When he bought his Queensland cattle property a decade ago, Peter Kenny knew the eroded gully that snaked through his land would give him trouble. And it did, growing with the annual flood waters until it was 100 m wide in places, and 5 m deep. "Every year it would creep further towards the road," he says. "I wondered what the hell I would do about it."
Erosion devours riverbanks, strips hillsides and eats out gullies. Across the Australian continent, soil is being lost faster than it's being replenished. And when it enters waterways, soil sediment chokes them, smothering plant and animal life. Last week's release of the first national assessment of waterborne erosion shows how grave the problem is-an average 4.4 tons per hectare are lost every year from agricultural lands and 14 million tons of soil are washed down to the Queensland coast alone. There, brown plumes up to 20-km-long flow into the sea, carrying a soup of nutrients and pesticides that threatens 200 coral reefs close to the shoreline. Nutrient loads are rising, says Sheriden Morris, water quality director at the Great Barrier Reef Marine Park Authority, affecting the corals' ability to reproduce. Result: "You get a reef in decline."
The National Land & Water Resources Audit report found that the continent's pattern of erosion has accelerated greatly in the past two centuries, with almost 4.5 billion tons of soil lost from gullies alone since European settlement. Sediment loads in agricultural area catchments are up to 15 times the natural level.
But the report also offers a recipe for tackling the scourge. Agricultural practices are critical, but though they're improving in many places, questions remain about who will pay to repair and protect individual properties. "There's nothing in the market that drives a farmer to necessarily worry about what happens off his farm," says Audit executive director Colin Creighton. That's where the burden could be shared, especially since, Creighton says, "we in the cities are expecting the few people who manage 60% of the landscape to deliver quality water, nice landscapes for us to drive through and lots of biodiversity."
At Peter Kenny's place, volunteers from Landcare and the local council have helped him fill in the 100-m-long gully. Now it's a flat stretch of grass. "We understand that the top two inches of our soil is our bread and butter," Kenny says. "What we need to do is all look at one another's problems as being our own."