Abstract

The effects of soil fumigation (98% methyl bromide + 2% chloropicrin at 580 kg/ha) and N fertilizer (0, 12.5, 25, 50 or 100 kg N/ha) were examined in field trials on continuous wheat and wheat in rotation with lupins on the Geraldton sandplain. Fumigation increased grain yields at N fertilizer levels more or =25 kg/ha and was associated with reduced incidence and severity of common root rot (Bipolaris sorokiniana)[Cochliobolus sativus]. Grain yield was not significantly affected by rotation. Fumigation increased soil ammonium levels and decreased soil nitrate levels. Rotation of wheat and lupins increased mid-season growth at all levels of applied N but only increased grain yield where no N was applied.