Interactions between intercropped Avena sativa and Agropyron cristatum for nitrogen uptake

Aims The effect of cropping regime on nitrogen (N) uptake in two coexisting plant grass species (Avena sativa and Agropyron cristatum) was investigated. Methods The two grass species were cultivated by monocropping or intercropping. N-15-labeling was used to examine N uptake of NH4+ versus NO3- at 0-5 cm and 5-15 cm soil depths. Results The aboveground and total biomass of intercropped A. sativa was 1.3 times greater than monocropped A. sativa. The biomass of A. cristatum did not change between cropping systems. In the 0-5 cm soil layer, uptake of NO3- by A. sativa was 0.5 times less in the intercropped system than in the monocropped system, whereas uptake of NO3- by A. cristatum was 2.0 times more in the intercropped system. In the 5-15 cm depth, intercropping did not change N uptake by A. sativa but decreased NO3- uptake to 0.6 times by A. cristatum. Conclusions Complementarity in N uptake between A. sativa and A. cristatum in the upper 0-5 cm soil layer is conducive to biomass accumulation. Intercropped A. sativa and A. cristatum does not compete strongly for soil resources and can alter their N uptake patterns to optimize biomass production.