质量指数表征模拟降雨下土壤坡面养分的流失特性

通过室内自动模拟降雨系统,设置模拟降雨试验,运用土壤单质量指数(SSQI)和土壤综合质量指数(SSCI),研究了模拟降雨对3种类型土壤(棕壤、褐土与红壤)坡面养分流失及土壤质量变化的影响。结果显示:降雨造成了3种类型土壤坡面不同程度的氮素流失,土壤全氮指数均有所降低,并以坡下部降低最多;表下层坡面土壤全氮指数以棕壤降低最多,分别为褐土的1.33倍和1.79倍、红壤的9.28倍和3.45倍。降雨均提高了3种类型土壤坡面有效磷的含量,有效磷指数除棕壤下层坡面降低了3.98%外,其余土壤坡面升高了4.00%~47.73%,并以红壤表下层坡面的升高幅度最大。模拟降雨下,土壤速效钾含量变化受土壤类型影响较大,3种类型土壤中,红壤坡面的速效钾指数有较大幅度升高,褐土坡面降雨前后基本持平,而棕壤坡面有小幅降低。模拟降雨后,棕壤与褐土表下层坡面综合指数分别降低了33.62%、35.34%与22.53%、11.73%,而红壤反而升高了18.93%与7.00%。

Quality Indices on Nutrient Loss Characteristics of Soil Slope under Simulated Rainfall

The nutrient loss characteristics of three soils (brown soil, cinnamon soil and red soil) were studied by using indoor automatic rainfall simulation system, soil single quality index (SSQI) and soil comprehensive quality index(SCQI).The results showed that the simulated rainfall caused the different loss levels of nitrogen on all three tested soil slopes, total nitrogen index all decreased, and decreased most at all the bottom slopes; total nitrogen indices on both surface and lower slope reduced most in brown soil, which was 1.33 times and 1.79 times of cinnamon soil, 9.28 times and 3.45 times of red soil, respectively. The available phosphorus content was increased by simulated rainfall, except brown soil’s available phosphorus index reduced by 3.98%, the available phosphorus index on other soils’ slopes increased from 4.00% to 47.73%, increased most in the surface lower slope of red soil. Under simulated rainfall, rapidly available potassium index of red soil increased significantly, that of cinnamon soil changed little, and that of brown soil decreased slightly. After simulated rainfall, surface and lower slope comprehensive indices of brown soil and cinnamon soil were reduced by 33.62%, 35.34% and 22.53%, 33.62%, respectively, while that of red soil increased by 18.93% and 7.00%.