REQUIREMENT OF FIELD PEA FOR INOCULATION WITH RHIZOBIUM AND LIME PELLETING IN SOILS OF WESTERN-AUSTRALIA

The requirement of field pea (Pisum sativum) for seed inoculation with Rhizobium and for lime pelleting of inoculated seed was investigated in field experiments in the south-west of Western Australia, especially at locations where inoculated field pea had been grown 2 years previously. At most sites with previous pea cropping, the nodulation, total dry matter and nitrogen, and grain yield of pea were not improved by seed inoculation or lime pelleting. At these sites soil populations of R. leguminosarum bv. viciae at sowing were >10(3)/g soil. Responses to inoculation were measured at sites where the soil was very acidic [pH(CaCl2) <4.5], or mildly acidic (to pH 4.9) and of light texture (>90% sand + gravel), or where pea had not grown previously. There were fewer rhizobia at sowing at these locations. Lime pelleting was not generally required to maximise field pea growth or yield, but yield was affected by the inoculant Rhizobium strain.