Enhancing sustainable intensification via partial organic fertilizer substitution in a long-term vegetable rotation system

Partial organic substitution is being increasingly recognized as a promising strategy for regenerative agriculture. However, its integrated agronomic, ecological, and environmental performance in field-scale vegetable rotation systems, particularly under the humid subtropical conditions of South China, remains insufficiently investigated. Based on a 13-year field experiment, this study examined the effects of partial organic substitution on soil health, vegetable yield, and greenhouse gas emissions. Three fertilization regimes were compared: (1) an unfertilized control; (2) chemical fertilizer alone (CF); and (3) combined chemical and organic fertilization (CF+OF), in which 50% of chemical nitrogen was replaced with organic fertilizer. Compared with CF, CF + OF increased the soil health index by 14.3%, primarily owing to improvements in soil chemical and biological properties. Although vegetable yield was numerically higher under CF + OF than under CF (3.8%–7.2%), the differences was not statistically significant. CF + OF practice significantly reduced N 2 O emissions by 50.2%, primarily due to lower ammonium nitrogen availability and increased soil pH, and showed the lowest yield-scaled global warming potential (39.7 kg CO 2 eq Mg −1 ). A comprehensive sustainability index—integrating crop yield, N 2 O emissions, net CO 2 sequestration, yield-scaled global warming potential, and soil health—ranked CF + OF highest (0.80), followed by CF (0.55). Overall, these findings demonstrate that replacing 50% substitution of chemical nitrogen with organic fertilizer is a scientifically supported and practical strategy for promoting regenerative agriculture and sustainable intensification in long-term vegetable rotation systems under the humid subtropical climate of South China.