Boosting Crop Production by Spreading Effluent
Tararua district farmer Jamie Harris milks around 400 cows using a split calving system on his farm, Crossdale Dairies.
A farm dairy effluent system must collect all animal excreta deposited in contained areas, plus any other liquid or material coming into contact with it, says system designer Numedic.
Not just the milking shed, but any stand-off areas, feed pads, housing areas and stock underpasses where effluent collects, must be serviced.
The industry’s calculated average is 70L/cow/day. But Numedic director Catherine Reid says this figure includes an animal manure component of only 10L/cow/day; the other 60L is mostly water from washdown, backing gates and cleaning.
“If we can reduce this volume of water we can lower the cost of electricity used in sourcing the water, using it in the cowshed and pumping it as effluent,” says Reid.
To reduce the volume of effluent needing to be pumped or stored requires finding ways to improve water use efficiency.
One such way, the company says, is its Hydrofan washdown nozzle. In an average size herd of 400 cows the nozzle can save 1.2 million litres of water per year.
“This automatically also means power savings so farmers can keep more money in their pockets,” says Reid.
The ‘secret’ of the Hydrofan nozzle is its patented water jet orifice and angle which improves water efficiency and mostly is faster in yard washing. The nozzle produces a sharp, stable stream with high impact using less water.
Nozzle trials by Northland Regional Council have shown 20-70% in water savings, Reid says. More trials are now underway on South Island farms jointly with Environment Canterbury.
“The general feedback from users is that the nozzle also achieves the yard washing faster,” Reid says.
Numedic is an accredited designer of farm dairy effluent systems.
Tel. 0800 686 334
Entries opened on Monday, 5 October 2026 for the 2027 New Zealand Dairy Industry Awards (NZDIA), which organisers describe as the nation's biggest celebration of excellence in the dairy sector.
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