Abstract: In order to explore the present situation of agricultural water resources use efficiency in China under the background of “Dual Carbon”, the SBM-Undesirable model with agricultural carbon emissions as undesirable output was established to measure and evaluate agricultural water resources use efficiency in three functional grain zones in China from 2011 to 2019. Then the Dagum Gini coefficient decomposition method was used to analyze the regional differences and sources of water resources use efficiency within and among the three functional grain regions. The results showed that the overall agricultural water resources use efficiency in China was at a high level, but there were dual problems of decreasing efficiency and increasing imbalance. There were great differences and significant synergies in agricultural water resources use efficiency among different regions. The water resources use efficiency was in the most stable equilibrium state within the grain main sales area. The contribution of supervariable density was the main source of the difference between groups of agricultural water resources efficiency in functional grain areas. Therefore, differentiated and targeted policies should be implemented according to the actual situation of each region, so as to comprehensively improve the efficiency of agricultural water use in China and promote the development of low-carbon and water-saving agriculture.

Key words: agricultural water resources use efficiency, SBM-Undesirable model, Dagum Gini coefficient, functional grain zone