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Published: 2008-08-04 00:00:00

After seeing the results for himself, dairy farmer and 2005 Waikato Sharemilker of the Year Mike Visser has no doubt effluent can be successfully used to grow maize – without any commercial fertiliser top-ups.

And it is set to save him hundreds, possibly thousands, of dollars a year in fertiliser costs.

Mr Visser is the regional chair of the AgITO Waikato committee, a Fonterra networker and a New Zealand Dairy Industry Awards committee member.

He talked about his experiences using effluent to grow maize at a recent workshop held at Gails of Tamahere last month.

The workshop was about trials on four different Waikato dairy farms, including the Ngahape property where Mike and his wife Sue sharemilk, just south of Te Awamutu.

The trials were set up by Environment Waikato and the Foundation for Arable Research (FAR) to find out whether maize could be grown in Waikato farm paddocks without using commercial fertiliser, and whether maize could strip nutrients from overloaded soils.  They were supported by DairyNZ and Genetic Technologies and part funded through a substantial grant from the government’s Sustainable Farming Fund.

Under FAR’s direction, the farmers grew maize on their effluent blocks using no fertiliser at all, to test whether nutrients already stored in the soil could produce a healthy crop.

To find out whether adding commercial fertiliser would boost yields, the farmers also grew plots using commercial starter fertiliser and/or side dressing.  Crops were sown last spring and harvested in February.

Presenting at the workshop, FAR project manager Mike Parker said there was “very little difference between the no fertiliser crops and the starter and side dressing crops”.

“Even though we had four different sites, four different management techniques and four different soil types, there was no difference in yield.  Fertiliser savings ranged from $233 a hectare upwards.”

He said while the trials had initially focused on high fertility sites, longer term the research team would look at whether effluent could also be used on lower fertility sites.

Mr Visser told the workshop his attitude to applying fertiliser had changed as a result of the trials.

“We always erred on the side of caution because if you’re a bit heavy handed it’s a lot better than having a poor crop,” he said.

“But there was basically no difference between the different treatments in our trial paddocks, which is pretty awesome, and it was a good crop, which was great considering it was a pretty tough year for growing maize.

“With current prices, the results showed $234-$460 per hectare worth of savings just on the starter and side fertiliser, but it should be remembered there was no base fertiliser applied either, so you add that on top and you’re starting to get some significant savings.

“It gives us a hell of a lot of confidence growing maize in the effluent paddock with no fertiliser.  I’d quite happily go in now and expect a good crop.”

Mr Visser said he had already extended his effluent area and was now saving pond scrapings and calf shed bedding to spread on paddocks.

Asked by an audience member if he could see any difference with new grass coming through the maize paddocks, he said there was none at all.

“It’s a fantastic looking paddock,” he said.

He emphasized the importance of testing nutrient levels in soils before applying effluent – or any fertiliser – to paddocks.

“Even at $90 for an effluent test, that equates to about a 50kg bag of DAP, so that’s not a bad investment really.  Probably half the guys you’d talk to wouldn’t have any idea of the application rate from the effluent spreader – most just put it on and if it looks enough, it’s enough.

“There’s probably a mindset out there that it’s more important to comply with Environment Waikato regulations than it is to get the most out of your effluent.  But it’s a resource that’s sitting there and we’re just discovering now how we can use it to save some money along the way.”

Following steep rises in fuel, feed and fertiliser prices recently, Environment Waikato sustainable agriculture coordinator Gabriele Kaufler said the trial results were good news for farmers and the environment.

“This leaves more money in farmers’ wallets and helps to strip out nutrients from soils which would otherwise wash through into rivers and streams and contribute to pollution problems in waterways,” she said.

Also speaking at the workshop, DairyNZ developer Debbie Care said she’d had a lot of calls from farmers interested in effluent as a nutrient source, because of rising fertiliser prices.

She likened nutrients in the soil to money in the bank that could save farmers hundreds of dollars per hectare, but highlighted the importance of soil testing.

“Do some research about what’s in your bank,” she said.

Speaking after the workshop, Wharepapa South maize grower Alan Ramsey said he would consider buying effluent from farmers to feed his crops if the price was right.

“The cost of fertiliser has got so high these things are worth it,” he said.