Response of Cultivated-Layer Water-Holding and Drought Resistance Performance and Productivity to Erosion Degree in Purple Soil Sloping Farmland
[Objective]The aim of this study was to analyze the water-holding performance and yield response characteristics of purple soil slope farmland under erosion conditions,so as to provide the theoretical basis for regulating seasonal drought and moisture use efficiency of sloping farmland,and improve yield of sloping farmland under erosion conditions.[Method]Soil erosion simulation method was adopted,with the non-eroded plot as the control group(S-0),and based on erosion degrees of 5 cm(S-5),10 cm(S-10),15 cm(S-15),20 cm(S-20)and 3 management measures(no fertilizer(CK),fertilizer(F),biochar + fertilizer(BF)).The variation of water retention and drought resistance of slope soil layer and the variation of corn yield and response to erosion degree were compared and analyzed.[Result](1)The core soil layer soil water-holding performance was stronger.At the same level of soil moisture suction,the reduction amplitude of soil volume moisture content in the tillage layer(13.9%-18.2%)was greater than that in the core soil layer(9.8%);with interannual changes,the volumetric moisture content of the cultivated soil increased maximum at S-5(14.2%),while the core soil layer showed the maximum at S-15(33.2%).(2)The total storage capacity,active storage capacity,maximum effective storage capacity,and effective moisture content of sloping farmland soil showed a parabolic variation pattern with increasing erosion.With interannual changes,the maximum increase in maximum effective storage capacity(44.7%)at various erosion levels was at a relatively strong erosion level(S-15),while the maximum increase in effective moisture content,maximum water storage capacity,and maximum single acceptance rainfall was at weak erosion levels(S-0 to S-10).(3)The corn yield of slope cultivated land decreased with the increase of erosion,which was positively correlated with the maximum effective storage capacity and field water capacity;with interannual changes,the yield reduction effect of sloping farmland decreased under different degrees of erosion,and the yield change showed a certain lag with the deterioration of erosion,that is,there was no significant reduction in yield in the year of erosion.(4)The maximum effective storage capacity of sloping farmland soil under erosion conditions was significantly affected by the clay content,capillary porosity,and organic matter content(P<0.01);The field water capacity was significantly correlated with soil depth,organic matter,silt,and porosity(P<0.01).[Conclusion]The strength of the soil water-holding and drought performance was mainly affected by the merits of the soil structure.The soil structure of slope farmland under erosion conditions could be improved by combining deep tillage and biochar+fertilizer management measures,which could effectively regulate the water-holding and drought resistance of erosive cultivated-layer of sloping farmland and improve crop yield of sloping farmland under erosion conditions.
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