Effects of intercropping of maize and potato on sloping land on the water balance and surface runoff

It has been suggested that the increased yields of intercropping are strongly correlated to its effect on controlling water loss. However, studies of the effect of intercropping on controlling water loss on sloping land are few. In this study, with maize (Zea mays L.) and potato (Solanum tuberosum L.) as experimental crops, a comparison was made of surface runoff, soil evaporation, soil moisture content, crop transpiration and crop yield between the intercropping and the sole crop on sloping land during 2012-2013. Data showed that: (1) the accumulative runoff in maize and potato intercropping (IC) was not significantly different from that in sole potato (SP), but significantly decreased by 56.75-74.53% (P < 0.05) as compared with that in the sole maize (SM); (2) the daily mean soil evaporation in IC decreased by 20.83-28.44% (P < 0.05) as compared with that in SM, and decreased by 6.99-14.85% (P = 0.034 in 2012 and P = 0.064 in 2013) as compared with that in SP; (3) the soil moisture content in IC at each observation period was higher than that in SM and SP (P = 0.101 in late July and P < 0.05 in other periods); (4) the transpiration in IC was significantly higher than that in SM and SP (P < 0.05); and (5) the land equivalent ratio (LER) of IC was 1.19-1.34 (P < 0.05), indicating that the maize and potato intercropping induced a yield advantage. Overall, the results suggested that on sloping land, the maize and potato intercropping can reduce the water loss from the surface runoff and the soil evaporation, thus increasing the soil moisture content and contribute to the increase of the transpiration and crop yield. Data also indicated that the lower runoff in maize and potato intercropping compared with sole maize is associated not only with the higher leaf area index, but also with the potato tubers.