10 key technologies! Technical guidance on regulating livestock and poultry manure treatment to reduce nutrient loss

         In order to implement the decision-making and deployment of the Opinions of the General Office of the State Council on Accelerating the Resource Utilization of Livestock and Poultry Breeding Wastes, standardize the treatment of livestock and poultry manure, reduce nutrient losses, promote the cycle of planting and breeding, and coordinate the emission reduction of ammonia and other odors. Reduce greenhouse gas emissions in manure treatment links, improve the resource utilization level of livestock and poultry manure, and provide technical support for the green, the national animal husbandry station, together with the technical steering committee of livestock and poultry breeding waste resource utilization of the Ministry of agriculture and rural areas, puts forward the following guiding opinions.

Technical guidance on regulating livestock and poultry manure treatment to reduce nutrient loss

1. basic principles

1. Adhere to the actual development of animal husbandry. Comprehensively consider the effective supply of livestock products, the basis for the development of animal husbandry, and the requirements of environmental protection, actively and steadily promote the transformation and upgrading of manure treatment facilities and equipment, and rationally select more economical treatment technologies.

2. Adhere to the development of planting and breeding cycle. Focus on the local return of livestock and poultry manure to the field, improve and simplify the treatment facilities and equipment, promote the improvement of standardized return to the field, and reduce the loss of nutrients in the process of manure treatment and utilization.

3. Insist on refining requirements according to local conditions. All localities should fully consider the characteristics of regional resources and environment, refine the requirements of livestock and poultry manure treatment facilities and processes step by step, and actively explore technical models with local characteristics.

2. key technology

1. Low protein diet formula technology. Referring to the compound feed for piglets and growing-finishing pigs (GB/T 5915-2020) and the compound feed for laying hens and broilers (GB/T 5916-2020), under the premise of ensuring that the production performance and product quality of pigs and poultry are not affected, amino acids and enzyme preparations are reasonably added to reduce the crude protein content in the diet and improve the nitrogen utilization efficiency of the feed.

2. Optimize the manure cleaning technology of livestock house. For livestock and poultry farms using dry manure removal technology, if the frequency of manure removal in the original house is low, the frequency of manure removal can be appropriately increased by 1-2 times/day to reduce the residence time of manure and urine in the house. For livestock and poultry farms using bubble manure technology, deep pit storage or shallow pit storage technology is selected, and trench fans are configured when necessary. The daily total amount of manure produced by each fattening pig does not exceed 0.015 cubic meters.

3. Biological fermentation bed culture technology. Rice husk, sawdust, crushed straw, etc. are used as bedding for biological fermentation bed, and microbial agents are sprayed on the bedding regularly. In-situ and under-net biological fermentation beds can be used for poultry breeding. The proportion of rice husk in the bedding material shall not exceed 30%, and the thickness of the bedding material shall not be less than 40cm. The fermentation bed shall be turned regularly, and the number of turning shall be at least once a week to ensure that the bedding material and manure are fully mixed. In areas with large evaporation in the north, in-situ biological fermentation beds can be used for sheep breeding. The thickness of bedding is not less than 15cm, and raking is not required. The interval between dung removal is not more than 40 days in winter and 60 days in winter.

4. The enclosure exhaust air purification technology. For closed barns with mechanical ventilation, wet purification facilities such as spray device and wet curtain are installed outside the exhaust fan, and the liquid with weak acid or oxidant such as sodium hypochlorite is sprayed for filtration, wherein the pH value of the acidic washing liquid is controlled below 6; Or the air discharged from the barn is filtered through biomass packing, which is mainly made of wood chips, straw, etc. Existing research shows that the use of air purification technology can reduce the intensity of exhaust air odor by more than 50%.

5. Liquid manure cover storage technology. Including fixed cover storage and floating cover storage. Fixed cover refers to the capping or coating of liquid manure storage facilities, which should be equipped with gas vents or gas recovery and treatment devices to prevent the accumulation of flammable gases. Floating cover refers to the use of geometric plastic cover sheets, vermiculite and other floatable objects, which are suitable for liquid manure storage facilities with large surface area in areas with less precipitation.

6. Liquid manure acidification storage technology. By adding an acidifier to reduce the pH of the liquid manure, the nitrogen is retained in the manure in the form of a more stable ammonium salt. Commonly used acidifiers include sulfuric acid, superphosphate, etc. Adjust the pH to 5.5-6.5. The acidified liquid manure needs to be stored and fermented. Existing studies have shown that when the pH value of the manure is less than 6, the nitrogen loss can be reduced by more than 50%.

7. Solid manure closed composting technology. According to the water content of solid manure, add sawdust, broken straw and other materials appropriately to ensure pile-up. Select a suitable location for closed anaerobic fermentation, and the composting period should be no less than 60 days. When composting, it is appropriate to choose sunny, high-lying and relatively flat open space. The bottom should be impermeable, and the surrounding should be sealed with plastic film or covered with soil, and rainproof treatment should be done at the same time.

8. Solid manure closed composting technology. Includes reactor compost and film compost. The reactor compost fermentation time is not less than 7 days, and the odor generated during the fermentation process is uniformly purified. Film compost should be hardened on the site, the top of the pile body is covered with expanded polytetrafluoroethylene film, the odor is trapped in the pile body, the bottom is regularly ventilated, and the fermentation time is not less than 14 days.

9. Composting bio-based deodorization technology. In the strip-type and trough-type aerobic composting closed workshops, the air is sent to the bottom of the bio-based filter bed through the exhaust fan, and the exhaust air is purified through the processes of moisture film absorption and microbial action. Bio-based filter beds are generally made of biomass materials such as compost products and sawdust, with a water content of 50%-65%, and nitrogen recovery is realized while purifying the air. Existing research shows that the technology can reduce the intensity of odor emissions by more than 90%.

10. Liquid manure overlaid application techniques. After the liquid manure is applied to the soil surface by means of spraying, pouring, flushing, leaching, strip application and drip irrigation, it is advisable to plow into the soil in time to reduce the residence time of manure on the soil surface and the contact area with air. Liquid manure can also be applied 3-35cm below the soil surface by injection and other fertilization methods.

3. considerations

1. Do a good job of reducing emissions at the source. Guide farmers to reduce water consumption, strictly implement the standards for the use of feed additives, standardize the use of veterinary antibacterial drugs and disinfectants, and reduce the pressure of rear-end manure treatment.

2. Improve the level of treatment. The treatment shall be carried out in accordance with the Technical Specification for Harmless Treatment of Livestock and Poultry Manure (GB/T 36195-2018), and the scale of storage and treatment facilities shall be determined according to local conditions, so that the scale of facilities and the interval between returning to the field can be matched, the normal operation of facilities shall be ensured in strict accordance with the operation procedures, and regular maintenance and management shall be carried out to ensure safe and effective operation.

3. Strengthen the use of manure. Strengthen the detection of livestock and poultry manure, pay attention to summarize the number, time and method of application of livestock and poultry manure in different regions and crops, and avoid the impact of excessive application and improper application on plant growth.