Rotational grazing of Phalaris will improve the productivity and persistence of the pasture by allowing the plants to fully utilise their natural replenishment and dormancy mechanisms.
Phalaris is a deep rooted winter active perennial grass that has greater rooting depth than other perennial grasses such as Cocksfoot or Perennial Ryegrass, and a true summer dormancy mechanism. These characteristics make Phalaris much more persistent than other perennial grass species.
Growth rate and persistence of Phalaris is reliant on stored water soluble carbohydrates (WSC) in the roots and stems of the plant. WSC are required to produce the first leaf after grazing and are replenished by photosynthesis as new leaves grow. Rotational grazing of Phalaris will prevent continual grazing down of the growing point and allow plants to build and maintain WSC levels which results in longer persistence.
The maximum level of stored WSC is reached once there are four fully expanded leaves on each tiller. This is the optimum time to graze Phalaris.
The rest period required for Phalaris to reach the four leaf stage depends on soil moisture and temperature. Research from Victoria found that rest periods of 70 days in summer, 30-50 days in autumn, 40-60 days in winter and 20 days in spring were required for the Phalaris to reach the four leaf stage prior to grazing.
For Phalaris to persist in the long term, it is important that tillers develop dormant buds during spring each year.
Phalaris changes from vegetative to reproductive growth after a period of 5-10oC and/or short days, followed by increasing day length. Once reproduction has been triggered, Phalaris diverts energy from leaf production to stem and seed production. It is during the reproductive stage, that the tillers develop dormant buds. The further the plant progresses through the reproductive stage, the larger and stronger the dormant buds become.
The dormant buds allow Phalaris to survive the summer. Each bud is supplied with a trickle of moisture through summer by deep roots. Ensuring development of these dormant buds is critical to the persistence and production of Phalaris in the longer term.
Persistence of Phalaris also depends on soil type and environment. On lighter, more acidic soils, available Aluminium may restrict root growth, meaning that plants need to be carefully managed or the stand will not persist for very long. On heavier soils with higher pH and little to no available Aluminium, Phalaris may become dominant and heavier grazing can occur with little impact on the stand life.
With appropriate grazing management, weed control and fertiliser applications, a Phalaris based pasture will persist for a very long time. These pastures are productive, competitive with many weeds and are low cost, making Phalaris an ideal species for long term pasture situations.
This information has been summarized from the Evergraze More Livestock from Perennials program. Additional information can be found at www.evergraze.com.au.