Matching livestock manure with suitable bioconversion strategies for efficient nutrient upcycling in China

Abstract

Manure recycling is a priority in maintaining nutrient cycles within safe and just Earth System Boundaries. However, how to upcycle manure nutrients for higher bioeconomic benefits remains unclear, largely due to insufficient attention to matching livestock species with suitable manure bioconversion strategies. Here we proposed a suitable match between specific livestock manure and feed-first or fertilizer-first bioconversion strategies based on nutrient upcycling potential and economic benefit, through bioconversion experiment, field investigations and data compilation. Thereafter, we conducted a spatially explicit simulation to show the benefits of implementing this efficient solution in China. We found that matching monogastric livestock manure with feed-first bioconversion can increase N upcycling potential by 20 %∼40 % while raising net income by 1.8–4 folds, compared to fertilizer-first bioconversion. In contrast, treating ruminant manure with fertilizer-first bioconversion can increase N upcycling potential by 5 %∼14 % and reduce economic costs by >80 % relative to feed-first bioconversion. This difference arises because monogastric livestock manure contain higher levels of proteins and carbohydrates whereas ruminant manure exhibit lower concentrations. Implementing this efficient-match manure recycling solution in China could reduce nitrogen loss by 48.6 %, save 26.8 % of phosphate consumption, and double economic benefits, compared to current manure recycling practice in 2021. The findings highlight the importance of tailoring bioconversion strategies to distinct nutrient composition of manure, and offer a novel technological pathway to enhance nutrient upcycling efficiency.