Biogas slurry is the residual liquid after anaerobic fermentation, which is still a high-concentration organic wastewater. If it is directly discharged into the environment without reasonable treatment and utilization, it will cause secondary pollution.
Biogas slurry contains a large number of nutrients, mainly including abundant nitrogen (0.03%~0.08%), phosphorus (0.02%~0.07%), potassium (0.05%~1.40%) and other macronutrients, calcium, copper, iron, zinc, manganese and other medium and trace nutrients, as well as rich amino acids, B vitamins, various hydrolases, certain plant hormones and substances or factors that have inhibitory effects on pests and diseases. Because of this, the role of biogas slurry can be divided into biogas slurry fertilizer, biogas slurry seed soaking, foliar spraying, biogas slurry fish farming, etc.
Biogas slurry fertilizer. Biogas slurry cultivation is the most widely used. Biogas slurry can be used as liquid fertilizer for the cultivation of field crops, vegetables, fruit trees, forage, etc. When using biogas slurry fertilizer, it can be applied for irrigation or as foliar fertilizer. When applying the biogas slurry, it can be directly mixed with irrigation water in a certain proportion for irrigation, or it can be directly combined with drip irrigation or infiltration irrigation. As a liquid quick-acting fertilizer, biogas slurry has a good yield-increasing effect when applied as topdressing.
Biogas slurry seed soaking. It mainly uses the bioactive substances and quick-acting nutrients contained in the biogas slurry to pre-treat the seeds, which can stimulate and activate the nutrients in the seeds, promote cell division and growth in the seeds, and provide the seeds with the nutrients required for germination and seedling growth. At the same time, it can also eliminate pathogens and bacteria carried by the seeds. Therefore, after the seeds are soaked in biogas slurry, the germination rate of the seeds is high, the buds are uniform, the seedlings are strong, the root system is well-developed, and the growth is vigorous. In addition, biogas slurry can enhance the drought resistance, disease resistance and stress resistance of the seedlings.
Biogas slurry foliar spraying. The metabolites of anaerobic microorganisms contained in the biogas slurry, especially trace elements such as copper, iron, zinc, manganese, and a variety of biologically active substances, can be quickly absorbed by the plants, effectively regulate crop growth metabolism, and provide nutrition for crops; the biogas slurry also contains a variety of microorganisms, beneficial bacteria, various hydrolases, certain plant hormones and secreted active substances, which have a certain inhibitory and killing effect on many harmful pathogens and insect eggs of plants, and also have an inhibitory effect on some plant diseases and insect pests.
