Effect Of Agricultural Usage Of Biogas Slurry On Yield, Quality Of Oil-seed Rape And Quality Of Soil

Biogas slurry is a kind of liquid organic fertilizer, which can be regarded as slow-release fertilizer as well as active fertilizer. It has many advantages such as long residual action of organic fertilizer, quick acting of chemical fertilizer, nutritious, lasting effect and so on. To develop ecological agriculture nowadays, we should promote to use biogas slurry rationally with safe and recycle treatment, thus to reduce the production costs and obtain comprehensive benefits such as economic, environment and other benefits.In this study, the resource utilization of biogas slurry and agricultural production were combined. Biogas slurry anaerobic fermented with pig manure of large-scale pig farms, were used as fertilizer sources instead of chemical fertilizers. The total N, P, K nutrients of biogas slurry was 1.689g/kg, where N is 1.102g/kg. It was applied to conduct filed experiment of planting oil-seed rape in Qionglai city of Sichuan province on the paddy soil. Effects of biogas slurry on growing development, yield and quality of oil-seed rape, quality of soil were investigated under different application rates of biogas slurry with water and chemical fertilizer as controls. The appropriate application rate of biogas slurry in the production of oil-seed rape and the maximum capacity of biogas slurry that soil could bear were determined, thus to provide a theoretical basis for the scientific resource utilization of biogas slurry in agricultural production. The results of this study were as follows:1. The optimum application rate of biogas slurry considering improving the yield and quality of oil-seed rapeAppropriate amount of biogas slurry application can not only help to improve yield, nutritional quality of oil-seed rape, but also improve the contents of mineral elements and reduce the contents of heavy metals in rapeseed to a certain extent. When the biogas slurry application rate was in the range of 78750kg/hm2 to 112500kg/hm2(treatment 6 to 9), the yield of rape was the highest. When the biogas slurry application rate was in the range of 78750kg/hm2 to 101250kg/hm2(treatment 6 to 8), the nutritional quality of of rape was the best. When the biogas slurry application rate was in the range of 22500kg/hm2 to 90000kg/hm2 (treatment 3 to 7), the contents of mineral elements of rapeseed stayed at a high level. When the biogas slurry application rate was in the range of 22500kg/hm2 to 90000 kg/hm2 (treatment 3 to 7), the contents of heavy metals under biogas slurry treatments were all significantly lower than that of conventional chemical fertilizer treatment. What's more, they were all in line with the corresponding limits of "Hygienic Standard for Oil seeds"(GB19641-2005). Considering the effects of biogas slurry on the yield as well as quality of oil-seed rape, this study suggests that when the biogas slurry application rate was in the range of 78750 kg/hm2 to 90000kg/hm2 (treatment 6 to 7), the yield of rape was the highest and the quality of rape was the best, the economic benefit of biogas slurry application was better.2. The optimum application rate of biogas slurry taking the quality of soil into accountAppropriate amount of biogas slurry application can improve the soil pH, thus to prevent soil acidification. When the biogas slurry application rate was in the range of 78750kg/hm2 to 101250kg/hm2(treatment 6 to 8), the contents of total nitrogen, alkali-hydrolyzable nitrogen, available phosphorus, available potassium, organic matter of soil were all significantly higher than that of conventional chemical treatment. When the biogas slurry application rate was in the range of 78750kg/hm2 to 112500kg/hm2 (treatment 6 to 9), the content of total exchangeable bases didn't have significantly difference with that of conventional chemical treatment, meanwhile, the biogas slurry application could help to improve the contents of CEC, exchangeable potassium, exchangeable sodium and exchangeable magnesium in soil. Appropriate amount of biogas slurry application could also improve the contents of mineral elements in soil, when the biogas slurry application rate was in the range of 78750kg/hm2 to 135000kg/hm2 (treatment 6 to 10), the contents of mineral elements in soil stayed at a high level. The contents of heavy metals in soil increased with the increasement of application rate of biogas slurry to varying degrees, but when the biogas slurry application rate was in the range of 22500kg/hm2 to 90000kg/hm2 (treatment 3 to 7), the contents of heavy metals in soil stayed at a low level. When the biogas slurry application rate was in the range of 78750kg/hm2 to 180000 kg/hm2 (treatment 6 to 12), the number of bacteria, actinomycetes and fungi increased, soil urease activity and invertase activity was significantly increased while catalase activity in soil weakly increased. So this study suggests that when the biogas slurry application rate was in the range of 78750kg/hm2 to 90000kg/hm2 (treatment 6 to 7), the soil fertility was high, the environmental quality of soil was better, the environmental benefit of biogas slurry application was better.To sum up, application of biogas slurry anaerobic fermented with pig manure of large-scale pig farms as fertilizer sources instead of chemical fertilizers to plant oil-seed rape on the paddy soil in Qionglai city of Sichuan province, considering the effects of biogas slurry on growing development, yield and quality of oil-seed rape as well as quality of soil, the appropriate application rate of biogas slurry in the production of oil-seed rape was in the range of 78750 kg/hm2 to 90000 kg/hm2 and the maximum capacity of biogas slurry that soil can bear was 90000 kg/hm2, when the quality of soil was better.