| With the significantly rapid development of the intensive livestock farm, the increased amount of manure production can cause environmental problems. It is urgent to rationally use these livestock manure resources. Optimized manure application could avoid the environment pollution and appeal to the rapid development of resource conservation and recycling industry. It is very important to know the amount of manure generation and spatial distribution from the intensive livestock breeding, and to constantly improve the measurements of manure nutrient management at the aim of environment friendly in order to achieve the development of sustainable intensive livestock production. In this study, the amount of livestock manure and nutrients generation was calculated by the related excretion coefficient and livestock numbers from the statistical yearbook. Meanwhile, spatial distribution of manure and nutrient generation was identified by GIS map. And combined with current main mode of manure management, the potential of organic wastes used as composting feedstock was analyzed by using the theoretical assumed value. Meanwhile, the status and existed problems of manure management in typical high livestock density regions were analyzed by farmer questionares interviewing from crop system and livestock farm combined with literature reviews. In addition, available manure nutrient supply and fertilizer substituted with manure were carried out in the typical regions with high livestock density, Beijing was studied by scenario analysis as a sample. Finally, taking an example of manure phosphorous utilization, the ’landbank’ of intensive livestock regions for recieving manure application was calculated using data of GIS map. And from the environmental friendly perspective, it should determine the change of ’landbank’ for manure application by estimating the amount of livestock manure generation in2030, and regional soil Olsen-P dynamic influenced by different mode of manure amangement in2030. The main results were as follows:1. The disposal of organic wastes (OW), i.e. crop residue, livestock manure, municipal organic wastes (MOW) and municipal domestic sludges (MDS) into the environment lead to water and land pollution and mean the waste for plant growth. Composting is the optimum choice to recycle these wastes. In this study the annual production of organic wastes and potential nutrient resources were estimated using coefficients of crop and livestock excretion and related national statistical data by official documents in2010. As the dominant wastes, the amounts of manure,50%of total OW (dry weight basis), and crop residue,45%of total OW (dry weight basis), were696megatonne (Mt) and768Mt, respectively, as estimated by statistical analysis models. The amounts of C, N, P and K in OW were555.3,20.1,4.2and21.9Mt, respectively. However, only26%of crop residue,25%of manure,2%of MOW and48%of MDS were potentially re-utilized as compost feedstock, which contributed to135.4Mt C,5.0Mt N,1.1Mt P and5.2Mt K to the nutrient pool for crop production. Compared to the current proportion of compost in manure market of China, it is necessary to strengthen the composting production in the region with high manure load to increase recycling of organic waste.2. Although the trend is the development of intensive livestock farming in China, the difference of mechanization level in this process of developing intensive livestock farming will limit manure transportation and application. The manure management methods in different regions of livestock and poultry breeding were significantly different. In Beijing, the manure cleaning method for intentsive livestock farm was98%of the faeces removal (’Ganqingfen’in Chinese). While,76%of solid manure was stored with the outdoor and open air. It easily cause the runoff or leaching losses for manure nutrients in the rainday because of bare ground.64%of solid manure from intensive livestock farm were to sell directly and to apply to field directly in Beijing.90%of liquid manure should be discarded and not be recycled. For rural household manure management,14%and67%of solid manure treated by compost and biogas was in Beijing and Jiangsu, respectively. From the point of view of composting process,36%of composting enterprises was windrow composting system.74%of composting enterprises was mechanical turning, and64%of composting enterprises was15-30days for the finished composting fermentation period. High porprotion of C, N losses was existed in the chicken, pig, cattle manure composting. In addition, the range of C and N loss in the composting was53.8-54.7%and16.3-54.3%, respectively.3. In this study, considering the current status of livestock farming and arable land area in Beijing suburbs, the current situation of organic waste resources in livestock farming and its substituting potential for chemical fertilizer were estimated through livestock farm survey, the collection of livestock excretion coefficients and crop nutrients demand through literature and related statistical data. The results indicated that total amounts of N, P, K contained in solid manure and liquid manure production were58.7×103t N,21.3×103t P,29.8×103t K, which included43.1×103t N,20.3×103t P and19.7×103t K in solid manure, respectively. Total amount of N, P, K contained in solid manure and liquid manure could be satisfied with99.3%,185.2%and62.7%of the total crop requirement of N, P, K in Beijing in2011, especially the amount of generated manure P has exceeded total crop P requirement in most districts of Beijing. Moreover, cereal straw returned to soil could bring equivalent to11.0×103t N,1.6×103t P, and15.0×103t K to arable land. In the scenario analysis, the allowable amount of NPK nutrients in livestock manure to be applied to arable land were only18.3×103t N,9.9×103t P, and10.3×103t K, respectively, based on P balance method, if considering cereal straw incorporation. Additional29.8×103t N and22.2×103t K were needed to be supplied with chemical fertilizers to meet crop demand. P surplus sourced from organic waste obligated the solid manure to be composted and transported to the neighbor regions with inadequate P supply. Total N, P, K nutrients contained in composted solid manure decreased by23%,11%and12%after aerobic composting, and the transportation of commercial composted solid manure exported out of Beijing will further reduce N and P load in arable land and consequently reduce the risk of environmental pollution.4. Rapid growth in the intensive peri-urban livestock farming has led to excessive manure P load in urban regions of China, with increasing risk in watercourses eutrophication. It is urgently to assess the potential’landbank’ available to receive the generated manure considering environmental protection. In this study, the potential distribution of manure P to arable land in Beijing through estimating soil testing P changes with P accumulation, excluding the arable land with the slope>25°, and water protection zones. The influences of soil testing P changes related to environmental risk on potential utilization of manure phosphorus were investigated under different scenarios on manure P management and proportion of cereal crop planting. Results showed that current generated manure has resulted in high P surplus, and the average manure P load rate to arable land was53kg P ha-1, with11%of arable land was unsuitable for continuous P application due to high soil P levels which exceeded P environmental risk threshold. Scenario analysis results suggested that, increasing the proportion of manure applied to cereal fields reduced the annual P surplus, which in turn alleviated the over accumulation of P in orchard and vegetable fields. The annual total manure P excretion was expected to increase to30.8Gg in2030, and soil Olsen-P level were increased to54.6,106.1and131.7mg kg-1in cereal, orchard and vegetable land, respectively. However, the balanced P managing approach could maintain the soil Olsen-P in much lower level, i.e.24.3,22.0and27.3mg kg-1in cereal, orchard and vegetable land. Applying manure to cereal field with relatively low Olsen-P level, and exporting surplus manure out of the peri-urban regions are regarded as the key ways to minimize environmental P risk.5. From a policy perspective, important suggestions were used in the optimized utilization of manure nutrient resources and minimlization of the environmental phosphorus risk including:Using balanced feed management to reduce nutrient phosphorus excretion; Adopting reasonable manure cleaning processing and solid-liquid separation process to reduce wastewater phosphorus emissions; Increasing the collection rate of solid manure phosphorus; Reducing manure volume and getting convenient transportation of manure by composting in order to decrease regional phosphorus load; Energy supply and reducing the N, P loss by biogas processing; When applying manure, to maintain the reasonable proportion and rational amount of manure and chemical P input in order to reduce the soil phosphorus accumulation and phosphorus losses in the process of leaching and runoff. |
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