 Glenfoyle Station, in the upper Clutha, is typical of many South Island high country farms with large areas of over-sown tussock country. Glenfoyle has had a good history of superphosphate application, but despite this, in recent years feed production and quality appears to be deteriorating. This problem is common to many high country properties.
A Merino Benchmark Group study by P Espie & R Dolby in 2004 identified high aluminium levels on Glenfoyle’s Blackstone Hill soils as being a key factor limiting pasture production. High aluminium levels occur when soil pH is low with the effect of restricting root development, particularly in clovers. This limits the plant’s ability to take up nutrients and hence the potential benefit of fertiliser applications. Poor root development reduces the plant’s ability to take up water, increasing stress during dry periods. Aluminium toxicity also inhibits nodulation of legumes. Lifting the low pH levels will address the aluminium toxicity. Steep terrain (requiring aerial application) and proximity mean that transport and application costs are a significant issue for this type of hill country operation. Optimise is being trialled at relatively low application rates as a means of minimising the cost of addressing these key soil fertility issues. Trial Environment & Treatments The trial area is on steep terrain at an elevation of 790m with an average rainfall of 675mm annually. Vegetation includes native grasses that has been previously over-sown with improved species. The trial consists of replicated control plots and treatments as follows:
24-Month Results Soil tests have been taken every three months following application. These results are charted below. A sustained response has been measured in both increased soil pH and reduced exchangeable aluminium levels. Regular monitoring will continue with results available online at www.optimise.net.nz |
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