Cutting failed crops can cost nutrients in soil
NORTH East growers who have this year cut crops for hay and silage are being reminded that they have also removed considerable nutrients from their soil.
Crop nutrition experts - supported by the Grains Research and Development Corporation (GRDC) cantly more nitrogen, potassium and sulphur than if the crop was left standing for grain production.
According to research, hay can remove up to two times more nitrogen and up to 10 times more potassium than harvested grain crops.
sulphur can be lost.
Agriculture Victoria research scientist, Roger Armstrong, said oneoff hay cutting of a failed crop can prompt changes in crop nutrition programs and paddock management into the next season.
“With nutrients that would otherwise be recycled in the soil being lost through the removal of crop material in hay and silage, soil tests will become more important ahead of next year’s sowing to inform nutrition programs in 2019,” Dr Armstrong said.
Dr Armstrong says repeated removal of hay is considered to be one of the most acidifying of agricultural practices, and on acid soils can exacerbate the issue in the longer term.
The removal of cereal or canola hay requires 25 kilograms/hectare of lime for each tonne of biomass removed, or 45kg/ha for each tonne of annual legume hay removed, to neutralise the resulting acidity.
Cutting hay also reduces inputs of organic matter into the soil for that season.
The size of the effect when the hay is cut from a failed crop can be roughly similar to organic matter lost from burning stubble residues from a good crop, compared to retained stubble.
Following hay cutting, little residue cover - around 0.4t/ha of residue after hay cutting versus 2.0t/ha after harvest - remains.
Growers are therefore advised these paddocks to minimise the risk of wind and water erosion which also contribute to soil nutrient loss.
To support growers and advisers wishing to access tools and re- sources to assist with dry season decision-making, and for general support, the GRDC has developed a “Dealing With The Dry” web portal which contains links to useful information.
Information on nutrient removal from cutting crops can be found on the GRDC Communities website at http://bit.ly/2qyUCre and http:// bit.ly/2DByOnz.
THINK BEFORE YOU CUT: Cutting hay removes significantly more nitrogen, potassium and sulphur than if the crop was left standing for grain production.