Environmental pollution in livestock and poultry breeding and the utilization of manure resources

The feces produced by livestock and poultry breeding often contain strong odors and have low utilization efficiency. Many farms discharge them untreated into surrounding water channels and land, causing the surrounding environment to suffer from odors and pollution. Especially in large livestock farms, improper manure treatment often leads to significant environmental pollution and significant waste of resources. This article focuses on the resource utilization path of livestock and poultry manure to reduce environmental pollution and promote sustainable agricultural development.
01
Difficulties in the End Use of Livestock and Poultry Manure
（1） Improper treatment of feces can easily cause environmental pollution
1. Air pollution
Biocomposting and biogas fermentation are effective methods for treating animal manure, which are in line with sustainable circular agriculture models and widely implemented in animal husbandry. However, if these methods are not applied properly, they may lead to energy waste and environmental pollution.
Ammonia and greenhouse gases (such as methane and nitrous oxide) may be released during the fecal treatment process. Ammonia is a precursor to PM2.5, and if released in large quantities, it may cause haze problems. Meanwhile, the release of methane and nitrous oxide will exacerbate the greenhouse effect, leading to a series of environmental crises such as global warming and ecosystem degradation. Many livestock and poultry farms have limited scale, and some farms have problems with capital turnover. The technology and management level of small-scale farms are insufficient, and the treatment methods are extensive. The fermentation and maturation are incomplete, and they are directly returned to the fields, resulting in gas pollution (ammonia, methane, nitrous oxide).

2. Heavy metal pollution
In addition to gas emissions, heavy metal pollution is also an environmental hazard that cannot be ignored. In animal husbandry, in order to accelerate the growth rate of animals, high levels of heavy metal elements such as copper (Cu), zinc (Zn), arsenic (As), etc. are often added to animal feed. These elements are the main sources of heavy metal pollution in animal manure.
Studies have shown that the levels of copper, zinc, arsenic, and other elements in the feces produced by large-scale farms are much higher than those in small-scale household farms. Livestock have difficulty fully absorbing heavy metal additives contained in feed and can only be discharged into the environment through feces, which can lead to soil pollution and enter the human body through the food chain, endangering human health. This should be taken seriously.
3. Water pollution
Harmful substances, parasite eggs, bacteria and viruses in manure can also cause water pollution when they flow into water sources. Livestock and poultry manure pollution is the main source of water pollution. The pollution caused by ineffective prevention and control of feces not only endangers aquatic animals, but also leads to parasitic infections, diseases, and even death; Aquatic plants will proliferate wildly in environments rich in nitrogen and phosphorus, causing eutrophication, algal blooms, and even altering the structure of the aquatic food chain, resulting in reduced food supply for fish; The oxygen content in the water decreases, and aquatic animals die due to hypoxia.
（2） Difficulties in utilizing manure
As a major animal husbandry country, with the expansion of livestock and poultry breeding scale, the utilization of organic manure has become a major challenge in China.
① The Organic Fertilizer market lacks strict standards and regulation, and the market is chaotic.
② The technological level is backward, the core technology is insufficient, and the fertilizer efficiency is not as intuitive and fast as chemical fertilizers; Farmers tend to use fertilizers because they are convenient and effective; Although biogas slurry and some organic fertilizers have long-lasting fertilizer effects, their effects are not significant and lack competitiveness.

02
The significance of utilizing manure resources
（1） Reduce environmental pollution
During the process of livestock and poultry breeding, a large amount of manure is generated, which contains a large amount of organic matter and harmful substances. If directly discharged into the environment, it will cause serious pollution to the surrounding environment. Through the resource utilization of manure, these manure can be converted into organic fertilizers for fertilization in farmland, thereby reducing the use of chemical fertilizers and minimizing the impact of agricultural production on the environment.
（2） Promote sustainable development of agriculture
Livestock and poultry waste is an excellent source of organic fertilizer, rich in essential nutrients such as nitrogen, phosphorus, potassium, as well as trace elements and organic matter. These substances can enhance soil enzyme activity, alter soil microbial structure and abundance. Compared with chemical fertilizers, cow manure can significantly increase the microbial biomass carbon, nitrogen, and catalase activity in soil; Pig manure can significantly increase the activity of soil urease and alkaline phosphatase; Sheep manure enhances the activity of sucrase. Promote the growth and development of crops, improve their quality and yield. Meanwhile, the use of organic fertilizers can also improve the quality and taste of agricultural products, meeting people's demand for green and organic food.
（3） Promote sustainable development of rural economy
The development of livestock and poultry breeding industry requires a large amount of feed and energy, and the prices of these resources continue to rise, bringing great pressure to the breeding industry. By utilizing manure resources and adopting a combination of planting and breeding methods, the recycling and reuse of waste materials can be achieved, optimizing resource utilization efficiency, reducing agricultural production costs, and enhancing farmers' economic benefits.