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Published: 2009-06-10 00:00:00

Testing the nutrient content of farm effluent and applying the data gained is a key way to help the dairy industry hit productivity targets, says regional council Environment Waikato.

“Farming’s an increasingly hi-tech business and the data gained from testing effluent is a logical way of boosting productivity and profits, as well as protecting the environment,” says EW’s sustainable agriculture coordinator Gabriele Kaufler.

“The fact is that not enough farmers are using effluent testing and are therefore missing out on its potential to help their bottom line and protect our natural resources.”

Land application of effluent is recommended practice for dairy farming as it enables the nutrients to be recycled back into the farming system, reducing fertiliser spending and improving soil fertility.

But to be able to reap all the benefits farmers need to know the nutrient content of their effluent, says Ms Kaufler.

“Farm specific effluent testing will enable farmers to understand the fertiliser value of effluent on their farm.”

By adjusting the application rates to meet pasture or crop requirements, utilisation of effluent nutrients will improve, and animal health issues, for example from potash overload, will be reduced. Also, negative effects on the environment from nutrient run-off or leaching can be avoided.

The nutrient content of dairy effluent varies greatly depending on stocking rates and the amount of supplements used. Day-to-day management practices like yard or feedpad wash-down and cleaning routines, as well as the frequency of yard use as a stand-off facility, influence the amount of effluent collected but also the nutrient concentration in effluent.

Effluent storage systems and the way they are managed will also determine how much of the nitrogen content will be lost into the atmosphere. The local weather conditions and stormwater entering the system are other factors to take into account.

“So it is essential to analyse the nutrient content of effluent in order to be able to manage this nutrient source most effectively. Applying effluent to land without sampling is a stab in the dark,” says Ms Kaufler.

She says effluent sampling is basically easy. It requires the farmer to put containers out under the irrigator and collect a lab sample. It is important to record the application depth in each container before emptying them into the sampling bottle provided.

Sampling kits are available from any agricultural lab and farmers can order them like ordering soil or herbage testing equipment.

Environment Waikato has developed the sampling kits and a sampling instruction sheet with Hill Laboratories Ltd. Also, a user-friendly nutrient report was created which states the nutrient content as kg of nutrient per cubic metre of effluent. This enables farmers to easily work out the nutrient loading rates from the recorded application depth under their irrigator.

Feedback on testing from farmers has commented on the improved understanding they get and on how they are able to adjust effluent application focusing on nutrient utilisation, with the associated benefit of reduced fertiliser spending.

“Sampling is a prerequisite of sound nutrient management on every dairy farm, with the added benefit of cost savings and improved animal health. It will also contribute to avoiding environmental risks associated with nutrient overload, run-off and leaching from the effluent block,” says Ms Kaufler.

Environment Waikato and Hill Laboratories are currently exploring other opportunities to help to take effluent nutrient management to the next level.