Bushfire recovery: start with the soil

Some burned soils form water-repellent crusts, others lose structure and wash away, removing nutrients and polluting watercourses. Deep ash makes growing conditions too alkaline: in home gardens it’s better to remove excess (shovelling or raking) before adding organic matter. 

Incorporating 10cm of organic matter rebuilds soil life and increases water holding capacity. Adding gypsum to clay, and bentonite to sand, improves structure: liquid Eco-flo Gypsum or Plant Doctor’s Micronised Gypsum Liquid are easily applied to beds you can’t dig. Humic acid (not detergent) organic wetting agents, such as Eco Hydrate or Plant Doctor’s Natural Soil Wetter, will reduce water repellency. Liquid seaweed extract and/or worm juice support soil life; apply as you can. You may be reluctant to mulch after fire so assess conditions, but a thin layer of coarse organic mulch, or even gravel, reduces wind and water erosion. If you’re too busy to incorporate compost, just mulching helps. 

Don’t worry about early weeds: they stabilise soil and restore microbial life. Or you can scatter an attractive mixed manure crop, such as bee or cottage mix – healthier for soil than monocultures! 

You needn’t tackle the whole garden immediately. Whether your slate is clean or partially erased, the next few years are ideal for reconsidering design elements to improve your garden, incorporating surviving plants and structures (or not). Consider lawns, deciduous trees, fire retardant ember screening shrubs, or bushfire sprinkler systems. 

• To check soil contamination, Macquarie University offers a $20 testing programme: research.science.mq.edu.au/vegesafe/how-to-participate/

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