Livestock and poultry manure is an ideal kind of high-efficiency bio-organic fertilizer in the agricultural production process. Appropriate application of livestock manure can improve soil, cultivate soil fertility and prevent soil degradation. However, the direct application would cause environmental pollution and a decline in agricultural product quality. What’s worse, for those towns, factories, schools, and other surrounding areas with dense populations, a large amount of manure produced by intensive and large-scale livestock farms would not only cause serious pollution but also bring disease spreading easily without proper treatment.

Hazards of Unfermented Livestock Manure

▲ Diseases and insect pests infection: the feces contain a good deal of microorganisms harmful to health, like colon bacillus and threadworm, which may cause the transmission of diseases and insect pests after direct manure fertilization, make plants sick easily, pollute the environment and also produce an adverse effect for human health.

▲ Burning seedlings: once achieving fermentation conditions, unfermented manure in soil contains active microorganisms, and the heat produced during the fermentation process would severely affect plant growth or produce the phenomenon of burning seedlings.

▲ Poison gas harm: manure would produce sulfur dioxide and ammonia gas which are noxious gas for crops and the atmospheric environment.

▲ Oxygen-poor soil: organic matter would consume much of the oxygen from the soil during the process of decomposition.

▲ Slow fertilizer efficiency: the nutrients in unfermented manure are slow-release fertilizers, which cannot be absorbed and used directly by plants.

▲ Environment contamination: after all the rain and wind, the fertilizer efficiency of manure would be washed away, polluting rivers and soil.

▲ Inconvenient transportation: livestock and poultry manure without treatment have large size and low effectiveness, which is inconvenient for transportation and practical application.

Main Factors Affecting Manure Composting

◆ Carbon-nitrogen ratio: among the various elements required by microbiological decomposition, carbon, and nitrogen are the most important parts. The ratio of carbon to nitrogen is related to the temperature of composting. If the carbon-nitrogen ratio is too high, too much carbon would lead to a shortage of nitrogen raw material, and the growth of bacteria and other microorganisms would be limited, the decomposition speed of organic matter would be slow, and finally composting and fermentation process would be long. In the meantime, it would make the finished compost fertilizer with a high carbon-nitrogen ratio, which would capture Nitrogen in the soil, affecting crop growth. But if the ratio is too low, especially lower than 20:1, carbon available for consumption is not enough while nitrogen nourishment is relatively surplus, easy to volatilize, lowering fertilizer efficiency. In order to make balance the microbial nutrition involved in organic matter decomposition, the composting carbon-nitrogen ratio should satisfy the best value of 25-35:1. It is common to use raw materials with high carbon content (like straw) to adjust the ratio of carbon and nitrogen.

◆ Moisture content: the best moisture content of manure composting is usually 50%-60%. If lower than 30%, it would have a strong impact on the life activities of microorganisms; if too high, moisture would squeeze out air and reduce the composting speed, producing odor and nutrient leaching. Composting material’s water content is also closely related to its ventilation capacity and structural strength. The solid-liquid separator is able to adjust the water content of raw materials, reducing manure moisture to a great extent.

◆ Temperature: for composting, the temperature is an important factor for the smooth progress of composting and fermentation because it has a significant role in microorganisms’ growth. It is generally believed that the degradation efficiency of organic matter by high-temperature bacteria is higher than that of medium-temperature bacteria. In the early days of compost, the temperature of piles is