Effects Of Different Straw Returning And Mulching Treatments On Soil Properties And Water Use Efficiency Of Winter Wheat In Guanzhong Plain

Wheat is one of the most important crops in the Guanzhong Plain of China.However,drought,water and fertilizer shortaged are major problems in the study area,which are negative effects on crop yield and soil quality.The straw return into the soil is good practice to improve the soil organic matter sink,facilitate crop yield and improve soil fertility status.Biochar returning to the field can promote the growth and development of crops and improve soil fertility.Therefore,it is important to explore straw return methods for high-efficiency green and water-storing,improve soil fertility,and improve crop yield.This study included an ordinary straw mulching(SM),powdered ordinary straw plowed into soil(SP),ammoniated straw plowed into soil(AP),biochar plowed into soil(BP),leisure in summer and straw mulching in winter(FS)and plastic film mulching(PM)six treatments compared with control with no straw returning(CK).The field experiment was conducted to explore the effects of different pretreated straw returning and plastic film mulching methods on soil fertility and crop yield.This study can enrich the technical system of the straw returning methods,and provide theoretical basis and technical support for the rational and an efficient utilization of straw residues.The main conclusions of this study are as follows:(1)straw renturn and BP increased soil SOC content.Straw renturn increased the stability of soil aggregates,while different mulching treatments had different effects on soil water-stable aggregates.The effect of straw returning on soil water-stable aggregates in 0～10 cm soil layer was greater than 10～20 cm.Returning straw to the field is beneficial to increase soil organic carbon of 0-20 cm soil.The SM has significant effect on the soil organic carbon in 0-10 cm soil depth over the SP and AP.The result was reversed at 10-20 cm soil depth.However,ammoniated straw was superior to ordinary straw on soil organic carbon content;The average SOC in the two years in 0-10 soil layer followed the order of SM>SP>AP>CK,which were increased by 16.17 %,15.42 % and 6.29 % compared with that of CK,respectively;And in10～20 cm soil layer,the order was AP>SP>SM>CK,which were increased by 9.30 %,8.97 %and 2.95 % compared with that of CK,respectively.BP increased soil SOC content by 8.99 %and 5.13 % in 0-10 cm and 10-20 cm soil layer,compared with that of CK,respectively.PM increased the content of >5 mm soil water-stable aggregates,thus increasing the stability of soil aggregates.FS significantly reduced the content of >5 mm soil water-stable aggregate and increased the content of 0.5-1 mm soil water-stable aggregates and that leaded to a decrease in the stability of soil aggregates.(2)Straw returning increased soil MBC and MBN content.The plowed field increased more than mulched soil.Different mulching treatments had different effects on soil MBC and MBN content.SM,SP,AP,BP and FS increased the soil AK content.The average MBC of soil in 0～10 cm soil layer followed the order of AP>SP>SM>CK,which were increased by 29.17 %,26.26 % and 17.66 % compared with that of CK,respectively.In the 10～20 cm soil layer,the order was SP>AP>SM>CK,were increased by 15.77 %,15.30 % and 3.38 % respectively;FS increased soil MBC content.while PM decreased soil MBC content.The average MBC value of soil in 0-10 cm soil layer followed the order of FS>BP> CK>PM,were increased by 9.73 %,0.94 %,and-16.52 % compared with that of CK,respectively.In the 10～20 cm soil layer,the order was FS>CK>BP>PM,which were increased by 0.55 %,-8.48 % and-9.53 % compared with that of CK,respectively.Straw returning significantly increased the average value of AK in 0-10 cm soil layer.SM,SP and AP increased by 21.71 %,17.56 % and 16.08 % compared with that of CK.(3)Straw returning and mulching treatments were significantly increased the grains yield of winter wheat,and increased the water use efficiencies.The maximum grains yield and aboveground biomass of winter wheat was recorded by the AP.were increased by 29.60 % and19.6 % compared with that of CK,respectively.AP significantly increased the water use efficiencies by 32.51 % compared with that of CK.Comparing different mulching treatments,the maximum grains yield and aboveground biomass of winter wheat was recorded by the PM.were increased by 40.14 % and 27.9 % compared with that of CK,respectively.The average water use efficiencies of PM increased by 41.10% compared with that of CK.