Where to grow Miscanthus
Miscanthus yields have been modelled in New Zealand since 2010. Key determinants of yield are sunshine, temperature, and water availability. Annual variability in these factors result in annual yield variations. For any site micro-climatic conditions such as aspect will also affect annual yield. Harvestable yields in New Zealand vary on average between approximately 10 tonne/ha to around 30 tonne/ha.
Annual rainfall and soil water retention will strongly influence the yield of Miscanthus at any site. Miscanthus possesses good water use efficiency when based on the amount of water required per unit of biomass and Miscanthus roots can penetrate and extract water to a depth of around 2m. However, to achieve high yields, Miscanthus may need more water than the crops that it may replace.
In addition, a dense canopy means that 20-30 % of rainfall is intercepted by, and evaporates off, the leaves and never reaches and infiltrates into the soil. Limited soil water availability during a growing season will prevent the crop from reaching full potential yield in that year.
In times of severe drought, the foliage of Miscanthus will first show leaf rolling and then die back from the leaf tip. This will reduce yield in the year of drought, but the crop will survive and re-grow the following year.
Miscanthus has been reported growing and producing high or reasonable yields on a range of soils, from sands to high organic matter soils. It is also tolerant of a wide range of pH, but the optimum is between pH 5.5 and 7.5. Miscanthus is harvested in the early spring.
The fallen leaf material and the rhizome mat below the soil surface provide very stable ground conditions for harvesting.
The potential climatic zones for Miscanthus are widespread. Miscanthus does not grow at temperatures below a threshold of 6oC. This is considerably lower than for maize and therefore the potential growing season is longer. Late spring frosts which destroy early spring foliage and effectively reduce the duration of the growing season are the major constraint to long season growth.
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