Pasture recovery after fire

Improved perennial pasture paddocks previously sown to Ryegrass, Phalaris, Cocksfoot or fescues will need to be assessed a couple of weeks after substantial rainfall to determine the density of viable plants and the vigour of their growth. Perennial pastures can withstand a cool burn generally with minimal damage.  A cool burn will look dark brown in colour when looking down at the soil surface.

Some perennial pasture damage may occur under a moderate burn intensity – a moderate burn will be black in colour, but when you scrape the soil surface, will not penetrate far into the soil.  For perennial pastures affected to this degree, you can gently tug on any remaining plant material.  If it holds in the soil, it is likely the plant is still alive and should respond to any rainfall events.  If it pulls out with ease, the plant is dead.

Most plants will not survive a hot burn.  In a hot burn we often find the soil is burnt down into the soil profile, thus killing off the roots of the plants.  We often see a hot burn on the edge of tree lines, under hay bales that have burnt in the paddock or where there has been a large area of long standing grass.

Assessing plant populations are important, to determine the best option for pasture recovery.  Depending on the species and the number of viable plants per square metre decisions can be made to either re-sow, over-sow or rest the pasture to regain the plant density that you require.  A pasture with 20 plus perennial pasture grass plants per square metre will be able to regenerate into a productive pasture given favourable conditions. Weed incursion is also expected but can be managed with selective herbicides after the autumn break.

Perennial clover pastures can survive cool to moderate fire and drought, depending on the severity of the event and some clover species have hard seed that will remain in the soil for many months, and recruit over time. Annual clovers such as sub clover will have viable seed buried in the soil and will germinate following drought or a cool to mild burn, providing the soil has not been subject to a very hot burn.

Annual pastures that rely on seed set from the spring will be worst affected, due to the loss of seed.   Be prepared to reseed once the autumn break arrives. Alternatively, these annual pasture paddocks could be sown for winter fodder crops or grain crops.

Native perennial pasture, species such as Wallaby grass (Rytidosperma spp.), Redgrass (Bothriochloa macra), Kangaroo grass (Themeda triandra) and the valuable Weeping grass (Microlaena stripoides) are resilient to both drought and fire. After these events, these species will re-establish over time but need a rest period to fully recover and increase their bulk, allowing for ground cover to re-establish.

You may choose to assess pastures before rainfall events arrive.  If unsure whether a pasture has survived, you can use the watering can method.  Mark out a small area in the paddock of interest and water that patch each day and monitor to see if the plants recover or what might germinate.  Generally you should know within a fortnight the potential of that paddock.

At times it may feel all overwhelming and you are unsure where to start, but it can be beneficial to think about triaging your paddocks into a 1, 2 or 3 category.  Category 1 are paddocks that are clearly not going to recover without resowing – they might be your annual paddocks, or perennial paddocks less than 1 year old with a low density of viable plants, or paddocks that have suffered a hot burn.  Category 2 paddocks are paddocks that should come good with rainfall and rest, such as paddocks that have been affected by a cool to moderate burn.  Category 3 paddocks are paddocks that could be grazed now with minimal damage. It allows you to start planning what to do next, and allows you to start ordering seed for the paddocks that need it

Where extensive fencing has been lost and it is difficult to give pastures the rest they require, farmers should consider temporary fencing such as electric fending, or removal of stock on agistment or establishing a sacrifice paddock or stock containment area. Continuing to feed hay for a few weeks in a confined area will reduce grazing pressure on vulnerable pastures and will greatly assist in pasture recovery.

As the pastures begin to grow again with adequate moisture, don’t forget to apply nutrients where possible and as finances allow, to give them their best chance at recovery.

Details on how to build and manage stock containment areas is available from Agriculture Victoria offices or phone 136 186.