They could be described as the excrement dream team.
On the one hand, you have the brains of soil scientist and urine aficionado Dr Bert Quin, who set up the fertiliser co-operative Summit Quinphos.
He says his interests throughout his career are the two Ps: pee and the P in phosphorous.
Then, there's engineer Geoff Bates, whose many inventions include the Dung Buster, which is used to clean up milking yards.
The Auckland men met about two years ago, but in that short time they have discovered they have the same passion - cleaning up waterways.
The pair will show off their invention - a urine-detecting robotic trailer - at the NZ National Agricultural Fieldays 2015 which kicks off tomorrow at Hamilton's Mystery Creek Events Centre. This year's event features a record 1426 exhibitions and organisers hope it will attract more than 120,000 visitors.
Dr Quin said nitrogen, in the form of nitrate leaching through urine patches, was possibly the country's most serious environmental problem.
"Up until now, there has been no way of finding the urine patches."
So, the pair came up with Spikey - a robotic trailer that detects patches of cow urine then slices it up, spreading it out laterally and preventing grass deterioration. "More grass equals more milk which equals more money. So instead of losing money, the farmers are actually making money out of it," Mr Bates said.
The process could also be combined with other operations, including the spreading of fertiliser.
The pair are in the grass roots section of the Innovations section of this year's Fieldays, which is set to be the biggest one yet.
Fieldays communications executive Rachel Middleton said 70 new sites had been added because of redevelopments, including the filling in of the lake and the creation of the central precinct which will feature the "big players" of the primary sector.
Another new addition was the Innovation Accelerator - an invitation-only space where 10 exhibitors from previous Fieldays will explain what they are up to now.
Heritage Village will depict farming in the Victoria era.
Another creative couple in the grass roots Innovation section are engineers Roland and Melanie Phillips, who will showcase their mobile mini milking machine developed to milk their small herd.
Originally they were milking by hand and realised how tough it was. So they designed their contraption and Mr Phillips built it.
"This addresses firstly the growing demand for milk direct from the farm gate and also the technical issue of getting a farm's dairy premises into and around urban areas for retail convenience," he said.
Fieldays weather
Tomorrow: Cloudy patches with possible showers, 17C
Thursday: Showers likely in morning, 15C
Friday: Scattered cloud and showers, 14C
Saturday: Cloud chance of isolated shower, 14C