Effects Of Biogas Fertilizers On The Yield, Quality Of The Vegetables And Environment

Raising re-use efficiency of agricultural waste resource and reducing the environmental pollution are the key of agricultural development. Biogas fertilizer is a kind of quality organic fertilizer which contains rich nutrients. But in recent years over-use biogas fertilizer may not cause economic losses, but cause environmental problems. In order to found the rational application of biogas fertilizer on vegetable cultivation, together with double win of economic benefit and environment of biogas. In order to study the effect of biogas fertilizer on the yield, quality of pakchoi and tomato, and soil environment, a field experiment with6treatments was conducted in Greenhouse at Liuminyin village, Daxing District, Beijing. Meanwhile, the method was used to study the effects of irrigation and biogas residue application on yield and quality of pumpkin, distribution of soil Nmin, and the result of N2O emissions and nitrogen leaching. The results were as follows:1. The crop were obviously improve by the fertilization inputs, but they didn’t have a liner relationship. The results showed that the yield of crop had a linear relationship with the applied nitrogen rate when it was lower than193kg N/hm2and273kg N/hm2. The biogas nitrogen per kilogram can increase the pakchoi dry weight of1.8kg and the tomato weight of66kg under this condition. But the pakchoi and tomato yield doesn’t increase anymore when the N input higher than193kg N/hm2and273kg N/hm2. The appropriate biogas manure application can increase soluble sugar of tomato and effectively reduce the total acidity.2. The nitrate content and soil residue Nmin was increased with the increased N rate, but, by contrast, the Vitamin-C content was decreased. Biogas fertilizer rational application can obtain the best sugar acid ratio of tomato and pumpkin. Higher soil residue Nmin and lower nitrogen use efficiency were found in the higher N input treatments. So, the reasonable application of biogas fertilizer can improve nitrogen use efficiency, reduce soil residue Nmin and increase the vegetable quality.3. The abuse application of biogas residues lead to the residual of soil Nmin、P、 K in0-30cm soils. The content of soil Nmin increased7folds than that in normal fertilization condition, the soil P reached26.18-38.06mg/kg while the soil K reached62.14-70.84mg/kg, all of which induced the leach of soil nutrition and environmental pollution under heavy rainy or unproper irrigation conditions. The leaching of N was decreased by6.14kg/hm2when treated with normal and amended fertilization management under the same use of fertilizers. It is thus clear that unreasonable irrigation is one of the important factors to cause soil N leaching loss. The significant temporal variability of N2O flux from all treatments was observed in different growing stages of cucumber. An excess of biogas fertilizer investment will increase N2O emission.