Companion crop performance in relation to annual biomass production, resource supply, and subsoil drying

A field experiment located in NE Victoria compared the productivity of cereals sown into mature lucerne (companion crop) with cereals and lucerne grown as monocultures. Additional nitrogen (N) and water was applied to investigate if increased resource supply could alleviate competition and improve cereal performance in the presence of lucerne. Cereal plant populations, lucerne and cereal biomass, and cereal grain yields and protein were measured throughout the experiment. Soil water content was also monitored over time to determine whether companion cropping compromised the ability of lucerne to extract deep soil water. While companion cropping depressed both lucerne and cereal production, the combined annual biomass production was greater than cereal and lucerne when grown alone. Averaged over the three seasons, companion cropping resulted in a 31% increase ( P