Mar 1, 2005
Organic NZ Magazine - March/April 2005.Dr Tim Jenkins, of the Biological Husbandry Unit outlines strategies to develop great pastures
Grazing management can include a regular pattern of shifting livestock onto clean pasture. In some cases this may be as often as shifting each day. This is an effective way of ensuring good pasture diversity too, especially if paddocks can be left long enough for the more preferentially grazed and slower to recover species to recuperate from the grazing. This will involve a high level of permanent and possibly temporary fencing (with back fencing). (A further advantage of such fencing is to reduce losses of nutrients through dung and urine transfer – fewer stock camps etc).
The Holistic style of grazing management provides a framework for making the above ideas of grazing workable. (see www.succession.co.nz “Grazed and Confused” on lefthand side column)
Two of the basic methods of Holistic grazing management include not grazing a pasture too hard, and allowing good recovery of all desired pasture species.
1) Not grazing too hard
Grazing pasture lightly by just allowing access for one or two days (in some designs stretching to one week) will reduce the tendency for preferential grazing and the eating out of some favourable grazing species. If pasture is grazed too hard this can result in a loss of root activity and depth.
Moisture and nutrients are then more likely to be limiting to these shallow roots, lowering dry matter production, increasing seasonal feed deficits and resulting in poorer feed quality. With a poor root system, recovery of pasture takes longer and overall productivity will suffer. With good root systems on lightly grazed plants, general resilience is increased and legume nitrogen fixation is also improved.
2) Allowing recovery of species
Some desirable grazing species will take longer to recover than some of the main grasses. For this reason a decision on re-grazing based on conventional ideas of total dry matter measurements or height of pasture are likely to bias against the slower recovering species. It is therefore not uncommon to see chicory, plantain and other herbey components grazed out and outcompeted under conventional systems of grazing hard and not allowing full recovery of these species.
Regrazing time should be judged on when these slower recovering species have grown to a stage that one of their full leaves is dying – indicating a fully replenished root system.
Following these principles, a diverse, resilient pasture can be created and regenerated. The advantages of having diverse species present are manifold including tonic effects, reduced susceptibility to grass grub and other issues, less likelihood of pasture toxicity problems, and generally
improved animal health and performance.
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See www.bhu.co.nz for much new information from work supported by SFF and AGMARDT.
