Organic waste recycling for green and sustainable nitrogen management of fruit production systems in China

CONTEXT: The increasing adoption of green agricultural development and recycling of agricultural resources policies in China in the recent past has led to the partial replacement of synthetic fertilizers with organic alternatives for fruit production. However, the nature, extent, and impact of this sustainable nitrogen (N) nutrition transition, i.e., combined synthetic and organic N fertilizer (combined N) use on the yield of fruit crops, fruit quality and soil quality remain unclear at the national level. OBJECTIVE: The purpose of this study was to determine the effect of the combined application of organic and synthetic fertilizers on fruit-production systems in China and to gain more insight into the sustainable N management of fruit crops. METHODS: A meta-analysis of peer-reviewed papers on this topic published from 2000 to 2022 was conducted. We conducted a meta-analysis of 84 studies with 399 comparisons in Chinese fields to examine the effects of combined N application on fruit yield, fruit quality and soil quality, and to identify the key factors in conjunction with random forest plots. RESULTS AND CONCLUSION: The overall fruit yield, single-fruit weight, fruit soluble solids content, vitamin C content, and fruit solidity-acid ratio increased by 9.8%, 6.4%, 4.9%, 12.8%, and 14.8%, respectively, and the fruit titratable acid content decreased by 8.6% with combined N application. Additionally, compared with those that received synthetic N fertilizer only, the soil organic matter (SOM) content in the orchards fertilized with combined N increased by 20.0% and the soil pH increased by 1.1%. More specifically, when the organic N substitution rate (SR) was <= 70%, the fruit yield increased by similar to 12%. The increases in soil pH, available N and available phosphorus (P) following combined N application were more pronounced in southern China than in northern China. Random forest analysis further revealed that the N application rate and SOM content were the two variables most related to fruit yield, fruit quality and soil quality, and geographic location was the most important variable explaining soil pH. SIGNIFICANCE: These findings expand our understanding of sustainable N management and agricultural resource use and policy recommendations for sustainable orchard N management and high-quality fruit production in China and other countries with similar fruit production conditions.