Soil acidity and nodulation
Faba bean crops sown by farmers on acid soils in SA, Victoria and NSW were monitored in 2015 as part of a joint NSW DPI / GRDC project aimed at improving the performance of legumes in the Southern Region high rainfall zone. Results from winter / spring crop inspections highlight the importance of liming and improving soil pH in the main root zone, particularly in the top 15cm.
Faba beans and acid soils – making it work with lime and forward planning.
Growers have achieved high yields from faba beans – these are achievable if crops are effectively nodulated and root growth is not constrained by subsurface acidity. The 2015 observations have highlighted the impact of acid soils on growth and yield potential of faba beans; and this is relevant to any sensitive legume on acid soils.
- Faba bean and its specific Group F rhizobia are sensitive to pHCa below about 5.0
- Faba bean rooting depth is limited by acid layers in the soil profile
- Unincorporated, surface-applied lime increases pH of the soil surface, but has limited effect on subsurface pH in the short to medium term
- Lime incorporation to 10cm is necessary to rapidly increase subsurface pH
- Check for pH stratification before using Group B SU herbicides – elevated surface pH slows the breakdown of herbicide residue and may extend re-cropping intervals for legume species on acid soils to 22 months – check herbicide labels
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- Posted by Holbrook Landcare Admin
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