Inter- and intra-species intercropping of barley cultivars and legume species, as affected by soil phosphorus availability

Aims: Intercropping can improve plant yields and
soil phosphorus (P) use efficiency. This study
compares inter- and intra-species intercropping,
and determines whether P uptake and shoot biomass
accumulation in intercrops are affected by
soil P availability.
Methods: Four barley cultivars (Hordeum vulgare L.)
and three legume species (Trifolium subterreneum,
Ornithopus sativus and Medicago truncatula) were selected
on the basis of their contrasting root exudation
and morphological responses to P deficiency. Monocultures
and barley-barley and barley-legume intercrops
were grown for 6 weeks in a pot trial at very limiting,
slightly limiting and excess available soil P. Aboveground
biomass and shoot P were measured.
Results: Barley-legume intercrops had 10–70%
greater P accumulation and 0–40% greater biomass
than monocultures, with the greatest gains occurring
at or below the sub-critical P requirement for
barley. No benefit of barley-barley intercropping
was observed. The plant combination had no significant
effect on biomass and P uptake observed
in intercropped treatments.
Conclusions: Barley-legume intercropping shows
promise for sustainable production systems, especially
at low soil P. Gains in biomass and P uptake
come from inter- rather than intra-species
intercropping, indicating that plant diversity resulted
in decreased competition between plants for P.