Lupin grain yields and fertiliser effectiveness are increased by banding manganese below the seed

The effectiveness of manganese fertiliser for seed (grain) production of lu pin (Lupinus angustifolius L.) was measured in 31 field experiments when ma nganese sulfate, applied at 0-15 kg manganese/ha was either: (i) placed (dr illed) with the seed at about 5 cm; (ii) applied to the soil surface (topdr essed) before sowing; or (iii) banded about 8 cm below the seed (13 cm belo w the soil surface) while sowing. Relative to the nil-manganese treatment, additions of manganese fertiliser increased yields by 190-1870 kg seed/ha. Increases were greatest for manganese banded below the seed (average increa se 1100 kg seed/ha) followed by manganese drilled with the seed (average in crease 845 kg/ha), while the topdressed manganese fertiliser was least effe ctive (average increase 670 kg/ha). Additions of manganese fertiliser did n ot affect plant density (measured 1 month after sowing) or the yield of dri ed shoots. A concentration of manganese in the main stem of about 20 mg/kg was a reliable predictor of manganese deficiency in lupin grain yield. It i s therefore recommended that manganese fertiliser is banded about 8 cm belo w the seed while sowing lupin rather than the present practices of either d rilling the manganese fertiliser with the seed or topdressing it before sow ing.