Less carbon emissions of wheat-maize intercropping under reduced tillage in arid areas

Intercropping is used to increase grain production in many areas of the world. However, this increasing crop yield costs large amounts of water used by intercropped plants. In addition, intercropping usually requires higher inputs that induce greenhouse gas emissions. Actually, it is unknown whether intercropping can be effective in water-limited arid areas. Here, we measured crop yield, water consumption, soil respiration, and carbon emissions of wheat-maize intercropping under different tillage and crop residue management options. A field experiment was conducted at Wuwei in northwest China in 2011 and 2012. Our results show that wheat-maize intercropping increased grain yield by 61 % in 2011 and 63 % in 2012 compared with the average yield of monoculture crops. The intercropping under reduced tillage with stubble mulching yielded 15.9 t ha(-1) in 2011 and 15.5 t ha(-1) in 2012, an increase of 7.8 % in 2011 and 8.1 % in 2012, compared to conventional tillage. Wheat-maize intercropping had carbon emission of 2,400 kg C ha(-1) during the growing season, about 7 % less than monoculture maize, of 2,580 kg C ha(-1). Reduced tillage decreased C emission over conventional tillage by 6.7 % for the intercropping, 5.9 % for monoculture maize, and 7.1 % for monoculture wheat. Compared to monoculture maize, wheat-maize intercropping used more water but emitted 3.4 kg C per hectare per millimeter of water used, which was 23 % lower than monoculture maize. Overall, our findings show that maize-wheat intercropping with reduced tillage coupled with stubble mulching can be used to increase grain production while effectively lower carbon emissions in arid areas.