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questions :Universal soil lossequation explain it's importance in soil conservation
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[Member (365WT)]answers [Chinese ]Time :2019-05-22
1. Declining or even losing land productivity: China's soil erosion area has expanded to 1.5 million square kilometers, accounting for 1/6 of China's total, and 5 billion tons of soil is lost every year. The amount of nitrogen, phosphorus and potassium lost in the soil is estimated to be 40 million tons, which is equivalent to the amount of chemical fertilizer applied in China for the current year, equivalent to an economic loss of 2.4 billion yuan. The amount of sediment lost in the Yangtze River and the Yellow River is 2.6 billion tons per year. The organic fertilizer contained in it is equivalent to the total amount of 50 fertilizer plants with an annual output of 500,000 tons. It is no wonder that some people say that the Yellow River is not the sediment, but the blood of the Chinese nation. Such large areas of fertile soil and nitrogen, phosphorus and potassium fertilizers have been washed away, which will inevitably lead to a decline or even complete loss of land productivity.
2. Sedimentary rivers, lakes and reservoirs: Although the water and soil loss in Zhejiang Province is relatively light, the riverbed with 8 water systems in the province has generally increased by 0.2-0.1 meters, and the inland navigation mileage is currently reduced by 1000 kilometers compared with the 1960s. For example, before 1958, a 10 ton wooden boat could be used from Qixian County to Caofeijiang. Due to too much silt in the riverbed, it has now been forced to suspend, the surface water resources have turned into sand, and the aviation construction company has been changed to "Huangsha" company.
Due to the excessive wind and sand in Dongting Lake, Hunan Province, more than 1,400 hectares of sandbars are exposed every year. The lake area has been reduced from 3,915 square kilometers in 1954 to 2,740 square kilometers in 1978. What is more serious is that the water surface of Dongting Lake has been 3 meters above the land of the lake, which has lost its role in flooding the Yangtze River. This is a very serious problem.

The water and soil loss in several river basins such as Jialing River, Minjiang River and Lancang River in Sichuan Province is also very serious. About 20% of the sediment is deposited in the reservoir. According to the prediction of relevant experts, as of this, in the next 50 years, some reservoirs in the Yangtze River Basin will be flattened or become silt.
3. Pollution water quality affects ecological balance: At present, a prominent problem in China is the serious pollution of water quality in rivers, rivers and lakes (reservoirs). Soil erosion is an important cause of water pollution. The water quality of the Yangtze River is being polluted as a typical example.

It can be seen that the harmfulness of soil erosion is not only great, but also has long-term effects. The seriousness of the problem must be fully estimated.
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