The effects of competition between Lotus pedunculatus cv. "Grasslands Maku", white clover (Trifolium repens cv. "Grasslands Huia") and browntop (Agrostis tenuis) at different levels of applied phosphate

Abstract

The effects of competition between browntop (Agrostis tenuis), white clover (Trifolium repens) and Lotus pedunculatus were examined at five levels of phosphate fertilizer applied to a moderately acidic, phosphorus deficient Cass high country yellow brown earth in a glasshouse pot trial.

This study demonstrated the ability of L. pedunculatus to outyield white clover at low levels of available soil phosphorus, but at high rates of fertilizer yields of the two species were similar. Although there was an indication that L. pedunculatus had a competitive advantage in terms of phosphorus uptake it did not significantly suppress the growth of white clover. The yield of the mixture of L. pedunculatus and white clover was generally intermediate to those of the two species growing alone. The balance of L. pedunculatus and white clover in the mixture was determined primarily by the level of phosphate fertilizer. Browntop reduced the yields of both legumes but had a greater effect on L. pedunculatus and markedly reduced the percentage of Lotus in the mixtures with white clover.

The results are discussed in relation to aluminium toxicity and competition for light, nutrients and soil oxygen.