Dr Liz Farquharson suggests growers follow the GRDC Back-Pocket Guide for the best response to legume inoculation.
New GRDC-funded research by the South Australian Research
and Development Institute (SARDI) has confirmed that field peas are unlikely to
respond to inoculation, unless they are grown on acidic soils or where there is
no recent history of the crop.
SARDI soil biologist Dr Liz Farquharson says the study found
Rhizobium inoculation did not cause a grain yield response in field pea grown
on soils where there was a history of growing the crop and neutral to alkaline
“This was despite evidence of positive effects of
inoculation on nodule mass and grain nitrogen content. On these soils, it would
appear that the rhizobia in the soil are not limiting the yield of field pea.
Nodulation and N2
-fixation did not always meet our expectations,
suggesting factors other than the rhizobia might be limiting to the symbiosis.”
Field pea, faba bean and lentils are all inoculated by the
same rhizobia, so a history of any of the three crops is likely to indicate
there is adequate rhizobia in the soil.
“We are reluctant to discount the possibility of a response
in faba bean from inoculation at this stage, as it produces more biomass,
however we anticipate the response in lentils would be the same as field pea,” Dr
The GRDC Back Pocket Guide advises that the likelihood of
crop response to inoculation is:
High if there is no history of pea, vetch, bean or lentil crops, or soils with pH (CaCl2) below 6.0 and high summer temperatures (over 35oC for 40 days).
Moderate if there was a previously inoculated pea, vetch, bean or lentil crop more than four years ago, or a recent crop which nodulated poorly and performed below expectation.
Low in loam or clay soils with neutral
to alkaline pH, and a recent well-nodulated host crop.
SARDI is a division of Primary Industries and Regions SA.
Liz Farquharson, 08 8303 9452, firstname.lastname@example.org
GRDC Project Code