Farmers urged to be aware of hungry hay

Farmers urged to be aware of hungry hay


Grain
Farmers are being urged to monitor nutrient levels following hay crops.

Farmers are being urged to monitor nutrient levels following hay crops.

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Hay has been a useful tool this year, but farmers are warned they will have to closely monitor nturient levels for next year.

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HAY has played an invaluable role in allowing farmers to manage the drought this season.

Faced with crops struggling with moisture stress many farmers took the decision to cut for hay and with sky-high hay prices have managed to generate gross margins on par or better with those that could have been expected from grain.

However, apart from the time taken to produce the hay and the higher costs, such as cutting and baling, nutrition experts are warning there is a hidden cost.

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Agriculture Victoria research scientist Roger Armstrong said farmers needed to be aware of the extra nutrients a hay crop took out of the soil and plan accordingly for next year.

Cutting hay removes significantly more nitrogen, potassium and sulphur than if the crop was left standing for grain production.

Research supported by the Grains Research and Development Corporation (GRDC) found hay can remove up to two times more nitrogen and up to 10 times more potassium than if the crop was harvested for grain.

In canola, up to five times more sulphur can be lost.

Dr Armstrong said one-off 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.

And soil pH can also be upset.

Dr Armstrong said 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 45 kg/ha for each tonne of annual legume hay removed, to neutralise the resulting acidity.

Cutting hay 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 might be roughly similar to organic matter lost from burning stubble residues from a good crop, compared to retained stubble.

A lack of soil cover post-harvest is also something that growers need to consider, potentially limiting their grazing options.

Following hay cutting, little residue cover (maybe 0.4 t/ha of residue after hay cutting versus 2.0 t/ha after harvest) remains.

Growers are therefore advised to reduce grazing and traffic across these paddocks to minimise the risk of wind and water erosion which also contribute to soil nutrient loss.

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