Trends in the economic return on energy use and energy use efficiency in China's crop production

This study examines trends in energy input and output in China's crop production. Trends are also observed in energy use efficiency and economic return on energy use from 1991 to 2012. The results indicate that energy input increased from 3647.1 PJ to 7919.5 PJ and energy output increased from 7222.0 PJ to 10954.0 PJ between 1991 and 2012. Given the growth in the sowing area, energy input and output per unit of area sown also increased during this period. Energy use efficiency was estimated at 1.98 in 1991 and 1.38 in 2012, with an average annual decrease of 1.69%. The economic return on crop production in China increased from 1991 to 2012 whereas agricultural labor input decreased; consequently, the economic return on energy use, sowing area, and labor all increased stably. Given a larger growth rate and higher production of high-value and low-energy crops when compared with low-value and high-energy crops, an increase in the economic return on energy use occurred but so did a decline in energy use efficiency. This phenomenon indicates the need to increase investments in technological development and technological innovation, adopt new policies to optimize China's crop production structure, and establish sustainable production systems.