Detailed Explanation of Harmless Treatment Technology and Methods for Cow Dung
Cow dung contains 14.5% organic matter, 0.30%-0.45% nitrogen, 0.15%-0.25% phosphorus, and 0.10%-0.15% potassium, making it a valuable resource that can be used by the planting industry as a source of soil fertilizer. The organic matter and nutrient content of cow dung are the lowest among various livestock, with a fine and dense texture, high moisture content, slow decomposition, and low heat generation, making it a slow-release fertilizer.
?1. Composting.Composting technology is an important pathway for the harmless treatment and resource utilization of cow dung. Research on cow dung composting has been carried out relatively systematically in areas such as combined fermentation with other resources, selection of fermentation microbial agents, additives, fermentation temperature, humidity, and characteristics of the fermented product.
?2. Vermicomposting.Using earthworms to treat livestock and poultry waste is an ancient yet newly emerging biotechnology. Since the late 1980s, many scholars domestically and abroad have been dedicated to research on using earthworms to treat waste. Compared with naturally composted decomposed cow dung, vermicomposting treatment products have higher mineral nitrogen and available potassium than decomposed cow dung, but no significant difference in available phosphorus; microbial biomass carbon and nitrogen and enzyme activity are significantly higher than naturally decomposed cow dung; the numbers of bacteria, fungi, and actinomycetes are also higher than naturally decomposed cow dung, but with greater fluctuation.
?3. Catalytic oxidation treatment.The catalytic oxidation method is used to degrade cow dung, converting undigested and undecomposed crude fiber, crude protein, crude fat, and humic acid substances into water-soluble organic substances and amino acid-fulvic acid (A-FA). The reaction is carried out under fully enclosed conditions, with no exhaust gas, waste liquid, or waste residue discharge throughout the entire process. The water-soluble organic substances in the product include fulvic acid, amino acids, other low-molecular-weight organic acids, and sugars. The content of active functional groups such as carboxyl groups and phenolic hydroxyl groups is slightly higher than that of weathered coal and peat fulvic acid, close to soil fulvic acid, and the product has considerably high chemical activity and biological activity.
?4. Used for aquaculture.Because feed is degraded by microorganisms to a high degree within the cow's body, cow dung consumes less oxygen in water than other livestock and poultry manure. Practice has confirmed that when cow dung is applied to fish ponds, fish pond oxygen deficiency and surface gasping phenomena are fewer. When using cow dung for fish farming, fermentation is not necessary, and fresh manure works better. The frequency and amount of application should be flexibly adjusted according to weather, water color, fish growth, and surface gasping conditions. Table 1 shows the proportion of cow dung applied each month and the number of applications per month in fish ponds in southern Jiangsu. Zhang Zhibin