赤红壤植蔗坡地坡面径流及溶解态氮磷流失特征

为探究南方高强度、高频次降雨下赤红壤区坡耕地土壤侵蚀及氮磷养分流失的特征，基于野外径流小区原位观测试验，通过测定自然降雨下赤红壤植蔗坡地坡面径流和溶解态氮磷流失量，探讨自然降雨下甘蔗种植对赤红壤坡面径流及溶解态氮磷流失的影响。结果表明：(1)2019年和2020年，径流量分别为1111.3 m~3/hm~2和3269.4 m~3/hm~2,硝态氮(NO~-₃-N)流失量分别为1.39 kg/hm~2和15.60 kg/hm~2,铵态氮(NH~+₄-N)流失量分别为0.37 kg/hm~2和1.02 kg/hm~2,可溶性磷流失量分别为0.20 kg/hm~2和0.27 kg/hm~2。2019年和2020年植蔗坡地径流及溶解态氮磷流失量均集中在6月份，占流失总量的45%以上，硝态氮(NO~-₃-N)是径流氮素流失的主要形式，占79%以上。此外，2019年和2020年5月至8月，侵蚀性降雨场次分别为18次和23次，侵蚀性降雨量分别为407.8 mm和668.0 mm。(2)不同侵蚀性降雨条件下，植蔗坡地溶解态氮磷流失量及其...

Characteristics of runoff and the dissolved nitrogen and phosphorus loss in sloping land with planting sugarcane of lateritic soil

The characteristics of soil loss and nutrient loss in sloping land are quitely different among different areas of China, and crop patterns also have significant impacts on these indicators. The objectives of this study were as follows:1) to explore the characteristics of soil erosion and nutrient loss in sloping land with planting sugarcane of lateritic soil; and 2) to analyze the impacts of sugarcane growing stage and natural rainfall characteristics on soil erosion and nitrogen and phosphorus loss characteristics. This research based on the in-situ observation test of runoff plot and measured the loss of runoff, dissolved nitrogen, and phosphorus in sloping land with planting sugarcane. The amounts and concentrations of nitrate nitrogen (NO₃^--N), ammonium nitrogen (NH₄⁺-N), and dissolved phosphorus (DP) under individual natural rainfall during May to August in 2019 and 2020 were observed. The results showed that:(1) in 2019 and 2020, the runoffs, nitrate nitrogen (NO₃^--N), ammonium nitrogen (NH₄⁺-N), and dissolved phosphorus (DP) loss were 1111.3 m³/hm² and 3269.4 m³/hm², 1.39 kg/hm² and 15.60 kg/hm², 0.37 kg/hm² and 1.02 kg/hm², 0.20 kg/hm² and 0.27 kg/hm², respectively. The runoff and its dissolved nitrogen and phosphorus loss in sloping land with planting sugarcane under 2019 and 2020 were both concentrated in June, which accounted for more than 45%, and NO₃^--N was the main form of nitrogen loss in runoff, which accounted for more than 79% of total nitrogen loss. Besides, the times of individual erosive rainfall were 18 and 23, and the erosive rainfall amounts were 407.8 and 668.0 mm from May to August in 2019 and 2020, respectively. (2) The amounts of dissolved nitrogen and phosphorus loss and their concentrations in sloping land with planting sugarcane showed great fluctuation under different erosive rainfalls and stages of sugarcane growth. There were obvious differences in the annual distribution of erosive rainfall between observation period of 2019 and 2020, which were both concentrated in June, which accounted for more than 35% of total rainfall. In the early stage of sugarcane growth (from May to June), the losses of dissolved nitrogen and phosphorus and their concentrations showed an upward trend, while in the late stage of sugarcane growth (from July to August), they showed a fluctuating downward trend. (3) There was a significantly positive correlation between runoff and rainfall and maximum 30 min rainfall intensity, meanwhile, there was a significantly positive correlation between runoff and the loss of nitrate nitrogen (NO₃^--N), ammonium nitrogen (NH₄⁺-N), and dissolved phosphorus (DP). The results can provide a theoretical basis for clarifying the soil erosion characteristics of sloping land with planting sugarcane in the lateritic soil region of southern China.