Plantain Study Holds Potential for Greenhouse Gas Mitigation
Camilla has just finished her PhD project which studied nitrogen compounds and plant metabolites in cow urine and identified those which might minimise nitrous oxide emissions. In particular, the research focused on chemicals contained in plantain, a herb with a fibrous and coarse root system that grows throughout New Zealand.
Indications from the research are that aucubin, a compound found in plantain, may inhibit the release of nitrous oxide from patches of cow urine in paddocks, and may also prevent some nitrogen leaching from the soil and ending up in waterways.
Camilla’s research was conducted under the science leadership and capability building programme of the New Zealand Agricultural Greenhouse Gas Research Centre (NZAGRC), which funds researchers to work with leading experts in New Zealand and prepares them to pursue either post doctoral positions under guidance from NZAGRC science leaders, or enter into industry-based positions.
“The concentrated application of nitrogen in the urine patch is way too much for plants to absorb, so the excess nitrogen can easily be lost as nitrous oxide into the atmosphere or as nitrate into groundwater.
“My research looked at ways to inhibit certain nitrogen transfer pathways, particularly nitrification. We looked at the way grazing livestock’s diet can alter urine composition, and how these changes can affect urine patch nitrogen loss. Varying urine nitrogen composition had no effect on nitrous oxide emissions and some urine nitrogen compounds showed no inhibiting effect on microbes in the soil.
“However we got some encouraging results when we looked at plantain and its active ingredient aucubin.”
The research team collected urine from cows, manually added aucubin to it, and then tested it in paddocks of perennial ryegrass and white clover to get a comparison with the effects of the cow’s usual urine.
“Some trials showed a significant reduction in nitrous oxide emissions, particularly in the first ten days after the cows being released into the paddock, while others were less successful. The project also revealed a second line of research potential – the roots of the plantain may also be excreting aucubin into the soil and inhibiting the leaching of nitrate. Plantain is being increasingly used in farms across New Zealand, as a result of many studies across farm systems, grazing management, plant science and soil science.
Those are areas of research Camilla is furthering in her new role as a post-doctoral fellow in the Faculty of Agriculture and Life Sciences at Lincoln University’s Department of Soil and Physical Sciences.
Originally from Seattle, she moved to Canterbury from the USA at the end of July 2015. She had studied Environmental Sciences with honours in Soil Biogeochemistry at the University of California Berkeley and was encouraged by her thesis supervisor to investigate PhD options in New Zealand. That led to her working with Dr Tim Clough under the NZAGRC’s nitrous oxide mitigation programme, and she has just obtained NZ residency.