Nitrogen dynamics in agroforestry systems. A review

Agroforestry is an agricultural diversification practice that purposefully grows trees together with crops and/or animals. Nitrogen (N) plays a pivotal role in the sustainability and productivity of these systems. In this study, we synthesize our current understanding data availability N dynamics agroforestry systems, providing first comprehensive synthesis on major pathways agroforests. We review five categories pools fluxes: input, internal cycle, sequestration, loss, output. Within categories, compile from worldwide measurements input gaseous emissions. The inputs among systems are N2 fixation through leguminous (global average: 240 kg ha–1 yr–1), organic amendments inorganic fertilizers (36 and, possibly, undocumented deposition. Various identified cycles: direct transfer fixed tree to crop, mineralization matter originating trees, pumping up subsoil by roots, ammonia captured trees. practices almost consistently show reductions via soil erosion, runoff, leaching. release as nitrous oxide (N2O) (~4.7 N2O–N yr–1) nitric (NO). While N2O emissions either higher (improved fallows) or lower (riparian buffers) comparison monocropping, NO similar monocropping. sequestration rates (98–154 ha−1 yr−1) three times than biomass (36–43 yr−1). Since can increase crop yield content crops, translates into output Studies required accurately quantify sub-components fluxes identify mitigation measures manage loss