Nitrogen allocation and recycling in peri-urban mixed crop\u2013livestock farms in Ethiopia

Abstract

Mixed crop–livestock (MC–LS) farms are assumed to be more environmental friendly than specialized livestock systems, due to their better options for internal nutrient recycling. However, there are large differences among MC–LS farms in nutrient allocation and recycling. Here, we posit that the relative allocation of nitrogen to crop and livestock compartments, expressed as crop–livestock ratio (CLS), determines the performance of MC–LS farms. Among 300 urban and peri-urban farms studied in 2014, 42 MC–LS farms (Addis Ababa: 20; Jimma: 22) were re-interviewed in 2016, using MonQIt (monitoring tool) questionnaire. The performances of these farms were evaluated using partial nitrogen balance (PNB), N use efficiency (NUE), N recycling index and net farm income (NFI). CLS was negatively related to N input, PNB and NFI. Livestock oriented MC–LS farms had 4–5 times higher N input and 7 times higher PNB than crop oriented MC–LS farms, because they had 2–4 times higher NFI and purchased more external N input. This indicated that N allocation has significant environmental and economic implications. Sensitivity analyses suggested that NUE at farm system level can be improved by 20–25% and N recycling (NR) by 10–20% over the current condition. In conclusion, MC–LS farms are diverse, and much of the diversity can be captured by the CLS indicator. NUE and NR of peri-urban MC–LS farms in Ethiopia can be significantly improved through NUE enhancing measures: targeted exchange of crop residues and manure between crop and livestock activities within and between farms and improving animal NUE through breeding and precision feeding.