Take a leaf out of the plant physiology book
Published 20/09/2011 | 05:00
Autumn should ideally allow pasture cover to build and offer the opportunity to extend our grazing season. However, recent weather conditions have resulted in a mixed bag of on-farm situations. This is ranging from heavy soils being water logged, to areas with good grass growth resulting in a substantial increase in pasture cover with minimal supplementation. In contrast, other farmers are unable to build up or hold the present cover as a knock-on effect of dry conditions.
As a result, no one solution fits all and you will need to regularly walk and determine your pasture cover to review your present decisions and make any necessary change this autumn.
The aim must be to balance both the requirements of the cow (feed demand and condition score) with those of the pasture plants.
Understanding plant physiology may assist you with your decisions this autumn. Perennial ryegrass plants consist of a number of tillers connected at the base.
Each vegetative tiller is able to maintain three live leaves and as the fourth leaf emerges, the oldest leaf dies. Immediately after grazing, the growth of the roots and of new tillers stops and the tiller uses stored water-soluble carbohydrates (WSC) to grow leaf one.
Once tillers have grown between half and one full leaf, roots begin to grow and plant begins to store WSC.
As a result, pasture growth immediately after grazing is slow, and between grazing and the one-leaf stage (second leaf emergence), only accumulates approximately 15pc of total pasture yield. Growth of the second leaf to the two-leaf stage (third leaf emergence), allows new tillers to grow and growth accumulates more rapidly to 35-40pc of total pasture yield.
From the two-leaf stage to the three-leaf stage WSC reserves are replenished to pre-grazing levels, and growth will account for 45-50pc of total pasture yield. As the fourth leaf grows, sensence (death) will start to equate to growth, and tillering will reduce with an increase in stem formation as tillers receive reduced light penetration to the base of the plant.