Quantification of Soil Water Competition and Compensation Using Soil Water Differences between Strips of Intercropping

Synergistic regulation on water competition and compensation is critical to effective use of water for sustainable intercropping systems in arid areas. Field experiment was carried out in 2009, 2010, and 2011 in Hexi Corridor, northwest China. Two late-sown crops [maize (Zea mays) and soybean (Glycine max)] intercropping with three early-sown crops [pea (Pisum sativum), rape (Brassia campestris), and wheat (Triticum aestivum)] were designed in comparison with the respective sole crops. Differences in soil water (soil water of late-sown crops minus that of early-sown crops in intercropping) were found to be mostly positive during the co-growth period which changed to negative during the fallow period of early-sown crops. Absolute values of the difference between wheat and maize strips both in co-growth and fallow period were the greatest among treatments, followed by maize–pea intercropping, while they were lowest in soybean–wheat intercropping in 2009 and 2010 and in maize–rape intercropping in 2011. In the co-growth period, the mean soil water competition for wheat strips in maize–wheat intercropping across 3 years was 71 mm, while it was 16 mm and 27 mm, respectively, for maize–rape and maize–pea intercropping. Sole wheat recharged the greatest amount of soil water from wheat harvest to maize harvest. In each year, intercropped wheat, rape, and pea recharged 24–76, 42–67, and 32–49 mm soil water, respectively. It was concluded that the methodology to calculate soil water competition and compensation was a very useful tool for evaluating the amount of soil water movement in intercropping systems. © 2014, NAAS (National Academy of Agricultural Sciences).