A serendipitous meeting with a Kiwi dairy farmer in France helped Jean and Dave Mansfield find a sustainable solution for their Waihi farm effluent.

“We were in France for our daughter’s wedding, wine tasting at a beautiful chateau when I saw a huge plastic bladder and asked what it was,” says Dave.

“When the farmer said it was for dairy effluent storage, I started asking questions and soon left the wine tasting with him for an inspection tour. That sowed the seeds of an idea for how to sort out our effluent issue.”

Best option

The Mansfields, who own an 86ha (70ha effective) dairy farm near Waihi have invested around $250,000 in a fully compliant effluent system, including $30,000 for a 300,000L storage bladder, supplied by Waikato Effluent and Environmental, formally known as Hi-Tech Irrigation.

“We looked at open ponds but found they had potential future health and safety issues especially for servicing equipment, and at large storage tanks, but finally decided the bladder system was the best option,” says Jean.

Extensive excavation work for the bladder site, laying of underground pipes and pouring of concrete for the new sump was completed by July, in time for the new season’s first milking on the farm which has been in Dave’s family for more than 100 years.

“The farm is two 100 acre blocks which were ballot farms taken up by Dave’s great uncles after World War I, and have been in the family, as sheep and beef and then dairy farms ever since,” says Jean, who describes the property as “one-third flat, one-third rolling and one-third steep”. With careful management, cows can graze on even the steepest paddocks.

“Caring for the land, the water and the wider environment has always been important to the family and we want to ensure it can continue to be farmed for the next 100 years or more.”

That’s why the couple, both in their 60s, decided to use money from selling Fonterra shares to invest in a futureproofed and environmentally sustainable effluent system. “Selling the shares made this possible. Most farmers can’t make that kind of investment from their milk income alone,” says Jean.

The farm, under manager Rod George, produces 70,000 kgMS from 200 A2 Jersey cows, and now supplies Open Country Dairy.

Sufficient storage

Before the extensive upgrade, effluent was irrigated onto pasture at nearly every milking. “Now I can choose how much, when and where to spread effluent – either directly from the sump when it’s not raining, or to the bladder for storage,” says Rod.

“It’s a simple system to operate and only needs attention once-a-week instead of daily. It’s taken a lot of stress out of the farm operation because we can store effluent and irrigate it onto 18ha compared with just 4-5ha under the old system. And there is no smell from the bladder,” says Rod.

While the system was expensive, there should be ongoing savings in potentially reduced fertiliser costs because effluent is spread over a wider area and in electricity bills with effluent stored in the sump pumped to the bladder using off-peak electricity.

Warick Buchanan, owner of Paeroa Farm Services which installed the system, says bladder storage is particularly suitable for the Mansfield farm, which experiences high annual rainfall. “As the bladder is enclosed, there’s no infiltration of rainwater. It also has one-third more capacity than required because Dave and Jean wanted to be sure there was sufficient storage for times when it can’t be spread.”

Sump and stone trap

Paeroa Precast Concrete installed the sump and stone trap adjacent to the herringbone dairy, which is also the site of the pumphouse, which drives the farm-wide system by sending effluent to pasture or the bladder.

Imported from France, with a 20-year guarantee, Warick says the bladders are very robust and constructed of materials designed specifically to handle effluent. While the system is relatively new to New Zealand, it has been in use in Europe for some time.

“From the word go, Jean and Dave wanted a fully compliant system done once and done properly and they have more than achieved that goal.”