Moisture and fertility interactions in a potted poplar-barley intercropping

Abstract

Through proper design and management of a tree-based intercropping system, ‘competitive’ interactions can be reduced and ‘complementary’ interactions promoted so that tree and crop components maximize sharing of resource pools. In this experiment, main and interaction effects of three levels of soil moisture (15 KPa, 15–50 KPa and 15–300 KPa) and three levels of soil N (35, 70 and 140 kg N ha−1), on growth, development and yield of intercropped poplar (Populus spp.) clone DN 177 and barley (Hordeum vulgare, var. OAC Kippen), were investigated in a potted greenhouse experiment. Barley growth and development and grain yield were significantly (p<0.05) affected by the levels of soil moisture and N tested but, growth and development of poplar was not. Moisture and N levels contributed their maximum effect to final grain yield when the other was presented in adequate quantities. However, the treatment combination of highest levels of moisture and N did not significantly affect the grain yield when compared to the combination of medium levels of moisture and N. It appears therefore that an increase in the level of moisture and N beyond an optimum level is not likely to significantly affect final grain yield or above ground biomass. There was no difference in the final grain yield or other parameters between the monocropped and intercropped barley, suggesting that poplar did not compete for moisture or N with barley. The total aboveground biomass produced per pot in the intercropped system was 14% higher than in the monocropped system. As there was no difference in the final grain yield, the tree intercropped treatment has an advantage over monocropped systems in terms of resource utilization.