AgResearch scientists have created a new device to help farmers tackle the problem of nitrogen loss from cattle urine.
This device, an acoustic urine sensor, attaches to the rear leg of dairy cattle to enable recording and identification of distinct sound patterns in “urination events”, including timing and volume.
Data from the recordings is analysed using technologies that include machine learning.
Dairy cows typically urinate 10-12 times per day with an average urination volume of 2 litres per event and an average equivalent urinary N application rate estimated to be 600kg of N per hectare.
N loss from cattle affects water quality and leads to emissions of nitrous oxide, a potent greenhouse gas.
AgResearch senior scientist Dr Brendon Welten said their research showed the N load of an individual urination event is closely connected with daily urination frequency, the time of day and the volume of the urination event.
“This means that urination frequency and volume per event directly affects the amount of N deposited in urine patches on the pasture.
“Therefore, cows that urinate more frequently per day coupled with a lower volume per urination event tend to excrete lower amounts of N per urination event and so represent a lower risk to the environment.”
This knowledge has led to AgResearch developing the concept of an environmental N herd test to identify and manage cows based on urinary-N loss potential.
The concept is similar to routine herd testing for milk quality and production, with a service provider deploying the urine sensor technology on a dairy farm to provide an accurate estimate of an individual cow’s urination frequency and volume per event.
This informs the urinary N loss potential of individual cows in the dairy herd.
“Once farmers have this farm-specific urinary N loss information of their dairy herd, this could be used in a decision support tool like Overseer to allow potential immediate benefits in reducing farm N loss relative to using a default model value.
“Furthermore, farmers can then use it to make farm management decisions, such as breeding and culling, to move their dairy herd towards lower N loss potential and it thereby provides the opportunity to achieve sustained reductions (year on year) in farm N leaching loss.”
The research behind the sensor development was recognised when AgResearch’s Cattle Urine Sensor team won the Science and Technology Award at the 2023 Kudos Awards in Hamilton.
“It’s fantastic to have that recognition given over five years of development,” Welten said.
“The benefits of these sensors are that they are lightweight, simple to use and low-cost. Their use can be easily scaled up and requires no capital investment in farm infrastructure, with minimal effect on daily farm management practices.
“Our current research is assessing farm-level benefits of this concept on farm N loss using case-study dairy farms linked with modelling funded by the Ministry for Primary Industries.
“We are looking forward to the potential large-scale adoption of this concept in the future by New Zealand dairy farmers as a new tool to mitigate farm N loss.”
