模拟降雨下茎秆直径对紫色土坡面植物篱-草沟系统氮磷流失的影响

    Effects of Stem Diameter on Nitrogen and Phosphorus Losses in Simulated Hedgerow-grass Ditch System on Purple Soil Sloping Lands

      摘要
    • 摘要: 植物篱-草沟系统是结合植物篱和生态草沟的复合措施, 在紫色土坡面已广泛应用。茎秆直径是影响植物阻控坡面氮磷流失的重要指标, 但茎秆直径对植物篱-草沟系统坡面氮磷流失的影响还不清楚。本研究设置5种植物篱茎秆直径, 分别为0 mm(对照, CK)、1 mm(T1)、2 mm(T2)、4 mm(T3)、8 mm(T4), 通过室内模拟降雨试验探究植物篱-草沟系统地表径流总氮(TN)、总磷(TP)的流失特征, 评估不同茎秆直径对紫色土坡面植物篱-草沟系统氮磷流失的影响。结果表明, T1、T2、T3、T4处理的泥沙削减率比CK显著高39.95%、59.86%、83.60%、94.42%(P < 0.05), T3、T4处理的泥沙拦截效益显著高于T1(P < 0.05)。各处理径流TN、TP流失浓度随降雨历时而变化, 浓度范围分别为2.89~10.08、0.31~0.62 mg·L-1。与CK相比, T2、T3、T4处理的TN平均流失浓度显著削减(P < 0.05), 且T2、T3、T4处理的TN流失浓度削减效果显著高于T1(P < 0.05)。与CK相比, T2、T4的TN流失量和流失率分别显著降低51.92%、60.66%和49.37%、58.75%(P < 0.05)。TN、TP流失浓度及TP流失量分别与茎秆直径呈指数负相关(P < 0.05)。研究结果可为紫色土坡耕地农业面源污染防控措施优化提供理论依据。

       

      Abstract: Hedgerow-grass ditch system, a comprehensive measure combining hedrgerow and ecological grass ditches, has been widely used on purple soil slopes. Stem diameter is an important variable that affects the plants′ controlling effectiveness of nitrogen and phosphorus losses on slopes, but the effects of stem diameter on nitrogen and phosphorus losses on slopes with hedgerow-grass ditch system is not clear. In this study, we set up five kinds of plant hedge stem diameters, i.e., 0 mm (control, CK), 1 mm (T1), 2 mm (T2), 4 mm (T3), and 8 mm (T4), and investigated the characteristics of total nitrogen (TN) and total phosphorus (TP) loss of surface runoff from the plant hedge-grass ditch system through indoor simulated rainfall test, and evaluated the nitrogen and phosphorus loss reduction benefits of the different stem diameters of the plant hedge-grass ditch system in the purple soil slopes. The results show that (1) The sediment reduction rates of T1, T2, T3 and T4 were significantly higher than those of CK treatment with 39.95%, 59.86%, 83.60% and 94.42% (P < 0.05), respectively; and the sediment interception benefits of T3 and T4 treatments were significantly higher than those of T1 (P < 0.05). (2) Under each treatment, the changes of runoff TN and TP loss concentration with rainfall calendar time were 2.89-10.08 and 0.31-0.62 mg·L-1, respectively; compared with CK, the average loss concentration of TN was significantly reduced in T2, T3 and T4 (P < 0.05). The reduction of TN loss concentration in T2, T3, and T4 treatments was significantly higher than the reduction of T1 treatment (P < 0.05). (3) Compared with CK, the TN loss and loss rate under T2 and T4 treatments were significantly reduced by 51.92%, 60.66% and 49.37%, 58.75%, respectively (P < 0.05). (4) The concentration losses of TN and TP and loss amount of TP had significant negative exponential correlations with stem diameter (P < 0.05). The results of this study provide theoretical basis for the optimization of agricultural non-point source pollution control measures in purple soil sloping lands.

       

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