Modeling farm nutrient flows in the North China Plain to reduce nutrient losses

Abstract

Years of poor nutrient management practices in the agriculture industry in the North China Plain have led to large losses of nutrients to the environment, causing severe ecological consequences. Analyzing farm nutrient flows is urgently needed in order to reduce nutrient losses. A farm-level nutrient flow model was developed in this study based on the NUFER (NUtrient flows in Food chains, Environment and Resources use) model, and was used to analyze nitrogen (N) and phosphorus (P) flows, use efficiencies, and losses for nine representative farm types in the North China Plain. Data from 401 farms were evaluated for the years 2012–2015. The analysis showed that mixed farms were more efficient in nutrient utilization than crop-based or landless livestock farms. The efficiencies of N and P used in crop production were highest for mixed dairy farms, reaching 67% for N and 68% for P. Consistently, mixed dairy farms had the lowest N and P surpluses and losses in crop production. Mixed swine farms were 5 and 9% higher in N and P efficiency in livestock production than landless swine farms, respectively. Losses of N and P from the animal manure management chain were 20–42% lower for mixed swine and 69–78% lower for mixed poultry farms than for landless farms of the same animal type. This is at least partially due to more frequent manure removal. Integrated crop-livestock production using livestock wastes as crop fertilizer was shown to be the most sustainable model in nutrient use for the agriculture industry in the North China Plain.