Make hay, lose potassium

AS YOU drive around, headers and chaser bins are operating in average crops but the other thing you see is many of us making hay bales.

For the landowner with this year's expected one-to-two tonnes of cereal hay baled per acre and sold off, it is another source of income to bolster finances. From local hay sales, the income from this recently harvested wheat and barley is about $100/tonne. But apart from the cost of baling, what is the future cost of nutritional and agronomic loss from your hay going out the gate?

There is no dispute this form of fodder is necessary for livestock producers in the grip of this dry time and their capacity to pay is diminishing weekly.

There is no doubt retaining stubble is necessary for future agronomic reasons. I acknowledge baling stubble from header windrows is better than burning or cultivating a paddock but we all know stubble is king for fallow soil water storage efficiencies.

On the flip side, with the explosion of residual fallow herbicides like Flame/ Impose, Balance and metolachlor/ atrazine mixtures, great clumps of stubble are not so desirable for these herbicides to be soil colloid attached to ensure effective weed control. As for nutrient removal in the hay, my assump- tion is hay bales are made up of more than 50% plant stem material and that probably has the lowest nutritive value compared to leaf blades and sheaths. From research figures, you can determine about 4kg of nitrogen, 1-2kg of phosphorus and, surprisingly, a 8-10kg of potassium will be the main nutritional elements in a tonne of stubble hay. Unless you are regularly adding bio- solids or manure to your paddocks, it's a certain bet you are depleting an already under-pressure element in potassium.

There's no way I will advise people not to sell stubble hay from their paddocks. All I will advise is that future nutritional inputs may need increasing and our capture and percentage retention of summer rainfall events bears watching and physically assessing before any intended seeding event.

Oh and by the way, I'm against cultivating in 2013 winter crop ground as, with some cracks two inches wide and quite deep, what better way is there to get rain run-off into the soil profile?

Topics:  paul mcintosh soil health

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