Effects Of Different Straw Return Patterns On Soil Physical Properties And Maize Growth

In recent years,due to unreasonable tillage measures and excessive application of chemical fertilizers,problems such as poor soil structure,reduced water storage and water retention capacity,and soil compaction have become increasingly serious,resulting in a decline in the productivity of cultivated land.Northeast China is an important corn production base in China,which produces a huge amount of straw resources every year.Returning straw to the field is an important measure to improve soil fertility and maize yield.However,due to the single method of returning straw to the field and the difficulty of returning the straw to the field,the utilization of agricultural resources of straw is limited.Therefore,this paper adopted the experimental method of field micro-plot to discuss the effects of different patterns of straw on soil physical properties and maize growth.In this study,three returning patterns of straw mulching（BF）,shallow straw returning（QH）,and deep straw returning（SH）were set,and no straw returning（CK）was used as the control.The effects of soil aggregate stability,soil bulk density,soil moisture characteristics,soil compressive properties under different water suction,and maize growth after returning to the field for one year were discussed,and the relationship between soil physical properties and maize yield was analyzed,in order to provide a scientific basis for the selection of straw returning patterns.The main results are as follows:（1）Different straw returning patterns improved the soil structure.In the 0～20 cm soil layer,compared with the CK treatment,the macroaggregate content(R_0.25),the mean weight diameter（MWD）,the geometric mean diameter（GMD）of the QH and BF treatments significantly increased by 26.64%,24.04%,21.30%and 23.93%,19.16%,20.81%;in the20～40 cm soil layer,compared with the CK treatment,the macroaggregate content,MWD and GMD of the SH treatment were significantly increased by 28.60%,30.21%and 20.88%,and the stability of soil aggregates was enhanced.（2）Different straw returning patterns reduced the soil bulk density of the 0～20 cm and20～40 cm soil layers,and increased the soil moisture content.In the 0～20 cm soil layer,compared with the CK treatment,the soil saturated water content of the straw returning treatment increased significantly by 6.82%～10.21%,and the field water holding capacity and wilting water content of the QH and SH treatments increased significantly by 7.83%,8.13%and 6.54%,6.10%;in the 20～40 cm soil layer,compared with the CK treatment,the soil saturated water content,field capacity and wilting water content of SH treatment increased significantly by 10.01%,16.85%and 10.95%.SH treatment significantly improved the soil physical quality index and specific water capacity of 0～20 cm and 20～40 cm soil layers.（3）The preconsolidation stress increased gradually with the increase of soil water suction,when the water suction was 1000 k Pa,the preconsolidation stress of each soil layer under SH treatment reaches the maximum.Different straw returning methods all improved the rebound index,in the 0～20 cm soil layer,the rebound index was larger under QH treatment,and in the 20～40 cm soil layer,the rebound index was larger under SH treatment.The compression index was significantly affected by water suction,in the 0～20 cm soil layer,the 6k Pa-CK combination had a smaller compression index,and in the 20～40 cm soil layer,the 33k Pa-CK combination had a smaller compression index.（4）In each growth period of maize,the leaf area and chlorophyll SPAD value of maize increased significantly in BF treatment,and the plant height and stem diameter of maize in SH treatment were the best.Maize yields increased to varying degrees after straw returning,among which the maize yields of BF and SH treatments increased significantly by 23.37%and 22.02%compared with CK treatments.（5）In the 20～40 cm soil layer,the aggregate stability index,soil saturated water content and bulk density were the important factors affecting maize yield.Combining all the indicators,deep straw returning was more conducive to the improvement of soil physical properties and maize yield in 0～20 cm and 20～40 cm soil layers,which was better than other straw returning patterns.