Optimizing water-fertilizer integration with drip irrigation management to improve crop yield, water, and nitrogen use efficiency: A meta-analysis study

So far, many studies have examined the effects of drip irrigation and water-fertilizer integration on crop yield indices, nutrient use efficiency (NUE), and water use efficiency (WUE). However, they are carried out under different conditions. Due to the scattered research results and the lack of general conclusions from published results, it is necessary to use meta-analysis as a structured method to draw a conclusion. Therefore, a meta-analysis was conducted to quantitatively evaluate the effects of water–fertilizer integration with drip irrigation (WFI_DI) on nitrogen use efficiency (NUE), water use efficiency (WUE), and crop yield to explore the most suitable application strategy of WFI_DI, further discussion of its impact mechanism_. A total of 352 studies in the Chinese region were included, of which 84 studies met the entry criteria for the meta-analysis, and 779 pairs of data were finally obtained. The meta-analysis results showed that WFI_DI improved NUE (31.3 %), WUE (34.5 %) and crop yield (12.5 %) by changing soil physical and chemical properties (SOC increased by 36.4 %, TN increased by 9.3 %, and ET_C decreased by 11.5 %). In order to screen the key influencing factors and determine the applicable conditions, PCA and win-win analysis were carried out. The results showed that WFI_DI was suitable for food crops and fruit trees in medium-textured soils. It is recommended to use subsurface drip irrigation with a lower flow rate (≤1Lh⁻¹) and nitrogen fertilizer (10–25 % lower than the traditional nitrogen application rate of farmers). This study provides inspiration for efficient and economical agricultural water management.