Risk of establishment failure or of poor establishment:
‘The most expensive pastures are those that fail to establish’. In general, perennial pastures are more difficult to establish than annual crops and pastures. Seedling growth is relatively slow compared with annual species, so good control of annual weeds is essential.
However, proven methods of establishment with a high success rate are now available for most perennial pasture types. Ensure all of the steps for successful establishment are undertaken to minimise the risk.
Last minute decisions to sow perennial pastures can be expensive if the necessary paddock preparation has not been carried out.
The perennial pasture establishes well, but subsequently fails to survive if there is a dry summer:
Well-adapted perennial pastures have proven highly drought tolerant. Ensure that the most suitable species are selected for the environment (soil, climate) and that all of the factors for successful establishment are undertaken.
Perennial plants need to develop a sufficiently large root system in the establishment year to survive the first summer. Excellent weed control during establishment is essential. Even when perennial plants survive weed competition during establishment, the result is smaller plants at the start of summer that will struggle to survive if there is a prolonged summer drought.
Do perennial pastures have more management requirements than annual pastures?
Most perennial pastures require some form of rotational grazing to persist and be productive in the medium- to long-term. Rotational grazing of annual pasture paddocks can significantly increase pasture production and utilisation.
Compared with the set stocking of annual pastures, there will be additional stock movement required with perennial pastures but this is more than off-set by the reduced need to supplementary feed stock in autumn.
Perennial pastures exacerbate problems with worm control in sheep:
This is not necessarily the case, as perennial pastures can change the dynamics of the worm population. There is reduced selection pressure for resistant worms as nonresistant worms can survive summer on perennial pastures.
As a result, the worm count is sometimes higher on perennial pastures, but the proportion of resistant worms may be lower
Perennial pastures become difficult weeds to control in crops:
The main perennial pasture species that are likely to be weeds in crops are lucerne, which is often grown in a phase rotation with crops, and kikuyu, which can be spread by stock in dung. A low density of lucerne plants in a cereal crop can adversely affect crop yields.
Methods for successfully removing lucerne before the cropping phase have been developed. Most perennial grasses are established as permanent pastures and the risk of spread around the farm is negligible. However, kikuyu can be spread by stock, so stock movement from kikuyu pastures into paddocks that will subsequently be cropped should be controlled.
Perennial pastures produce less feed than annual pastures:
Total dry matter production from well-managed annual and perennial pastures is usually comparable but perennial pastures have a more even seasonal distribution of dry matter production.
The term ‘perennial pastures’ is somewhat of a misnomer as most perennial pastures are a mix of perennial and annual species. At certain times of the year, the annual species may be the dominant component of the pasture.
Overall production can increase with a perennial-annual pasture, or at the least should be similar to a good annual pasture but with a better seasonal distribution.
Spring production from annual pastures is often higher than for many perennial pastures but perennial pastures are more productive in summer, autumn, and/or winter (depending on species and period of active growth) - when feed is often limiting.
Consequently, each unit of production is more valuable than the same production in spring when there is a surplus of feed resulting in poor pasture utilisation.
The ‘green bridge’ created by perennial pastures increases the incidence of pests and diseases in annual crops and pastures:
Perennial pastures do provide a ‘green bridge’ that can assist viruses and other pathogens to persist over summer. This risk can be reduced by only sowing virus-free seed and manipulating grazing to minimise potential problems.
The risk of ‘green bridge’ is reduced for diseases that are carried only on green foliage, as the seasonally dry conditions, which often extend from late spring to mid- to late autumn, ensure a substantial, continuous bridge of green foliage is rarely present away from isolated ‘wet’ areas.
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