Aimed at identifying factors limiting the production and nitrogen fixation of pulse crops grown on acidic soils in the high rainfall zone (HRZ) grain production regions of south eastern Australia with a long-term average annual rainfall above 500 mm.

• Most legumes favour pHCa > 5.0 to a depth of at least 20 cm; acidic layers below 5 cm adversely affect root growth, nodulation, plant vigour and N2 fixation potential of acid-sensitive pulses.
• Ineffective incorporation of lime under minimum tillage systems confines the lime effect to the shallow surface layers (0-5 cm).
• An ‘acid throttle’ located between 5 to 20 cm in the soil profile is not detected using soil samples collected at standard depths of 0-10 cm and 10-20 cm, finer sampling at 5 cm intervals is recommended to detect acidic layers.
• Apply and incorporate adequate rates of fine grade, high quality lime at least 12 months before sowing acid-sensitive species to allow time for the lime to react and increase pH to the depth of incorporation.