中国红壤丘陵区水土流失规律与土壤允许侵蚀量的研究

Regularity of Erosion and Soil Loss Tolerance in Hilly Red-Earth Region of China

在 8°～ 15°的红壤坡地上 ,对水土流失做了 14年的定位观察。结果表明 ,水土流失与土壤坡度和植被覆盖度密切相关。红壤坡地一经开发利用 ,径流量就成倍地减少 ;而侵蚀量在开始的头 2年成倍增加 ,第 3年后趋于稳定。土壤侵蚀量与坡度呈极显著的对数正相关 ,坡度每增加 1° ,年土壤侵蚀量递增约 12 0t·km-2 ;土壤侵蚀量与植被覆盖度呈显著的负指数相关 ,当植被覆盖度 >6 0 %时 ,每年土壤侵蚀量在 2 0 0t·km-2 以下 ;土壤侵蚀量与耕种方式密切相关 ,等高耕种的侵蚀量仅为顺坡耕种的 1/6。应用土壤肥力平衡观点 ,首次提出了Q2 红色粘土母质发育的红壤年土壤侵蚀允许指标为 <30 0t·km-2 。

s: Fixed site observations for 14 yr long term investigation on the soil water losses in the sloping red earth (slope 8°-15°) showed that soil water losses were closely correlated with land slope and vegetative coverage. Runoff rate in sloping red earth could be reduced duplicately by exploitation, while the soil erosion was enhanced duplicately during the first 2 years after exploitation. Subsequently, it tended to be stable. Soil erosion was highly positively correlated with land slope, i.e. soil erosion was increased by 120 t·km -2 per year with a slope increase of 1°. On the contrary, soil erosion was highly negatively correlated with vegetative cove rage, i.e. soil erosion was limited to below 200 t·km -2 per year as the vegetative coverage exceeded 60%. Furthermore, soil erosion was highly related with planting patterns, i.e. soil erosion in contour cropping pattern would be one sixth of that in straight cropping. Based on the view of soil nutrient balance and test data, it was suggested that soil loss tolerance in Q 2 red clay derived red earth should be lower than 300 t·km -2 per year.