Contribution of above- and below-ground interactions to intercropping

Abstract

Wheat/maize and wheat/soybean intercropping are the common cropping systems for high yield in the irrigated area of northwest part of China. A root barrier technique was employed to determine the relative contribution of above- and belowground interaction to yield and nutrient uptake in the intercropping systems. Land equivalent ratios (LER) of grain yield were 1.21–1.58 and 1.23–1.26 for wheat/maize intercropping and wheat/soybean intercropping, respectively. Grain yields of wheat located at border row increased by 74% and 53% over those at inner rows when intercropped with maize and soybean, respectively. Correspondingly, N uptake by the wheat at the border row increased by 109% and 53%. There were 98% and 54% increases of P uptake by wheat located at border row compared with those at inner rows. Potassium uptake showed a similar trend as for N and P uptake for the two intercropping systems. Out of the yield increase, 47 and 30% was attributed to above-ground interactions, and 27 and 23% attributed to below-ground interactions between two species in wheat/maize and wheat/soybean intercropping, respectively. The contribution of above-ground and below-ground interactions to the increase of N uptake by wheat were 50 and 59%, respectively, for wheat/maize intercropping and 23 and 20% respectively, for wheat/soybean intercropping. Similarly, contribution of above-ground and below-ground to the increase of P uptake were 56 and 42%, respectively, for wheat/maize intercropping, and 26 and 28%, respectively, for wheat/soybean intercropping.