Impacts of water and land resources exploitation on agricultural carbon emissions: The water-land-energy-carbon nexus

•Theoretical framework of agricultural water-land-carbon-nexus was presented.•The Matching Degree of Water and Land Resources (MDWL) in China was analyzed.•Agricultural carbon emission and its intensity vary among China’s provinces.•The impact of MDWL on agricultural carbon emissions was discussed by LMDI model. Exploring the effect of water & land resource exploitation on agricultural carbon emissions helps explain agricultural “water-land-energy-carbon” (WLEC) nexus and improve the efficiency of agricultural water and land use. Based on the estimation of agricultural carbon emissions and provincial Matching Degree of Water and Land Resources (MDWL), this paper discussed the relationship between water & land resource exploitation and agricultural carbon emissions by Logarithmic Mean Divisia Index (LMDI) model, and put forward policy suggestions for the future low-carbon development of agriculture in China. The main conclusions are as follows: (1) The agricultural carbon emissions increased from 53.42 × 106tC in 2005–65.12 × 106tC in 2013, with an increasing rate of 21.89%. The carbon emission and its intensity have great spatial differences. (2) The MDWL of China fluctuated from 2005 to 2013, during which the MDWL in 2010 was the highest (1.56 × 106m3/km2). It has huge spatial difference across China. Generally, the MDWL of southern and eastern provinces was higher than that of northern and western provinces. (3) The order of contributing effect of each factor on agricultural carbon emissions is: economic output of water resources > the ratio of water and land resources > population factor > land use area per capita > agricultural carbon emission intensity. In those factors, agricultural carbon emission intensity is the main inhibitory factor, while the economic output of water resources is the main contributing factor. (4) The ratio of water and land resources has different effect on agricultural carbon emissions in different provinces. Generally, the inhibitory effect was much higher in the provinces with high MDWL than that of provinces with relatively lower MDWL. (5) To improve agricultural energy efficiency and promote carbon emission reduction, the agricultural technology should be improved, and land consolidation, large-scale operation, water-saving irrigation and the fallow rotation system of crops should be adopted.