Environment Waikato's sustainable agriculture facilitator Gabriele Kaufler promised the first 500 farmers to have their herd's effluent tested would be billed $85 instead of the normal $102.

Farmers can save money on fertiliser by using effluent produced by their dairy herds in its place.

Ms Kaufler said testing by a lab was necessary to help farmers avoid overloading soil with the likes of potash, which can cause animal health problems.

"Once farmers know their effluent's nutrient value they can calculate how much they should be applying for optimum pasture growth and how much money they can save by reducing the amount of bagged fertiliser they buy," Ms Kaufler said.

The regularity of testing will depend on the system each farmer is running and the feeding regime of cattle.

"If they are fed a lot of supplements in the spring and around calving they will need testing then as well as when they are fed on pasture alone," Ms Kaufler said.

Source: Waikato Times