Effects Of Methods Of Different Straw Returning On Growth And Development Of Maize And Soil Properties Of Tillage Layer

In order to provide theoretical support for the production practice of straw returning to the field in Heilongjiang Province,the effects of different straw returning methods on the growth and development of maize and the properties of topsoil were studied in this experiment.The experiment adopted the large area contrast design,took the straw not to return the field(CK)as the control,set up the straw cover to return the field(J1),the straw buried to the field(J2),the straw shredded to the field(J3)four treatments.The effects on the growth and development of maize and the physical and chemical properties of topsoil were analyzed.The main conclusions of the study are as follows:1.There were significant differences in plant height and yield,1000-grain weight,seedling quality and leaf area index under different straw returning methods,but there was no significant difference in panicle number and grain number per spike.Compared with CK,the seedling quality and plant height were increased by 17.33% and 7.80% respectively.The maximum leaf transport rate and leaf contribution rate were 14.75% and 3.12% respectively,followed by straw shredding and returning to the field.From flowering stage to maturity stage,the photosynthetic rate of maize buried in the field was higher than that in other returning methods.The 1000-grain weight increased the most(11.89%),and the leaf area index(Lai)increased the most(11.38%).The order of maize yield increase was as follows: burying to field > broken mixture to field > mulching to field > CK,in which the increase of maize yield was significant(8.70%).2.In the early growth stage,the soil temperature of ploughing layer was the highest,followed by broken mixture returning to field,mulching and returning field was the lowest,but the soil temperature was the highest at filling stage,and the order of soil water content was mulching returning field > broken mixed returning field > burying returning field > CK.There was no significant difference in soil bulk density in 0-10 cm plough layer with different straw returning methods,but the difference in soil bulk density between 10-20 cm and 20-30 cm plough layer reached a very significant level,among which the decrease of soil bulk density was the largest.The porosity of 0-10 cm topsoil at seedling stage and flowering stage decreased by 11.29% and11.61% respectively,but there was no significant difference in soil porosity between 10-20 cm plough layer at seedling stage and 20-30 cm plough layer at seedling stage,and the difference ofsoil porosity at seedling stage and 20-30 cm plough layer reached significant level.The soil porosity of 10-20 m and 20-30 cm increased by 33.79% and 30.65% respectively at flowering stage,and the difference of soil field water capacity reached extremely significant level at different growth stages.Among them,the field water holding capacity of 0-30 cm plough layer soil was more beneficial to the return of broken and mixed soil,and different straw returning methods were beneficial to the formation of large aggregate structure of > 1 mm soil,among which the effect of turning over and returning to the field was the most obvious,with an increase of 30.30%.3.The effects of different straw returning methods on soil enzyme activities were different.the activities of soil urease and sucrase were significantly different at flowering stage,and there were significant differences between soil phosphatase at grain filling stage and soil sucrase at maturity stage.Due to the obvious effect of straw mulching on water conservation in the early growth stage and heat preservation in the late growth stage,mulching and returning to the field could increase the activities of urease and phosphatase in the soil,and the activities of urease and phosphatase in the soil were significantly promoted at the filling stage.Compared with CK,it increased by 21.58% and 18.90%,respectively.At the same time,the activities of soil cellulase and sucrase were also increased,especially in broken mixed soil,in which the activities of soil cellulase and sucrase were 37.29% and 51.55% higher than those of CK.