5.6.2019 Spread lime

How does prilled lime fit into soil acidity management?

Are prilled lime products effective in soil acidity management?

Agricultural lime itself is cheap ($20 to $40/t) but transport costs is what makes liming expensive and is the main driver in its’ cost spread. Transport costs are about 10 cents/ton/kilometre.

The attractiveness of prilled lime is that if used at low rates (600 to 800 kg/ha), then the cartage costs of lime transport are far reduced. However, savings in transport will be eroded by the higher costs of the prilled superfine lime at $300 to $600 per ton.

The reason the cartage costs are reduced is because prilled lime is commonly advertised to be applied at one third of the rate of agricultural lime. This means that the carbonate concentration which neutralises the acidity is also reduced to one third. This is an issue, if trying to ameliorate an acidic soil. If trying to maintain good soil pH, this would not be such an issue.

The soil contact of the pellet will also reduce, so there is more soil that will not get any lime.

But while there are downsides to these products, there has been success using these products down the sowing tube to ameliorate soil acidity in the sowing row (Price et al, DPI, NSW) and in the subsurface layer at 10cm-15cm (Hughes, PIRSA) and that is where these products have a place.

Published research findings regarding prilled lime can be found in the 2021 SFS Trial Results book.

There probably is little advantage in using prilled lime on non-arable land. You could equally apply low rates of agricultural lime aerially or spread lime on a windy day from arable areas. Acidification rates of non-arable areas are likely to be low, in line with production levels which means they either need low rates of lime or often it is just not cost effective to lime them.

One way to combat high transport costs, is to access lime from the closest lime quarry. It might be cheaper to apply a higher rate of lime, than cart further from a lime quarry with higher Neutralising Value.

The LimeAssist calculator contains a nifty tool that calculates the lime rates and cost spread based on the lime you chose from a dropdown box or map to your property which makes comparisons between limes easy. Access is from the My Farm Dashboard.

Tools and calculators My Farm Dashboard (sfs.org.au)

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