| With the rapid development of urbanization and economy, Chinese livestock production has been unprecedented development due to the great changes in people’s demand for food and diet. At the same time, with the increasing of livestock number and the degree of the scale, the environmental pollution was enhanced. Systematic review on nutrient flow and environmental emission characteristics of livestock system in the peri-urban area of large cities is an important basis for policy to control the scale of farming, optimize the layout of livestock production, protection of ecological environment and ensure the supply of livestock product. In Beijing, the output value of livestock production accounted for 36% of the overall agricultural production. The increasing number of livestock and change of farm type from backyard to intensive resulted in harmful effect on air, water and soil by manure nutrients and pathogenic bacteria. This study based on farm survey data collected by livestock categories (pigs, dairy, beef cattle, layer, broiler and duck) for different scale of farm, literature data and NUFER-animal model to expound based nutrient flows, nitrogen and phosphorus use efficiency and environmental loss. By selecting the 13 indicators, environmental (nitrogen use efficiency, phosphorus use efficiency, nitrogen losses, phosphorus losses, nitrogen sales and phosphorus sales), economic (feed conversion rate, cost and net income) and social performance (labor productivity, distance, mortality rate and density) of peri-urban livestock was analysed. Then, the effect of production and manure management was quantified to the environmental, economic and social performance. Lastly, extended the farm scale to regional scale, temporal and spatial variation of nutrient flow and environmental losses were analysed, and several options were explored from the survey to reduct the emission through scenario analysis. The main results are as below:(1) Nitrogen and phosphorus use efficiency (NUE and PUE) obviously difference among different farm system. At the animal level, the nitrogen use efficiency of pig, dairy, beef cattle, layer,broiler and duck was 23.0%,20.5%、10.4%、28.5、34.4%'33.2%, respectively. Phosphorus use efficiency of pig, dairy, beef cattle, layer,broiler and duck was 31.0%、25.2%、24.0%、21.5%、46.3% '44.3%, respectively. The NUE and PUE were proportional to farm size.(2) Production 1 kg of protein nitrogen in meat products, the average N losses and net profit was significantly higher than that of milk and egg products. The state of phosphorus had the opposite result. The environmental loss caused by the production of lkg product protein was inversely proportional to the farm size, while the net profit of 1kg product protein was proportional to the farm size.(3) 13 different index scores of different animal farms were different. The average scores of each index of different animal farms ranged from 30 to 70, which were in medium and high level of sustainability. The index scores of different animal farm generally increased with the increase of farm size.(4) Different animal farm management has a significant impact on the environment and economy of livestock and poultry. Farm size was positively correlated with farm income, and negatively correlated with nitrogen and phosphorus. Feed conversion rate was significant negative correlation with farm income, NUE and PUE and significantly positive correlation with N and P losses. Crude protein was also significant negative correlation with farm income, NUE and PUE. Manure management was only related to nitrogen and phosphorus losses.(5) Historical changes in nutrient flow results showed that imported feed which was one of the inputs of system nutrient flow was far greater than that of the other feeds. The increasing amount of nitrogen sales was much higher than that of nitrogen loss. The soil nitrogen accumulation was increased, while the phosphorus accumulation decreased. This is a significant characteristic of peri-urban livestock production that feed was gained mainly by external imports and manure was sales out of the farm.(6) The changes of livestock number and farm structure had a great impact on the changes in the space of the livestock production. Comparing with 1980, nitrogen loss increased rapidly in the peri-urban area, and decreased rapidly in the city center area in 2013.(7) Scenario analysis results showed that the integrated management of feed input (feed input of pig, dairy, beef cattle, layer, broiler and duck reduced 18.5%,18.0%,39.0%,32.0%,25.0% and 25.0% compared with current situation) and manure management can reduce nitrogen and phosphorus loss 47.3% and 65.5%(pig),49.6% and 77.0%(dairy),65.8% and 94.2%(beef cattle),65.7% and 84.8% (layer),54.0% and 84.4%(broiler) and 61.7% and 84.6%(duck), respectively. The mitigation potential of N and P emissions was considerably large. |
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