An innovative integrated management strategy drives sustainable vegetable production in southwest China: Higher yield with reduced net GHG emissions

Intensive vegetable production in Southwest China is characterized by excessive fertilizer inputs, low nutrient use efficiency and high environmental costs. Thus, effective management strategies for sustainable vegetable production need to be explored. A two-year field experiment (2023-2024) was conducted to comprehensively evaluate the effects of different nutrient management strategies on vegetable yield and quality, net greenhouse gas (GHG) emissions, soil carbon (C) sequestration, and net ecosystem economic benefits (NEEB) from an openfield pepper (Capsicum annuum L.) production system in Southwest China. The six treatments included a control without fertilizer (CK), farmers' conventional practice (FP), three optimized nutrient management strategies (optimized NPK fertilizer, OPT; single-dose application of controlled release urea, CRU; and high-efficiency water-soluble fertilizer with nitrification inhibitor, WSF+NI), and an innovative integrated knowledge and product strategy (IKPS, which integrates optimized nutrient management, soil health and improved crop management). Compared with the FP treatment, the optimized nutrient management strategy decreased the fertilizer inputs by 43-62 %, increased the average pepper yield by 2.1-9.6 % and the nutrient use efficiency by 1.7-3.3 times. Compared with these optimized strategies, IKPS further significantly increased the vegetable yield, nutrient uptake and nutrient use efficiency by 12.4-20.8 %, 10.3-62.2 % and 31.9-83.9 %, respectively. Additionally, compared with those under FP, the three optimized nutrient management practices and IKPS significantly decreased the nitrite content in pepper fruits by 13.9-42.4 % and increased the vitamin C content by 60.5-77.6 %. These results indicated a comprehensive improvement in vegetable quality. Moreover, the net GHG emissions in the OPT, CRU, and WSF + NI treatments were reduced by 56.7 %, 72.1 % and 82.7 %, respectively, relative to those in the FP treatment, primarily because of the reduced fertilizer inputs. Compared with the three optimized nutrient management practices, the IKPS further improved soil C sequestration by 29.1-43.0 %, further reduced net GHG emissions by 47.2-78.9 %, and increased the NEEB by 33.2-47.2 %. The highest comprehensive evaluation index (CEI) was achieved with IKPS. These results confirmed its great potential as an innovative integrated management strategy to increase yields, improve economic and environmental benefits, and ultimately achieve sustainability in vegetable production. This study provides a template for sustainable vegetable production practices in subtropical regions, highlighting the importance of the IKPS for achieving carbon neutrality.