Energy Use and Greenhouse Gas Emissions from Chemical Fertilizer Application in Crop Production in the Middle Reach of Yangtze River After Implementing Zero-Growth Actions

ABSTRACT: Minimizing energy inputs and greenhouse gas (GHG) emissions is essential for achieving sustainable crop production. This study analyzed changes in energy use and GHG emissions associated with chemical fertilizer application in crop production in the middle reach of the Yangtze River from 2014 (one year before the implementation of zero-growth actions) to 2022. Results revealed significant reductions in both total energy inputs and energy inputs per unit area from chemical fertilizers, with annual declines of 10.72 PJ and 0.48 GJ·ha⁻¹, respectively. The energy use efficiency of chemical fertilizer application increased significantly at an annual rate of 0.40. Concurrently, total GHG emissions, emissions per unit area, and emissions per unit of energy input associated with chemical fertilizer application decreased significantly, with respective annual reductions of 0.31 × 10⁷ kg, 14.08 kg·ha⁻¹, and 0.26 kg·GJ⁻¹. These reductions were primarily due to decreases in inputs of straight nitrogen (N), phosphorus (P), and potassium (K) fertilizers, rather than changes in compound fertilizers, as the input of compound fertilizers saw a significant increase. This study suggests that zero-growth actions, with the substitution of compound fertilizers for straight N, P, and K fertilizers as a key approach, are associated with lower energy inputs and GHG emissions from chemical fertilizer application in the middle reach of the Yangtze River. However, given the descriptive nature of this analysis, these findings should be interpreted as correlational, and further quasi-experimental studies are warranted to confirm causality.