Effects Of Maize Straw On Soil Nutrient Conversion Based On The Mode Of Separation Of Maize Planting And Straw Returning

Effects of maize straw on soil nutrient conversion based on the mode of Separation of Maize Planting and Straw Returning were studied by situ simulation and microbial straw returning.The field in situ simulation experiment set up cross treatment with four levels of returning 0%(no straw),0.44%(total of conventional),0.88%(total of Planting and Returning)and 1.32%(3 times of conventional)and three different field depth 0-15 cm,15-30 cm,30-45 cm.The same four levels of straw treatment also set in micro-field,the field is divided into two parts of planting area and returning area.Soil NPK,trace elements,organic acids and maize root characteristics and yield were studied in the experiment.The results as follows:(1)Straw returning can increase the contents of available N,available P and available K in soil under the mode of Separation of Maize Planting and Straw Returning.The most significant is 30-45 cm soil layer of available N,available P and K increased most significantly in 0-15 cm.The increase of available K content was mainly due to the increase of exchangeable K,watersoluble K only significant in 0-15 cm.Promoting other forms of phosphorus into available P is the mainly affected to increase available P under the mode of Planting and Returning.There were no significant effect on soil total phosphorus and slow potassium.Meanwhile,it could improve the moderate stability organic phosphorus content and reduced the moderate active organic phosphorus content in the soil,and promote the transformation of soil organic phosphorus toward the moderate stability organic phosphorus.In addition,the effectiveness of maize straw returning to the field can also provide more nutrient that can be directly absorbed by the growth of maize in the next season.The availability of soil NPK in planting area is significant increase,available N was increased by 4.3%,14.3% and 20.0% respectively.The available phosphorus increased by 68.9%,60.2% and 88.5%,and available potassium increased by 14.7%,32.0% and 29.8%.(2)Straw returning of Separation of Maize Planting and Straw Returning can increase the contents of available Fe and available Zn in soil.The available Mn content has no obvious effect,is not conducive to the accumulation of soil available Cu.The soil available Fe and available Zn in 0-15 cm and 15-30 cm soil layers did not increase with the increase of straw returning,soil available Fe in 30-45 cm soil layer with straw increased,the effective Zn in 30-45 cm soil layer with the increase of straw to reduce the content.There was no significant difference between the treatments of available Mn in soils,and the effective Cu content in 15-30 cm and 30-45 cm soil layers decreased with the increase of straw but no significant.Corn stalks of planting and returning can increase the supply of available Fe and Zn in the next season.,The available Fe and Zn in the maize planting area increased significantly.Available Fe in the soil increased by 18.3%,23.6%,32.3%,and available Zn increased by 41.5%,37.8,59.3% respectively.(3)Straw returning can improve soil organic acid content under the mode of Separation of Maize Planting and Straw Returning.Among them,when the straw returned to field for 30 d,the soil organic acid content experienced a complicated process.The contents of organic acids in soils of 0-15 cm soil layer were higher than those in control,and the contents of soil organic acids in 30-45 cm soil layer were lower than those in control.With the increase of returning time,the contents of organic acids in each treatments were significantly increased.During the period from 90 d to 150 d,the contents of soil organic acids were at a high level,and the contents of soil organic acids in each treatments were significantly decreased from 150 d to 360 d.Corn stalks can increase the soil organic acid content for the next season maize growth under the mode of Planting and Rerturning.The soil organic acid content increased by 6.8%,14.5% and 11.6%,respectively,in the corn plantation area after the straw returning.In addition,the increase of soil organic acid content was beneficial to the increase of available nutrient in soil.Soil organic and soil available K,available P,available Fe and available Zn showed significant positive correlation in 0-15 cm soil layer.Soil organic acid And available P,available Fe in 30-45 cm soil layer was positively correlated.(4)Straw returning of Separation of Maize Planting and Straw Returning can promote the growth of maize roots at seedling stage,increase maize root dry weight,root volume,total root length and root surface area,increase maize yield.The dry weight of each treated root was increased by 7.9%,12.2% and 8.6%,respectively,root volume increased by 1.9%,14.0% and 10.4%,total root length increased by 3.0%,6.6% and 6.9%,Root surface area increased by 8.5%,18.2% and 16.7%,meanwhile the yields of R1 and R3 were increased by 7.1% and 21.2% respectively.