Abstract :
[en] Nowadays, scale-up intensive pig farming can increase profitability, but it also exacerbates environmental pollution such as the contamination caused by the disordered discharge of manure and sewage. China, as the largest pig-breeding country globally, dominates 48.4% of worldwide pork output. Pig rearing is shifting from free-range to specialization and mass farming, generating a large amount of manure and sewage simultaneously, with 4.37 billion tons accounting for 76.8% of total livestock waste discharge. Pollution caused by pig breeding has become the priority issue to be resolved. Manure & sewage management (MSM) is critical to mitigate environmental pressure and realize resource recycling. However, applications of MSM in pig farming are multitudinous, due to the complicated process sections, diverse methods and heterogeneity of farmers' characteristics and behaviors. In addition, this more intensive breeding structure is accompanied by the integrated generation of pig waste. The match is disrupted between the original MSM mode and the corresponding farmland. These issues cause the separation of cropping and breeding, hinder the transition from traditional breeding to an ecological and sustainable pig industry. Appropriate MSM mode with optimized system contributes to the mitigation of environmental pressure, integration and efficient use of resources, and provides additional financial success because of the circular economy, further achieving green scientific and sustainable pig breeding.
This study conducted a comprehensive perception of pig MSM application in Hebei province, China, based on a field survey. Collect 614 questionnaires involving information on pig farms, MSM practices performed, farmers’ behaviors, perceptions and environmental awareness, and farmers’ perceptions of government regulations and policies. It is representative of a region with a well-developed pig sector and can provide useful references for other regions and developing countries practicing breeding with cropland.
To begin with, this study conducted a systematic overall review of current pig MSM operational practices. Empirically categorize typical MSM modes in pig farming, distinguish and identify the characteristics of corresponding modes by data-driven typology, clustering analysis, from a scientific and statistical perspective. Five mainstream MSM modes were obtained to simplify the high diversity of MSM strategies, with highlighted advantages and performances. Traditional simple mode (TSM) is based on simple processing methods and convenient access. Mixed processing mode (MPM) is a labor-intensive saving mode with the lowest mechanization degree. Semi-biogas mode (SBM) is guided by anaerobic digestion with incompleted utilization. Professional processing with simple utilization mode (PPSUM) has comprehensive treatments with unified field application. Professional processing with full utilization mode (PPFUM) is an integrated mode that well-performing in processing and resource multi-utilization. Mode classification enhances the efficiency of MSM and contributes to the ease of administrative convenience by the government.
Secondly, the heterogeneity of farmers' characteristics and behaviors towards five MSM modes was identified by multiple independent sample test and multinomial logistic model, to reveal the underlying determinants that might affect individual decision-making. Applicability of the respective mode was reflected in the synthesis deliberation, involving farming structure, land, farmers’ characteristics and subjective awareness. Farmers’ education level and pro-environmental perception significantly promoted the adoption of technology-intensive modes. Scale upgrading had a positive effect on mechanization and diversified strategies application. Land restricted the extension of modes based on field returning. Understanding these driving forces contributes to the design of an optimal and tailor-made MSM scheme with greater adaptability, meanwhile, providing credible experience and qualification to individual pig farms on appropriate mode selection to enhance effective MSM in pig farming.
Thirdly, considering the trend towards more intensive breeding, the possibility of a centralized MSM pattern is proposed to relieve environmental pressure, increase resource recovery efficiency and rebuild the coupling effect of cropping and breeding. A comprehensive comparative evaluation between individual and traditional mode (ITM) at the household level and centralized bio-energy mode (CBM) at the regional scale was conducted by life cycle assessment (LCA) and life cycle cost analysis (LCC), involving dual objectives of economy and environment. CBM appeared to be a better alternative in global warming, terrestrial acidification and marine eutrophication, with significant reductions of 49.49%, 6.8% and 4.67% respectively compared with ITM. Moreover, it demonstrated a substantial profit of 48.5 CNY from handling 1 ton of pig waste. Furthermore, both environmental and economic performance could be improved by scale expansion and transport optimization, with an optimal collection radius of less than 31.45 km, and a decrease in marginal cost in the range of 7.2-16.82 CNY. The applicability and feasibility were further explored for the mode implementation in the other seven regions in China.
Lastly, explore underlying determinants affecting farmers' decision-making on scientific and comprehensive MSM practices to cater to the goals of ecologically sustainable farming. Establish a synthetical stylized framework that matches a wide array of theoretical and empirical information, with land factors, resource endowments, policy rationality and individual characteristics. Use ologit regression model, the effect and intensity of several implicit factors were analyzed from the perspective of farm scales. Statistical results identified that strengthening land transfer and integration contributes to the adoption of combined MSM practices, enhancing technology, labor and economy endowments supports the diversity of technological applications. Additionally, farmers’ environmental perception and policy rationality also reported positive effects on enhancing waste resource utilization level and further forming the green sustainable pig industry.
In general, findings in this study are expected to mitigate environmental hazards from pig-intensive breeding, achieve maximum nutrient recycling of pig waste, and enhance MSM effectiveness and sustainability. It contributes to providing pig farmers with persuasive references on appropriate MSM mode selection, theoretical supports for the regional pattern replication in response to the updated breeding restructuring, implications for government policy-making to optimize overall benefits from environmental, economic and social impacts. In order to achieve the modernization, ecologicalization and sustainability of MSM and pig industry.
