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

Abstract

The effectiveness of manganese fertiliser for seed (grain) production of lupin (Lupinus angustifolius L.) was measured in 31 field experiments when manganese sulfate, applied at 0–15 kg manganese/ha was either: (i) placed (drilled) with the seed at about 5 cm; (ii) applied to the soil surface (topdressed) before sowing; or (iii) banded about 8 cm below the seed (13 cm below 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 increase 1100 kg seed/ha) followed by manganese drilled with the seed (average increase 845 kg/ha), while the topdressed manganese fertiliser was least effective (average increase 670 kg/ha). Additions of manganese fertiliser did not affect plant density (measured 1 month after sowing) or the yield of dried 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 is therefore recommended that manganese fertiliser is banded about 8 cm below the seed while sowing lupin rather than the present practices of either drilling the manganese fertiliser with the seed or topdressing it before sowing.