Interspecific facilitation of nutrient uptake by intercropped maize and faba bean

Interspecific complementary interactions in N, P and K uptake between intercropped maize (Zea mays L. cv. Zhongdan No. 2) and faba bean (Vicia faba L. cv. Linxia Dacaidou) were investigated in a field experiment. A root barrier study was also set up in which belowground partitions were used to determine the contribution of interspecific root interactions to crop nutrient uptake. Nitrogen uptake by intercropped faba bean was higher than (no P fertilizer) or similar to (33 kg P ha(-1) of P fertilizer) that by sole faba bean during the early growth stages (first to third sampling) of faba bean, and was similar to (no P fertilizer) or higher than (33 kg P ha(-1) of P fertilizer) that by sole faba bean at maturity. Nitrogen uptake by intercropped maize did not differ from that by sole maize at maturity, except when P fertilizer was applied. Intermingling of maize and faba bean roots increased N uptake by both crop species by about 20% compared with complete or partial separation of the root systems. Intercropping also led to some improvement in P nutrition of both crop species. Maize shoot P concentrations were similar to those of sole maize during early growth stages and became progressively higher until they were significantly higher than those of sole maize at maturity. Intercropping increased shoot P concentration in faba bean at the flowering stage and in maize at maturity, and increased P uptake by both plant species at maturity. Phosphorus uptake by faba bean with root intermingling (no root partition) was 28 and 11% higher than with complete (plastic sheet) and partial (400 mesh nylon net) root barriers, respectively. Maize showed similar trends, with corresponding P uptake values of 29 and 17%. Unlike N and P, K nutrition was not affected by the presence of root barriers.