Agricultural water use efficiency and spatial spillover effect considering undesired output in China

Abstract Solving the problem of agricultural water use efficiency is an effective means to understand the agricultural ecological civilization and food security. In order to balance the relationship between agricultural water efficiency and regional economic size, this study examines the agricultural water use efficiency in China based on the Super-SBM model of unexpected output. At the same time, the Spatial Durbin Model (SDM) was introduced to analyze the spatial spillover effect and try to find ways to improve agricultural water use efficiency from the perspective of influencing factors. The present study used the panel data of 30 provinces in China from 1998 to 2018 to obtain empirical results. The results show that (1) China's agricultural water resources’ utilization efficiency in 21 years has not remained high: the results showed that it was 0.496 in 1998, 0.572 in 2008, and 0.657 in 2018, but it is slowly rising which explains that the low efficiency is mainly caused by the low pure technical efficiency. (2) The overall agricultural water use efficiency in China is in a situation of spatial agglomeration but there has been a trend of shifting positive correlations to negative correlations among neighboring provinces. It found that in 1998, the sum of the number of `High-high agglomeration type' and `low-low agglomeration type' provinces was 20, and the sum of `low-high agglomeration type' and `high-low agglomeration type' provinces was 10. In 2018, the total number of `high-high agglomeration type' and `low-low agglomeration type' provinces decreased to 12, while the total number of `low-high agglomeration type' and `high-low agglomeration type' provinces increased to 18, which specifically manifested as a negative spillover effect. (3) During the research period, the province's agricultural fixed asset investment, fiscal expenditure on agriculture, forestry, and water affairs, the number of years of education of rural residents and the increase in crop sown area have positive impacts on the efficiency of agricultural water use in the province. Meanwhile the transfer of labor and increase in the disposable income of rural residents reduced the efficiency of agricultural water use in the province. Fixed agricultural investment, labor transfers, and financial expenditures for agriculture, forestry, and water affairs in neighboring provinces have negative impacts on the province's agricultural water use efficiency. The impact is specifically manifested as a negative spatial spillover effect. As a result, China's agriculture will move towards healthy and green development. Therefore, the efficiency of agricultural water use needs to be comprehensively improved.