The effect of form of applied phosphate and PH on the growth and nutrition of Russell lupin (Lupinus polyphyllus x Lupinus arboreus) and 'grasslands maku' lotus (Lotus pedunculatus) on a high country yellow brown earth

Abstract

In a glasshouse study the response of Russell lupin (Lupnius polyphyllus x Lupinus arboreus) and 'Grasslands Maku' lotus (Lotus pedunculatus) to different forms of phosphate and increased in pH on a high country yellow brown earth was investigated. Rock phosphate and superphosphate were applied at 50 kg/ha. Soluble phosphate was applied as KH₂P0₄ at 3 mMol l⁻¹. The pH of the soil (initially pH 5.4) was increased one pH unit to 6.4 with Ca(OH)₂. Plants were grown over 101 days with sequential harvests at 59,80 and 101 days after sowing.

Over the 101 days lupins consistently produced more dry matter than lotus (P< 0.001). Lotus had a higher shoot to root ratio than lupin (2.16 and 1.17 respectively). With both dry matter and phosphate uptake lupins performed better than lotus with no applied phosphate and with rock phosphate.

Phosphorus concentration of the herbage of both legumes was similar at final harvest (lupins 0.18% and lotus 0.19%). With regard to aluminium both legumes had similar AI shoot concentrations however the root concentration of Al in lotus was considerably higher than in lupins (0.68% and 0.30% respectively).