Life cycle water and energy consumption and efficiency analysis of major crops in China

Water and energy are key elements in food production. However, only a few studies have investigated water and energy consumption simultaneously in a crop cultivation life cycle. In this study, we established a bottom-up framework to explore water and energy consumption in each period of the crop growth process, including sowing, germination, growth, maturation, and harvesting. We propose a novel homogenization index, the Water-Energy Efficiency for Food (WEEF) index, to compare crop production efficiency by reasonably eliminating regional location effects. Changes in water and energy consumption were evaluated for six major crops in China, including wheat, maize, rice, soybean, peanut, and cotton. The results showed that the water and energy consumption during the main growth period were largely synchronized in most regions, with peak periods occurring in July-August and May-June. Owing to the increased use of agricultural machinery and irrigation energy, the total energy consumption per unit yield of cotton, maize, and rice increased by 28%, 19%, and 16%, respectively, in 2018 compared with 2012, reaching 25.81, 2.53, and 2.49 MJ/kg, respectively. The WEEF index revealed that the efficiency of wheat and soybean production in China surpassed that of other crops. In general, the average crop production efficiency in the northern region was about 4% lower than that in the southern region. Implementing spatiotemporal refined water and energy management strategies is imperative to attain sustainable agricultural development.