Manure as waste and food as feed: Environmental challenges on Chinese dairy farms

Rapid intensification and decoupling of animal and crop production have contributed to high nutrient losses to the environment from Chinese dairy farms and increasing food–feed competition. This study therefore aimed to understand nutrient management and food–feed competition on Chinese dairy farms. We used bottom-up data from a farm survey amongst 48 dairy farms in Henan, north-central China, between October and December 2020. Herd sizes ranged from 115 to 4289 heads, and 52% of the farms had no cropland or grassland. Farm characteristics were determined to quantify nitrogen and phosphorus flows on dairy farms. Subsequently, nutrient use efficiencies and human-edible protein conversion ratios (HePCR) were calculated and compared amongst farm typologies. We found that Chinese dairy farms largely rely on imported feed and are decoupled from crop production. On-farm croplands play a minor role in feed supply but are overloaded with cattle manure. Average nitrogen and phosphorus use efficiencies at farm level were 20% and 27%, respectively. The HePCR varied from 1.0 to 3.5, with an average of 2.3, indicating that food–feed competition commonly occurs. Farms with higher milk yields and moderate concentrate use performed better in nutrient use efficiencies and HePCR. This inefficient utilisation of nutrients highlights the urgency for developing farm-level guidelines of nutrient management that acknowledge farm differences. Our findings provide insights from both manure- and feed-management perspectives, which could help policy makers to support dairy farms to become more environmentally friendly and contribute to a circular food system.