New technology reduces nitrogen losses from dairy farms
Technology developed in New Zealand by Pastoral Robotics Ltd has enabled the detection and treatment of fresh urine patches in pasture to reduce losses of nitrogen to the environment, promote grass growth and increase milk production. Early on-farm development, supported by the New Zealand Agricultural Greenhouse gas Research Centre (NZAGRC), led to AGMARDT supported research into further trials. That resulted in a farmer consortium in the Bay of Plenty to take up the technology, involving a machine called Spikey®.
Leaching of nitrate-nitrogen (NO3-N) from cow urine patches is a serious threat facing the viability of grazed dairy farms in New Zealand. The challenges are both environmental and economic.
Proposed solutions to the problem have largely focused on changing the basis of the year-round grazing model. Most of these require increased capital expenditure (and ongoing maintenance costs) on barns or stand-off pads, and capital and running costs to collect and re-distribute manure.
Chemical solutions have also been considered. Nitrification inhibitor DCD (dicyandiamide) used on pasture is now off the market after concerns were raised about resulting chemical residues in milk.
Other solutions that permit full-time grazing have been focused on better matching energy and protein ratios of feed to a cow’s intake requirements, through different plant species or mixes of crops and pasture.
But the team at Pastoral Robotics took another approach - was there a way of treating urine patches in-situ, mitigating urine load on the soil, while making more N available to promote pasture growth?
The AGMARDT funding allowed Pastoral Robotics Ltd to undertake three pilot trials of a treatment system called ORUN on farms in different regions (Canterbury, Manawatu and Rotorua). The trials led to the first farm system sale to a consortium of farmers in the Rotorua region. The trials added to the depth of knowledge and led to siginificant refinements in the system.
Geoff Bates, co-founder and managing director of PRL, said the seed funding grant allowed the company to progress the business and prepare for the next stage in their research and development program. (AGMARDT Annual Report 2016/17)
Early experiments suggested the most easily identifiable traces of urine deposits were found to be changes in surface soil moisture and conductivity. Cows’ urine is high in potassium, sulphate and chloride, all of which are charged particles (cations or anions) that impact on soil conductivity.
The spiked discs (that give Spikey® its name) measure soil conductivity when they make contact with the surface soil while being towed over a paddock. It sends a signal to an on-board processor for interpretation. When fresh urine patches have been identified they are targeted for treatment.
Conductivity is most easily measured when the soil is moist, so to improve accuracy under dry soil conditions, soil surface resistivity is also measured. The unit has an 8m wingspan that can be folded up for easy relocation to another paddock or property.
Geoff says the detection technology is robust. “It rarely misses a urine patch and the only false positives we get are from fresh cowpats. We can filter them out with the technology if we wish, or we can include them.”
Spikey® can treat urine patches with an environmentally safe mix of chemicals already widely used in agriculture. One of these, ORUN, is a mix of an urease inhibitor (nbpt - which inhibits conversion of urea to ammonium) and a growth promotant. Keeping urea in its original form for a vital few extra days, enables it to spread, making a larger urine patch over a greater area with a lower concentration. This allows more nitrate to be taken up by the pasture for growth and less left to leach into waterways.
A new urea spreading sytem was also developed to be used in conjunction with Spikey®. The new technology was originally designed to apply wetted prills in a method known as “OneSystem” that significantly increased the NUE (nitrogen utilisation efficiency) of the pasture. This technology required a new concept in spreader design that precisely delivered low rate fertiliser application in a ‘follow the cows’ basis (applied soon after the cows leave the paddock). It rapidly became apparent that, with this technology, significant savings in urea and other maintenance fertilisers could be made. Using less fertiliser for the same dry matter response resulted in saving on fertiliser.
Combining the two technologies also resulted in time (and fuel) saving for farmers, in addition to promoting increased dry matter production. Geoff says that will have a huge impact on our rivers and lakes - and for the farmers, it means they can continue to be in business without having the issue of nitrate loss hanging over them.
Each unit costs about $65,000. For an average farm of 400 cows, Geoff estimates a cost of $6,000 per year in chemicals, with labour costs ranging from $15,000-$20,000. Research suggests the average dairy farm could make a net profit of $15,000-$20,000 annually from the extra grass produced using the system. But possibly it’s greatest benefit is allowing farmers to continue dairy farming.
Lachlan Mackenzie has been trialling Spikey® on his farm as part of a consortium of five farms (Five Spikey Farms Ltd) which bought the first production unit. Lachlan is also on the board of Pastoral Robotics. He used to apply granulated urea after the cows grazed but now uses Spikey® to treat urine patches and apply prilled urea. Grass growth is calculated to be 5-15% extra a year with the additional cost of running the system around $58/ha.
Pastoral Robotics has had interest from the Irish dairy industry and agricultural research department (Teagasc) as they look to foster grass-fed milk with its potential to earn a premium.
On April 7 this year Pastoral Robotics announced a further development in their technology - DCD equivalence for its new nitrification inhibitor, NitroStop™.
Testing of the key components of the NitroStop™ urine patch treatment mix in rhizosphere (root zone) and lysimeter trials achieved the same level of nitrification inhibition as DCD. Nitrostop is a replacement for ORUN. Geoff Bates says it is “a major breakthrough in the dairy industry’s battle to clean up our water”.
When NitroStop™ is applied through their innovative urine patch detection and treatment machine, Spikey®, it becomes a much needed practical solution to nitrate leaching which, at the same time, increases pasture growth and improves farm productivity.
The withdrawal of the nitrification inhibitor DCD, due to residual detection in milk, left a hole in the dairy industry's available tools to fight nitrate leaching. Pastoral Robotics Limited is now able to fill that hole – using Spikey® and NitroStop™.
The key ingredients of NitroStop™ are already used in agriculture for other applications and are not expected to have any residual issues.
According to Geoff, the next step is to undertake more extensive lysimeter trials to provide evidence of the effectiveness of the treatment, which can be used to convince regional councils of the performance of this promising solution to a problem of national concern.