Effects Of Conservation Fertilization On Nitrogen Loss And Crops Yield In Northern Erhai Lake Basin

Water pollution of Erhai lake"mother lake of Dali"caused by nitrogen loss in farmland is becoming more and more serious, it is necessary to seek the appropriate conservation fertilization managements to effectively enhance the crops economic benefit and reduce the risk of nitrogen loss. An investigation was carried out to know soil basic nutrient and the problems in agricultural production, and a field experiment had been carried out with a typical garlic-rice rotation mode to study the effects of Conservation FertilizationⅠ(the management of optimized fertilization combined with no-tillage, straw mulching and cow manure), Conservation FertilizerⅡ(the management of optimized fertilization combined with straw burying and cow manure) and Conservation FertilizerⅡ(the management with double cow manure) on agronomic characteristics, yield and economic benefit, nitrogen use efficiency of garlic, soil nitrate residue and the apparent loss of nitrogen in northern Erhai lake basin. The results indicated that:1. The soil organic matter is very abundant in the field of northern Erhai lake, the average content of organic matter reaches 56 g·kg^-1, the average content of total nitrogen is about 3.3 g·kg^-1, and it is above 4.5 g·kg^-1 in garlic planting area.2. The irrational fertilizer of garlic cause nitrogen loss in northern Erhai lake basin. 297 investigation samples showed that the N, P input of garlic is about 790 kg·ha^-1 and 154 kg·ha^-1 respectively, and about 3 times and 2.3 times respectively as high as actul uptakes of N, P.3. The reasonable nitrogen input was 345-545 kg·ha^-1 in the middle or high fertility soil of northern Erhai lake basin, which could consider to the garlic yield and environment benefit.4. Conservation FertilizationⅠcould significantly improve the soil moisture content, and the moisture content of 0^-10 cm soil was up to 10% higher than the others; Conservation Fertilizer technologyⅡcould significantly improve the soil temperature of plough layer.5. Conservation FertilizationⅠandⅡcould guarantee yield, improve nitrogen use efficiency and economic benefit. Compared with conventional fertilization treatment, The garlic yield and economic benefit of Conservation Fertilization I increased by 7.9% and 14.1% respectively; The garlic yield of Conservation FertilizerⅡreaduced by 8.5%, but the economic benefit increased by 5.7%; Nitrogen use efficiency for Conservation FertilizationⅠandⅡincreased by 20 and 11 percentage points respectively.6. Conservation FertilizationⅠandⅡcould significantly reduce the risk of nitrogen loss. Compared with conventional fertilization treatment, 0-30 cm soil nitrate residue of Conservation FertilizationⅠandⅡsignificantly reduced by 44.2% and 61.0% after garlic harvesting, and the total dissolved nitrogen loss reduced by 59.8% and 54.0% during punding period before rice planting.In conclusion, Conservation Fertilization was a good technique for Erhai lake basin, which could consider to economic and environment benefit and effectively prevent agricultural non-point pollution.