I frequently hear graziers talking about planning for a long rest period (e.g. 12 months). The reasons are varied. For some it is Sabbath rest (religious basis), seed set, fuel load accumulation, post-fire recovery, production reasons (e.g. for weaners), and some heard it was a good idea and it will help the country.
When considering whether to give paddocks a long rest period, you’ve got to consider two things:
- The reason you want to do it, and
- Plant physiology/ecology
A few reasons are mentioned here. What you really need to clarify is the outcomes you hope to achieve from a long rest.
Plant physiology and ecology
Let’s revise the three phases of growth a perennial grass goes through (diagram below).
Phase 1 – slow growth and poor root systems (low quantity/high quality)
Phase 2 – fast growth and developing root systems (increasing quantity/decreasing quality)
Phase 3 – slow growth, lignification and diminishing active root systems (high quantity/low quality)
When does a perennial grass go to seed? It depends on the stress that plant is under. Therefore, it has the potential to go to seed in phase 1, 2 or 3.
Do we need to increase the amount of seed in our systems? In most cases, no! Unless it is an introduced species not native to the area, chances are there is plenty of seed present… they just need the right seed bed and conditions to grow.
Seed bed and plant succession
Remember talking about state and transition/plant succession at the RCS school? (if not it may be time to do it again!) Put simply, mother nature repairs bare ground by sending tough, undesirable, pioneer species with hard tap roots into battle first.
Once they’ve done their job opening up the soil and pumping some sunlight energy into the system, the next stage of succession starts. The broad categories are bare ground > weeds > annuals > undesirable perennials > desirable perennials (as shown in the diagram below). The key aspect of each stage of succession is the root systems. Desirable perennials have deep fibrous (soft) root systems. The better the root systems, the better the soil and seed bed, the better species of grass with grow.
Now, in what phase of growth do we have the best root system?
Phase 2. In phase 2 we have a plant that has a strong, active root system and plenty of green leaf photosynthesizing above the ground. The digestibility and quality is good and the plant is energy efficient.
The photo below shows the three phases of grass under differing management systems. It is obvious that phase 2 grass is the most robust both above and below ground.
Long rest periods lead to phase 3 grass (provided there is enough moisture and warmth). In phase 3 we have more lignified, poor quality grass and a shrinking active root system. Lignin = less animal production and less roots = poorer ecosystem.
Just how attractive is the long rest after considering these facts?
Does it meet your outcome and is it best for plant physiology? I’m not saying don’t give paddocks a longer rest every now and then, however, I believe the variations of the conditions you have to manage will naturally result in some paddocks getting that rest at times out of absolute necessity, rather than as a result of planning.
I’d focus on accumulating as much phase 2 grass as possible during the growing season, then with a maximum of two grazing events during the non growing season – leave them ready to explode next wet!
Article by David McLean
RCS General Manager