What was achieved
- Increased understanding of how controlling resident grass species can promote subterranean (sub) clover growth during the spring and the value of applying fertilisers, particularly phosphorous, to improve clover yields.
About the study site
Early Valley, on the Port Hills above Tai Tapu, on Banks Peninsula, Canterbury, is a 25 ha large hill country lifestyle property owned by D. Schiel. The site is a North-West facing dryland hill pasture ~200 m a.s.l. with no fertiliser programme. Grazing is done by stock sourced from a neighbouring property as required. The existing pasture was dominated by browntop, sweet vernal and some clumps of cocksfoot with low populations of resident white and sub clovers. This site had recovered from being burnt in the Port Hills fires of 2017.
What was trialled
- The effect of phosphorous, sulphur and molybdenum fertiliser additions on oversown subterranean (sub) clover on dryland hill pasture sites were investigated.
- The herbicide treatment (330 ml Centurion Xtra/ha) was established to investigate the competition between grass and sub clover for nutrient uptake with the aim to suppress the grass growth to promote clover growth.
Key findings
- Herbicide application was the primary treatment influencing sub clover yield, which more than doubled with the application of herbicide.
- In the plots where herbicide was applied the sub clover then responded to the addition of phosphorus.
- The herbicide application suppressed the grass yield by 15%.
- Yield of white clover was increased by the addition of phosphorus fertiliser but was not affected by the herbicide treatment.
- The results highlight the value of controlling the resident grass species in mid-summer to promote sub clover seedling establishment in autumn and growth during the spring.
- Applying phosphorous is important improve clover yields.
Keen to know more?
Morton et al. 2021: A summary of research results on pasture responses to fertiliser and lime in the South Island hill and high country