Optimizing nitrogen input in orchard systems to balance agronomic productivity and environmental protection
摘要
It remains uncertain whether one can achieve a balance between productivity and environmental sustainability in orchard systems by reducing nitrogen (N) fertilizer inputs and minimizing environmental N losses. This study addresses this knowledge gap by synthesizing data from 108 peer-reviewed articles before April 2023 on the impacts of N inputs on fruit yield, nitrate (NO3–) leaching, nitrous oxide (N2O) emissions, and ammonia (NH3) volatilization. We found that an optimal N input of 165 kg N ha–1 yr–1, a fruit yield of 79 kg N ha–1 yr–1, and a N use efficiency (NUE) of 34% balanced both fruit yields and environmental N losses; further increases in N input beyond the optimum led to a diminishing increase in fruit yield and a diminishing NUE. Reducing N inputs by up to 30% to more than 60% of the commonly used N rate under standard agricultural practices resulted in a slight drop in fruit yield (6% to 13%), but it also resulted in significant reductions in NO3– leaching (27% to 50%), N2O emissions (22% to 56%), and NH3 volatilization (57% to 67%), although the direction and magnitude of these effects were site-specific. This practice effectively reduced environmental N loss, with minimal yield penalties observed in orchards of higher N inputs. N fertilization methods notably affected the reduction of environmental N losses in orchard systems. We identified tree age, soil pH, and irrigation regime as key regulators of N fertilizer reduction on environmental N loss and fruit productivity. The current study provides insights into the impact of N input reductions on environmental N loss and fruit yield sustainability in the framework of global orchard intensification.