Whey as fertiliser

Press, 13 March 1987, Page 19

Whey as fertiliser

For farms located close to a dairy factory, whey is cheaper than conventional fertilisers and contains similar amounts of nutrients, according to the Dairy Research Institute.

In recent trials, whey applied at a typical rate of 40,000 litres a hectare achieved comparable results to other normal fertiliser applications. Rhododendron plants treated with both cheese whey and chicken manure were significantly taller than those receiving the conventional fertiliser, potassic superphosphate. Dairy Institute researchers said farmers could save $10.5 million a year by replacing conventional fertilisers with non processed whey.

But because fuel and labour adds to the cost, contractors are reluctant to cart whey further than 10 kilometres from the dairy plant.

Whey is separated from curd during casein and cheese manufacture. It is the main byproduct of the dairy industry, and in the 1985-86 season, 2.7 million cubic metres were produced.

Last year 41 per cent of non-processed whey was used to fertilise 18,000 hectares of farmland throughout the country. “Commercial whey distribution operations could be very profitable for contractors,” the researchers said.

If contractors bought a new truck for spreading, the estimated rate of return is 45 per cent. If a second-hand truck was bought, the rate of return would be about 142 per cent.

Whey can be applied to several farms at typical rates using a truck with a tank containing 6000 to 11,000 litres. Soft soils such as peat may require smaller tank sizes of 6000 to 8000 litres. Trucks can be fitted with high flotation tyres to avoid pasture damage from wheel tracks when the ground is wet. Gravity feed, vacuum or pump discharge systems can be used to apply whey evenly.

On difficult terrain, a tanker can cart it to a mid-steer tractor which can then tow a 7000 litre vacuum spray tank for application. Wet weather can delay distribution, but whey can be stored on farms in open clay pits using copper sulphate pentahydrate as a low-cost preservative.

Preserved whey can then be applied to pasture when conditions permit.