不同措施黄绵土坡地暴雨侵蚀及磷素流失特点

Characteristics of soil erosion and phosphorus loss from loessial sloping land under different measures during heavy rainstorms

为探讨不同管理措施对10°、15°和20°黄绵土坡面侵蚀及磷素流失的影响,本文以60 mm·h^-1为试验雨强,采用室内人工模拟降雨试验方法,以CK(裸坡,0%生物炭,平作)为对照,分析C1(裸坡,0%生物炭,横垄)、C2(裸坡,3%生物炭,平作)、C3(裸坡,3%生物炭,横垄)、C4(裸坡,6%生物炭,平作)、C5(裸坡,6%生物炭,横垄)、C6(植被,0%生物炭,平作)、C7(植被,0%生物炭,横垄)、C8(植被,3%生物炭,平作)、C9(植被,3%生物炭,横垄)、C10(植被,6%生物炭,平作)和C11(植被,6%生物炭,横垄)多措施下黄绵土坡地泥沙及磷素流失特征。结果表明:不同坡度下C1、C6、C7、C8、C9措施能有效降低黄绵土坡面侵蚀及磷素流失;施加生物炭(C2~C5、C8~C11)加剧了坡地尤其是陡坡的土壤侵蚀和磷素流失;在不同坡面上布设植被措施(C6~C11)均具有拦沙固磷作用,在15°坡面效果最优;横垄措施(C1、C3和C5)减沙固磷效应随坡度增大而减弱,在20°下易失效,故小于10°坡面上宜推广应用横垄措施;植被与横垄措施相结合(C7、C9和C11)在不同坡度下的消减率均在50%以上,故在实际农业生产中建议使用横垄搭配植被措施。黄绵土坡面磷素流失以颗粒态(PP)为主,PP/TP流失比例多在80%以上,并随坡度增大而增大;3种坡度下施加生物炭(C2、C4)均使PP占比增至90%以上,而横垄和植被措施能有效降低坡面PP/TP比例。综上,缓坡上设置横垄,陡坡上设置植被或者在植被覆盖基础上合理搭配横垄和3%生物炭措施,均有利于阻控黄绵土坡面土壤侵蚀和磷素流失。

A simulated rainfall experiment of 60 mm·h^-1 was conducted to investigate the effects of different management measures on slope erosion,and sediment and phosphorus loss on loessial sloping land of 10°,15°,and 20°for CK(bare slope,0%biochar,flat tillage),C1(bare slope,0%biochar,horizontal ridge),C2(bare slope,3%biochar,flat tillage),C3(bare slope,3%biochar,horizontal ridge),C4(bare slope,6%biochar,flat tillage),C5(bare slope,6%biochar,horizontal ridge),C6(vegetation coverage,0%biochar,flat tillage),C7(vegetation coverage,0%biochar,horizontal ridge),C8(vegetation coverage,3%biochar,flat tillage),C9(vegetation coverage,3%biochar,horizontal ridge),C10(vegetation coverage,6%biochar,flat tillage),and C11(vegetation coverage,6%biochar,horizontal ridge).The results showed that C1,C6,C7,C8,and C9 effectively reduced the soil erosion and phosphorus loss of different loessial slopes.Soil erosion and phosphorus loss were aggravated by the application of biochar(C2~C5,C8~C11),especially on steep slopes.Vegetation coverage(C6~C11)effectively slowed sediment and phosphorus loss on different slopes,and the controlling effect was optimal on the 15°slope.The mitigation effect of the horizontal ridge on the bare slope(C1,C3,and C5)decreased as the slope increased and was liable to fail at 20°;thus the horizontal ridge was recommended for slopes≤10°.The combination of vegetation coverage and horizontal ridge(C7,C9,and C11)effectively reduced sediment and phosphorus loss for different slopes with a reduction rate of≥50%and was advisable for agricultural production.Particulate phosphorus(PP)was the primary form of phosphorus loss on loessial sloping land,accounting for more than 80%in most scenarios and increasing with increased slope.Applying biochar increased the proportion of PP loss,the proportion of C2 and C4 accounted for more than 90%,and the installation of the horizontal ridge and vegetation coverage reduced the PP/TP proportion.Therefore,the horizontal ridge on a gentle slope,a reasonable combination of vegetation coverage,and a 3%biochar application on a steep slope were beneficial for controlling the soil erosion and phosphorus loss of loessial slopes.