SOIL erosion management promises to be high priority for drought-impacted grain growers in New South Wales battling the effects of diminishing stubble cover on fallow cropping country.
The run of dry weather has forced some growers to graze failed crops and cut crops for hay, resulting in less-than-ideal stubble loads in some paddocks and heightening the risk of wind and rainfall erosion.
With many growers yet to receive useful falls of rain, summer crop planting has been limited to date and growers are weighing up their erosion management strategies in case planting opportunities don’t arise before next winter.
While the state’s cropping soils vary in susceptibility to wind and water erosion due to type and topography, the Grains Research and Development Corporation (GRDC) is encouraging growers to actively monitor stubble and soil status through spring and into summer.
Over the years, GRDC research has backed up the rule of thumb recommendation that growers, and particularly mixed farming operations, should aim to retain at least 70 per cent ground cover (or about two tonnes per hectare of cereal stubble cover) over summer to ensure crop yields are not affected next year.
However, with stubble loads in drought affected areas now likely to be well below that 70 per cent benchmark, GRDC manager agronomy – north, John Rochecouste, said growers should aim to maintain current soil conditions.
“In these types of situations, it’s important to minimise any activities which will further expose the surface and make it vulnerable to erosion, such as grazing,” he said.
“If the situation becomes desperate, growers can consider a strategic cultivation to curb erosion and maximise water infiltration, although the suitability is very dependent on slope and implement choice.
“At the same time, it’s very important that any cultivation leaves the surface coarse and lumpy to slow runoff and reduce soil surface wind speed.”
While some growers may question the longer-term implications of strategic tillage, a GRDC investment into its use within conservation farming systems found that although tillage damages soil structure, when it’s used as an occasional strategic option the effects are not long-lasting.
Researchers found that recovery time varied between one and four years, depending on the type of tillage and subsequent rotations with soil structure returning more quickly to its pre-tillage state following a pasture phase.