Increasing crop nitrogen use efficiency while also simultaneously decreasing nitrogen accumulation in the soil would be key steps in controlling nitrogen pollution from agricultural systems. Long-term field experiments were started in 2003 to study the effects of intercropping on crop N use and soil mineral N accumulation in wheat (Triticum aestivum L. cv2014)/maize (Zea mays L. cv Shendan16), wheat/faba bean (Vicia faba L. cv Lincan No. 5) and maize/faba bean intercropping and monocropping systems. Monocropping was compared with two types of strip intercropping: continuous intercropping (two cropsintercropped continuously on the same strips of land every year) and rotational intercropping (two crops grown adjacently and rotated to the other crop's strip every year). Maize/faba bean intercropping had greater crop N uptake than did wheat/faba bean or wheat/maize. Wheat/maize accumulated more mineral N in the top 140 cm of the soil profile during the co-growth stage from maize emergence to maturity of wheat or faba bean. Continuously intercropped maize substantially decreased soil mineral N accumulation under wheat and faba bean rows (60'100 cm soil depth) at maize harvest. Soil mineral N accumulationunder wheat rows increased with rotational intercropping with faba bean. Rotational intercrop- ping may potentially alleviate the adverse effects of wheat on N use by other crops and increase the nitrogen harvest index of wheat, maize and faba bean. Intercropping using species with different maturity dates may be more effective in increasing crop N use efficiency and decreasing soil mineral N accumulation.
Li, C. J., Li, Y. Y., Yu, C. B., Sun, J. H., Christie, P., An, M., Zhang, F. S., & Li, L. (2011). Crop nitrogen use and soil mineral nitrogen accumulation under different crop combinations and patterns of strip intercropping in northwest China. Plant and Soil, 342(1-2), 221-231. https://doi.org/10.1007/s11104-010-0686-6