Spatio-temporal differentiation of carbon offset rate of conservation tillage and its evolution trend in China

An in-depth study of the net carbon effect of conservation tillage can provide an important basis for promoting green and low-carbon transformation of agriculture. This study considers the carbon offset rate of conservation tillage in 30 provinces (autonomous regions and municipalities, not including Hong Kong, Macao, Taiwan and Xizang of China, the same below) in China from 2000 to 2021. Using Dagum’s Gini coefficient and its decomposition method, it analyzes the regional differences in carbon offset rate and its causes among the main grain-producing area, the main grain-sales area, and balance of production and sales area. It also explores the dynamic evolution trend of these rates through spatial Markov chains and a dynamic convergence model. The study revealed that: 1) From 2000 to 2021, the carbon offset rate for conservation tillage showed an upward trend of carbon offset rate for conservation tillage in the main grain-producing area and a fluctuating downward trend in the main grain-sales area and the balance of production and sales area. The average annual growth rate in carbon offset rates for conservation tillage in main grain-producing area, main grain-sales area, and the balance of production and sales area were 0.402%, −0.729%, and −4.742%, respectively, showing significant spatial differences. However, the annual average contribution rate of the hypervariable density difference was as high as 51.01%, becoming the main source of regional differences in carbon offset rates for conservation tillage in China. 2) China’s conservation tillage carbon offset rate showed a strong “club convergence,” with a convergence of the development level and gradually narrowing gap, reflecting the existence of spatial dependence among provinces. 3) The α value of each region fluctuated, resulting in a national carbon offset rate for conservation tillage that did not exhibit an absolute convergence trend. The dynamic spatial absolute β and β conditional convergence values were insignificant and negative, which indicates that regional conservation tillage is unbalanced, and regional differences were not fully correlated with regional endowment conditions. Accordingly, strengthening the joint application of technology, giving full play to the spillover effect of technological innovation, and simultaneously formulating a sound institutional strategy, and accelerating cross-regional cooperation are recommended to promote the coordinated development of carbon offset rate for China’s conservation tillage. The results of the study can provide a reference for 30 provinces in China to establish a sound carbon offset mechanism for conservation tillage that meets regional characteristics, and contribute to the coordinated development of green and low-carbon agricultural economy and the realization of the “dual-carbon” goal.