NITROGEN USE AND MANAGEMENT IN ORCHARDS AND VEGETABLE FIELDS IN CHINA: CHALLENGES AND SOLUTIONS

Abstract

<List> <ListItem><ItemContent> ● Excessive application of N fertilizers in orchards and vegetable fields (OVFs) in China is particularly common. </ItemContent></ListItem> <ListItem><ItemContent> ● Long-term excessive application of N fertilizers has made OVFs hotspots for N surplus and loss in China. </ItemContent></ListItem> <ListItem><ItemContent> ● Nitrate accumulation in the soil profile is the main fate of N fertilizers in OVF systems. </ItemContent></ListItem> <ListItem><ItemContent> ● Reducing the N surplus is the most effective way to reduce N loss and increase NUE. </ItemContent></ListItem></List> China is the largest producer and consumer of fruits and vegetables in the world. Although the annual planting areas of orchards and vegetable fields (OVF) account for 20% of total croplands, they consume more than 30% of the mineral nitrogen fertilizers in China and have become hotspots of reactive N emissions. Excess N fertilization has not only reduced the N use efficiency (NUE) and quality of grown fruits and vegetables but has also led to soil acidification, biodiversity loss and climate change. Studies using ¹⁵N labeling analysis showed that the recovery rate of N fertilizer in OVFs was only 16.6%, and a high proportion of fertilizer N resided in soils (48.3%) or was lost to the environment (35.1%). Nitrate accumulation in the soil of OVFs is the main fate of N fertilizer in northern China, which threatens groundwater quality, while leaching and denitrification are the important N fates of N fertilizer in southern China. Therefore, taking different measures to reduce N loss and increase NUE based on the main pathways of N loss in the various regions is urgent, including rational N fertilization, substituting mineral N fertilizers with organic fertilizers, fertigation, and adding mineral N fertilizers with urease inhibitors and nitrification inhibitors.