秸秆覆盖对西南喀斯特坡地幼龄橘园产流产沙的影响

喀斯特坡地幼龄橘园人为扰动剧烈,容易发生土壤侵蚀。秸秆覆盖是坡地常用的水土保持措施,但其在喀斯特坡地橘园的水土保持效益还不清楚。通过人工土槽模拟降雨试验,研究了水稻秸秆覆盖对喀斯特坡地幼龄橘园产流产沙的影响,试验设置了2个雨强(60 mm/h和120 mm/h)和4种水稻秸秆覆盖度(0,20%,50%和80%)。结果表明:(1)秸秆覆盖减小地表径流的效果受降雨强度控制。在中雨强(60 mm/h)条件下,秸秆覆盖可以有效降低地表径流系数。在大雨强(120 mm/h)下,只有20%覆盖度可以减少地表径流系数;(2)在中雨强(60 mm/h)条件下,20%和50%的秸秆覆盖显著增加壤中流和地下径流量; 在大雨强(120 mm/h)条件下,20%的秸秆覆盖显著增加了壤中流量,50%和80%秸秆覆盖度对壤中流量影响不显著;(3)秸秆覆盖可以有效减少地表土壤侵蚀总量,地表土壤侵蚀总量与秸秆覆盖度呈负相关。(4)秸秆覆盖减弱了地表径流的携沙能力,在50%和80%秸秆覆盖度时地表径流的携沙能力得到显著减弱。结果可为喀斯特坡地幼龄橘园合理布设秸秆覆盖措施提供科学依据。

Effect of Straw Mulch on Runoff and Sediment Production in Young Citrus Orchards in Southwest Karst

The young sloping citrus orchard in karst area is prone to soil erosion because of the severe factitious disturbance.Straw mulch is a common measure to conserve water and soil on sloping land,but the efficiency of straw mulch in the soil and water conservation of citrus orchards on sloping land in karst area is not clear.The present study used simulated rainfall experiment to study the effects of straw mulch on runoff and sediment production in young citrus orchards in sloping fields of karst area.Two rainfall intensities(60 mm/h and 120 mm/h)and four levels of straw cover rates(0,20%,50%,and 80%)were set up.The results show that:(1)the effect of Straw mulch on reducing surface runoff coefficient is controlled by rainfall intensity;under the condition of medium rainfall intensity(60 mm/h),straw mulch can effectively reduce the coefficient of surface runoff;under the condition of high rainfall intensity(120 mm/h),only 20%coverage can reduce the runoff coefficient;(2)under moderate rainfall intensity(60 mm/h),20%and 50%straw mulch can significantly increase interflow and underground runoff,and under heavy rainfall intensity(120 mm/h),20%straw mulch significantly increases interflow,the effects of 50%and 80%straw coverage on interflow are not significant;(3)straw mulch can effectively reduce the total amount of soil erosion;the total soil erosion and straw mulch are negatively correlated;(4)straw mulch reduces the sediment carrying capacity of surface runoff,and the sediment carrying capacity of surface runoff decreases significantly at 50%and 80%straw mulching levels.This study can provide the scientific basis for the rational arrangement of water and soil conservation measures in young citrus orchards in sloping land of karst area.