Grain yield and soil respiratory response to intercropping systems on arid land

Intercropping systems have been shown to boost crop productivity and provide potential for biodiversity in the development of sustainable agriculture, but little is known about the effect of intercropping on soil respiratory responses and CO2 regulations. This study determined grain yields, soil respiration (Rs) rates and their relationships to soil temperatures (Ts), dry matter (DM) accumulation, and carbon emission (CE) for maize (Zea mays L.)–pea (Pisum sativum L.) and maize–wheat (Triticum aestivum L.) intercropping, in comparison with sole pea, sole wheat, and sole maize, in an arid environment. Field experiments were conducted at Wuwei Experimental Station in 2009–2011. Maize produced the greatest grain yield at 11,724 kg ha−1, followed by wheat averaging at 6467 kg ha−1, and pea the lowest at 2830 kg ha−1. Sole maize had the grain yield decreased from 12,677 kg ha−1 in 2009 to 10,624 kg ha−1 in 2011, or by 19%, whereas the maize in the maize–wheat intercropping had its grain yield increased from 7404 kg ha−1 in 2009 to 8123 kg ha−1 in 2011, or by 10%. Maize-based intercropping had significant yield advantages over sole wheat and sole pea, with maize–wheat and maize–pea having land equivalent ratio of 1.2–1.5. Diurnal Rs had a single peak occurring from 12:00 to 14:00 h during a day, whereas seasonal Rs changed from seedling to maturity with Rs reaching the peak in June or July. A quadratic function for DM combined with an exponential function for Ts was used to fit the measured results, showing the combination of DM and Ts accounted for 24–45% of the Rs variation. Sole maize was the highest carbon emitter, averaging 4233 kg C ha−1 per year, and sole pea the least emitter, averaging 1448 kg C ha−1 per year. Across the three years, the maize–wheat system had an average carbon emission (CE) of 2888 kg C ha−1, or 47% less compared to sole maize; the maize–pea system had CE of 2635 kg C ha−1, or 61% less compared to sole maize. Adoption of intercropping systems especially the inclusion of a legume like pea is an effective approach to increase crop productivity, reduce soil respiration, and lower carbon emission in arid lands.

► Intercropping boosted grain yield with land equivalent ratio >1.2.
► Soil respiration peaked when maize was approaching bell-mouth stages.
► Soil respiration was closely related to dry matter and soil temperature.
► Sole maize was the highest carbon emitter, and sole pea the lowest.
► Maize–pea intercropping is the most favorable system in arid land.