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Published: 2008-08-18 00:00:00

Waikato farmers would best protect the environment by keeping effluent irrigators switched off until local soils have had a chance to dry out, says sustainable agriculture coordinator Gabriele Kaufler.

She was commenting following reports of farmers continuing to use effluent irrigators, despite soils being soaked as a result of prolonged rain in the region, because they don’t have enough effluent storage available.

"Irrigating effluent while soils are saturated is a breach of the council’s permitted activity rules. This is because the effluent will pond and there is a huge risk of effluent running into waterways while soils are very wet."

Ms Kaufler said the purpose of irrigating effluent is to enable the soil to treat the effluent and to absorb the nutrients. "This is unlikely to occur if the effluent gets washed through the soil by heavy rainfall events. Farmers lose a lot of money when irrigating on wet soils as the grass can't utilise the nutrients.

"It is only safe to start using effluent irrigators again when there is a soil moisture deficit. Until then farmers need to be able to store effluent. If there is not enough storage at hand, it is important to plan now to get storage installed this summer. Normally two to three months of storage is adequate unless you are in a high rainfall area. As we all know, winters are wet and there is quite often a prolonged period of time when irrigating effluent simply can't occur.

"When you start irrigating again, please make sure you put on very small amounts of effluent. Stay well clear of any waterways and drains. Do not irrigate on land with subsurface drainage like mole and tile drainage because this will take the effluent straight through to the waterway.

"Low rate application systems are easier to manage when soils have a high moisture content but, again, they can't be used on saturated soils either.

"In the meantime, we ask farmers to be patient and to manage their effluent carefully."

Anyone wanting further advice on the rules can call Gabriele Kaufler on 0800 800 401.