Characterization of the spatio-temporal divergence of eco-efficiency of cultivated land use using grey water footprint in the Yangtze River Economic Belt of China

The Yangtze River Economic Belt confronts the paradoxical challenge of agricultural growth and substantial water environmental contamination. Enhancing the eco-efficiency of cultivated land use while considering water environment limitations has emerged as a pivotal approach to harmonizing economic and ecological benefits in cultivated land utilization, thereby holding significant implications for exploring ecologically sustainable modes of cultivated land utilization and achieving green agricultural development. In light of this, a cultivated land use eco-efficiency evaluation index system is developed in this study, using the connotation definition of cultivated land use eco-efficiency from the standpoint of the grey water footprint. This study utilized the SBM-Undesirable model to assess the eco-efficiency of cultivated land use in 130 cities within the Yangtze River Economic Belt for the period from 2000 to 2020. Additionally, the spatial and temporal trends in eco-efficiency of cultivated land use, as well as their evolution from 2000 to 2020, were analyzed utilizing the spatial autocorrelation and Markov chain models. The findings indicate that the average grey water footprint value of the Yangtze River Economic Belt exhibited an initial increase followed by a subsequent decrease from 2000 to 2020. The decline in the grey water footprint value after 2015 was more pronounced, potentially attributable to the implementation of ecological management projects such as non-point source pollution control and reduction in fertilizer and pesticide usage in response to national policies across all regions. Simultaneously, the spatial distribution pattern of the grey water footprint demonstrated a " high in the east and west, low in the middle" trend, with higher values primarily concentrated in major grain-producing provinces. The intensive utilization of cultivated land and excessive resource consumption further exacerbated water environment pollution and ecological degradation within these regions. Throughout the period from 2000 to 2020, there has been a continuous decline in the eco-efficiency of cultivated land use within the Yangtze River Economic Belt, with an average efficiency level ranging between 0.5 to 0.8 indicating significant room for improvement. Notably, distinct regional disparities exist regarding the eco-efficiency of cultivated land use among upper, middle, and lower regions due to variations in environmental quality gradients, socio-economic development levels, and unequal allocation of production factors. The results of spatial autocorrelation and Markov chain model analysis reveal a significant positive spatial correlation in the eco-efficiency of cultivated land use within the Yangtze River Economic Belt, exhibiting evident geographical heterogeneity in its distribution. However, regions with high eco-efficiency of cultivated land use may exhibit dispersed spatial patterns or unstable input-output structures, potentially hindering collaborative and efficient utilization of cultivated land for green agricultural development. Considering the evolutionary trend observed during the study period, improvements in eco-efficiency of cultivated land use are challenging to achieve due to path dependence. Nevertheless, their stability is influenced by spatial factors. The influence of neighborhood background often leads to the "club convergence" phenomena in space, where both "high-high cluster" and "low-low cluster" distributions are commonly observed. In light of these findings, it is imperative to implement differentiated precision agriculture models and enhance measures for controlling agricultural non-point source pollution. Simultaneously, attention should be paid to fostering dynamic inter-regional development through increased financial support for agriculture. Directional agricultural policies can provide support for areas with inefficient eco-efficiency of cultivated land use, prompting input-output structure transformation and upgrading. Ultimately, this will lead to increased eco-efficiency of cultivated land use.