What drives the potato yield gap in China?

CONTEXT: China has the world's largest potato cultivation area, yet potato yield remains relatively low. A better understanding of current yield-limiting and reducing factors is essential to improve yield and input use efficiency. OBJECTIVE: This study aims to quantify yield gaps at the field level and uncover its main drivers for irrigated and rainfed potato farming systems across China. METHODS: We used 1836 field-year combinations from major potato-producing areas in China between 2019 and 2021. Potential yield (YP), water-limited yield (YW) and water- and nitrogen- limited yield (YWN) were simulated with World Food Studies model (WOFOST). The primary drivers of the yield gap in irrigated fields (Ygapᵢrri) and rainfed fields (Ygapᵣain) were explored using a WOFOST-based yield gap decomposition scheme and random forest model-based covariate importance analysis. RESULTS AND CONCLUSIONS: There remains substantial potential to increase potato yields in China. The highest Ygapᵢrri and Ygapᵣain were observed in the northern cultivation zone. The average Ygapᵢrri was 8. 2 t dry matter (DM) ha−1, with inadequate amounts and frequencies of irrigation identified as the main drivers, explaining 48. 8% of Ygapᵢrri. Optimising irrigation regimes and water-saving strategies are therefore necessary to close the yield gap. The average Ygapᵣain was 9. 9 t DM ha−1, and province-level socioeconomic covariates were the primary explanatory variables, particularly farmers' income and education level. This suggests that crop management can only be improved when farmers in rainfed areas have better access to financial resources, high-quality inputs and technical knowledge. Yield limitation due to insufficient rainfall was substantial (3. 5 t DM ha−1), indicating a notable water deficit across rainfed fields. Both approaches consistently identified nitrogen as the least influential factor for yield gap because of the general oversupply of N fertiliser, with half of the fields receiving more than 210 kg ha−1. SIGNIFICANCE: This study provides valuable recommendations for management practices and policy interventions aimed at narrowing the potato yield gap in China. The findings contribute to enhanced potato productivity and improved resource-use efficiency.