我国每年至少有50亿t沃土付之东流,伴随流失的N、P、K养分也有上亿t。据不完全统计,我国40年来因水土流失损失的土地超过266.7万hm~2。 据有关部门介绍,今年夏天长江中下游地区发生了历史罕见的洪涝灾害,除气象因素外,上游水土流失导致泥沙在中下游河道、湖泊沉积,是主要原因之一。由于森林被砍伐, At least 50 billion tons of fertile soil are going to be lost each year in our country. With the loss of N, P and K nutrients, there are over 100 million tons of nutrients. According to incomplete statistics, the land lost due to soil erosion over the past 40 years has exceeded 2.667 million hm 2. According to relevant departments, rare floods have occurred in the middle and lower reaches of the Yangtze River this summer. Apart from the meteorological factors, the upstream soil and water erosion led to the sediment deposition in the middle and lower reaches of the river and lakes, which is one of the major reasons. Due to the deforestation,