Mitigating environmental impacts of milk production via integrated maize silage planting and dairy cow breeding system: A case study in China

Abstract Environmental impacts of milk production are depending on the production efficiency of livestock and cropland. A mode of integrated maize silage planting and dairy breeding system (IPBS) has been widely promoted in China, as a promising way to recycle manure, reduce chemical fertilizer consumption and improve soil quality. However, quantitative environmental impacts and mitigation potential of this system remains unclear. In this study, based on life cycle assessment (LCA), environmental performance of non-IPBS and IPBS were compared: non-IPBS only involved dairy cow breeding, whereas maize silage planting was incorporated in IPBS. Results indicated that, although 60% of the surveyed dairy farms adopted IPBS, the self-sufficiency rate of maize silage was 57%. Compared with non-IPBS, IPBS had apparent potential in reducing global warming potential (-14%), acidification potential (-10%), eutrophication potential (-18%), non-renewable energy use (-10%), water use (-8%) and land use (-13%). It is estimated that, in China, 81% of dairy farms could adopt IPBS, resulting in a reduction of approximately 21% in greenhouse gas (GHG) emissions to compared with current situation, but the premise is that 2.0 million ha cropland should be applied for maize silage cultivation. Interestingly, environmental performance of IPBS was affected by the self-sufficiency rate of maize silage and restricted by milk yield and maize silage yield. Thus, mitigation of environmental impacts of milk production could be realized by combining a short-term strategy of increasing maize silage planting area in dairy farms and a long-term plan for technological improvements in the yield of crop and milk.