Abstract
<title>Abstract</title> <p>Green agricultural technologies are central to reconciling food security with environmental protection, yet their joint ecological and economic returns remain poorly understood. (1) Background: This study examines the ecological benefits, economic benefits, and the mechanism linking the two that arise from organic fertilizer application, using banana cultivation as a case. (2) Methods: Drawing on survey data from 650 banana farmers in Hainan, Guangdong, Guangxi, and Yunnan—China’s four major banana-producing regions—we estimate a system of benefit equations (total carbon emissions per mu, soil-fertility improvement, net income per mu, and sales price premium) using Seemingly Unrelated Regression (SUR), which accounts for the contemporaneous correlation among multiple co-determined outputs. (3) Results: Organic fertilizer raises per-area carbon emissions in the short run because of decomposition, but markedly improves soil fertility, indicating a transition from a short-term “carbon source” to a long-term “carbon sink”. Economically, the gains stem mainly from a quality-driven price premium rather than from higher yield, and education and household labour are decisive. Benefits diverge by farm scale: small, intensively managed farms have an ecological edge, whereas large farms face a short-term “high-carbon” lock-in. Government subsidies show no significant income effect and suffer from targeting errors. (4) Conclusions: A differentiated subsidy regime, reformed extension, an “organic + carbon-footprint” dual-certification scheme, and carbon-sink trading are recommended to raise incomes while protecting the environment.</p>