Fire damage to pastures & erosion risk

After a fire, a prolonged dry period of months may occur before adequate rain triggers pasture re-growth, or heavy rainfall may occur in the weeks following fire. Heavy rainfall can cause substantial topsoil loss from burnt pastures, and can lead to dangerous mud slides causing further damage. Erosion can be particularly problematic in gullies and where it washes soil and rocks into paddocks covering new pasture growth. Strategies to manage erosion risk are outlined on pages 38 and 39 of the ‘Recovery from fire guide’ from Agriculture Victoria.

While awaiting pasture regrowth, consider managing stock in containment areas to avoid grazing bare paddocks which can lead to topsoil erosion. When regrowth occurs, challenges in utilising this pasture include being understocked, having incomplete fencing, and the presence of health risks to your animals.

Plant toxicities were one of the most common animal health issues reported in producer interviews following the Black Summer bushfires. Pastures that are regrowing vigorously after being burnt (such as kikuyu, phalaris or lush clover) can cause health issues in stock as they have little or no dry standing feed as an alternative for grazing stock, increasing the risk of toxicity. As pastures begin to recover, utilise them cautiously, with precautions such as:

• never introducing hungry stock onto a possibly toxic pasture
• reducing the area of new pasture available to stock (e.g. with temporary electric fencing)
• providing access to alternative feed such as hay or straw to reduce pasture consumption
• keeping a gate or fence line open to access standing dry feed in another paddock, if available.

Weeds post-fire are a common problem, driven by a combination of reduced pasture coverage, fire-activated growth and spread of weed seeds during fire response (e.g. by earthmoving or fire trucks). Identify the weeds that occur on your farm to determine whether they pose a risk to your stock and control them before grazing to support pasture production and reduce animal health risks.