Effect of root interaction on growth and N uptake in a hedgerow and soybean intercropping system

With root partition method and 15N tracing technique, a pot experiment was conducted to study the effect of root interaction on plant growth and nitrogen uptake in a hedgerow and soybean intercropping system. The hedgerow species evaluated were Amorpha fruticosa and Vetiveria zizanioides. The results showed that the nitrogen uptake of soybean with no root and mesh separation in the Vetiver-soybean system was 20.1% and 0.6% higher than that with sheet separation, and nitrogen acquisition of Vetiver was increased by 7.4% and 24.2%. In the A. fruticosa-soybean system, however, the nitrogen uptake of soybean with no root and mesh separation was 28.3% and 15.9% lower than that with sheet separation, and nitrogen acquisitions of A. fruticosa was decreased by 14.3% and 24.3%. 15N% abundance of soybean with mesh separation in the Vetiver-soybean system was lower than that with no root separation and higher 15N% abundance of Vetiver was observed in no root separation. In the A. fruticosa-soybean system, lower 15N% abundance of soybean and A. fruticosa was observed in no root separation. These results indicated that the growth of soybean was unexpectedly suppressed in two intercropping systems. The growth of A. fruticosa was also suppressed due to root interaction, yet the growth of Vetiver was enhanced significantly. The root distribution pattern may play an important role in nitrogen uptake.