 d of straw returning to the field,the returning mode had a significant effect on the decomposition and nutrient release of the whole straw and its components,turning over and returning to the field was beneficial to the decomposition and nutrient release of the whole straw and its components;adding straw-decomposing inoculant significantly promoted the decomposition of straw and its components and the release of nutrients under the corresponding returning modes,among them,the most significant treatment was the no tillage straw mulching returning to the field.2)Different treatments can increase soil organic carbon and soil organic carbon content of various forms.During the growth period of maize,the soil total organic carbon content decreased first and then increased.There was a significant difference in soil total organic carbon content between the different returning modes,in which the soil total organic carbon content in straw turning over to bury returning to the field was higher than that in the no tillage straw mulching returning to the field;the soil total organic carbon content in each growth period was higher than that in the treatment without straw-decomposing inoculant.The soluble organic carbon,microbial biomass carbon,granular organic carbon and soil high,medium and low activity organic carbon were all increased;the soil microbial biomass carbon,soil total active organic carbon and the contents of each component were affected by the returning modes,the soil microbial biomass carbon and the soil total active organic carbon and the content of each component were significantly increased by rotary tillage straw turning over to bury returning to the field;deep loose straw turning over to bury returning to the field was most beneficial to increase the microbial biomass carbon,soil total active organic carbon,high and low active organic carbon.Add straw-decomposing inoculant can significantly increase the soluble organic carbon,microbial biomass carbon and particulate organic carbon,soil,high,medium and low activity of organic carbon,which under the condition of no tillage straw mulching returning to the field on soil soluble organic carbon to ascend effect is most obvious,and deep loose and rotary tillage straw turning over to bury returning to the field under the condition of soil microbial biomass carbon and particulate organic carbon promotion effect is most obvious,and can significantly improve soil active organic carbon,low active organic carbon and highly active organic carbon,the addition of active organic carbon was not significant.3)The soil available nutrient content was significantly affected by the returning modes and the straw-decomposing inoculant,but the effect on soil total nitrogen content was not significant.Turning over and returning to the field had a better effect on increasing the total nitrogen and available nutrients in the soil,compared with rotary tillageturning over to bury returning to the field,deep loose turning over and returning to the field had a better effect on improving the total nitrogen in the soil;under the three modes of straw returning to the field,the effect of soil available nutrients was the most significant under the condition of deep loose straw turning over to bury returning to the field,followed by rotary tillage straw turning over to bury returning to the field,and the no tillage straw mulching returning to the field was the most unfavorable to the increase of soil available nutrients.The addition of straw-decomposing inoculant could significantly promote the increase of soil total nitrogen content in each returning mode,among which the best effect was on the no tillage straw mulching returning to the field and the rotary tillage straw turning over to bury returning to the field;in the three modes of straw returning to the field,the contents of available nutrients in the soil could be improved by adding straw-decomposing inoculant,among them,the contents of alkali-hydrolyzed nitrogen and available potassium in the soil were more significant under the condition of turning over and returning to the field,while the contents of available phosphorus in the soil were more significant under the condition of straw mulching returning to the field. |
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