Scientists in New Zealand believe leaching of nitrogen from cow urine patches is one of the most serious threats facing their grazed dairy farms.
Farmers down under have long used dicyandiamide (DCD) to slow down nitrate leaching, but it was removed from the market in 2013 after traces were found in exported dairy products.
Now, their search for a urine patch solution has delivered a robot called Mini-Me, which identifies urine patches after each grazing and immediately applies products to reduce nitrate leaching.
The machine developed by Dr Bert Quin and Geoff Bates of Pastoral Robotics moves over a paddock in a pre-programmed route, scanning as it goes and making applications where necessary.
It sounds more promising than another company’s device fitted to cows, activated by the cow raising its tail to automatically treat urine patches.
Mini-Me can be put into action immediately after cows leave a paddock, unlike some other automated devices which depend for urine patch detection on the urine patch grass growing and changing colour.
Immediate use also reduces the risk of another DCD-type contamination of dairy products, because it will be at least 28 days before pasture is grazed.
The 50kg Mini-Me robot travels at 5km/h or less, covering 1.5 hectares per hour, adequate to cater for a 600-800 cow herd.
The farmer intervenes only to move the robot to each new paddock, change the rechargeable batteries, and top up the spray tank.
The aim is to apply environmentally-safe products to reduce nitrate leaching by at least 75% (urease inhibitor and grass growth promoter are now favoured over DCD).
Large New Zealand dairy farms were often spending €6,000 per year applying DCD — which indicates the need for a technological solution.
Mini-Me prototypes have used spiked metal wheels to detect urine patches with a high degree of accuracy.
But non-contact detection technology has also been developed.
With a view to launching the machine on the market as soon as possible, Pastoral Robotics are looking for angel-type investment to build a six-metre wide all-weather version.
They believe it could sell overseas also. In Ireland, Teagasc research has indicated application of DCD to urine patches occasionally increased herbage production, but results were inconsistent.
But researchers agree there is a high risk of nitrate-N leaching losses from urine patches deposited by grazing dairy cows (which can have over 800 kg per hectare of nitrogen, in equivalent terms to applying artificial fertiliser).
Dairy cows leave a urine patch about every grazing hours, according to Teagasc researchers.
This equates to 14-21% of the soil surface being wet by urine annually, at stocking rates of 2.0 to 2.94 cows per hectare.
In New Zealand, commercialisation of Mini-ME could open up a host of additional on-farm uses for robotised technology, including soil fertility and moisture assessment, pasture and crop growth and quality assessment, precision application of nutrients, trace elements and other pasture additives.
Bigger versions may even replace slurry spreaders.
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