By Rob Smith
Photography by Victoria Rutherford

Lincoln University researchers working alongside Ravensdown have discovered that a naturally occurring microbe could help substantially reduce greenhouse gas emissions from agriculture and the loss of nitrogen to waterways.

Director of the Lincoln University Seed Research Centre Professor John Hampton and Biotechnologist Dr Hossein Alizadeh (Hoss), are undertaking the research and describe their findings as a ‘game changer.’

Microbes are present in all soils. John and Hoss have discovered that isolating certain strains, multiplying them, then adding them back into pastural soil to boost the naturally occurring level of specific microbial activity has potentially beneficial effects, both for production and for the environment.

“Our research has found that increasing the incidence of specific naturally occurring beneficial microbes enhances plant nitrogen use efficiency,” John says.

Microbial activity is associated with the conversion of urea into ammonium, he explains. Further microbial activity converts ammonium to nitrite and nitrate that can end up causing environmental damage via nitrous oxide gas emissions or nitrate leaching.

“We know that certain microbes interact with other soil microbes to alter the pace of this conversion. In this instance, one set of microbes is detrimental to pasture. However, another set, which is our beneficial, reduces the population of the first set of microbes, therefore reducing the pace of urea’s conversion to ammonium.”

They have measured the reduction in urea’s conversion to ammonium. “Following application of these beneficial microbes to soil, the reduction of the pace at which the applied urea breaks down to ammonium enables the plant to take up nitrogen for a longer period,” he says. “Pasture with added beneficial microbes, and therefore more available ammonium, produces more dry matter more quickly than pasture without.”

As well as enhancing pasture growth, this more efficient use of applied nitrogen (N) reduces its loss through leaching and emissions.

In agriculture, N is commonly lost as nitrate leaching through the soil profile, or as nitrous oxide emitted from soil, especially via urine patches. Nitrate leaching is potentially detrimental to waterways, and nitrous oxide is a potent greenhouse gas.

“Being able to easily and naturally reduce and mitigate these losses from the nitrogen cycle is excellent news for farmers, and a game changing win-win from both an environmental and a productivity perspective,” John says.

John and Hoss started their research in 2013, aiming to test the hypothesis that the beneficial microbes they had isolated could reduce nitrogen losses after urea or urine application.

“We isolated these microbes from pasture soils around New Zealand and conducted extensive screening experiments to identify the best isolates of our beneficial microbes,” says Hoss.

“We have an extensive collection of different isolates, some of which have no impact on reducing nitrogen losses. The ones we are now using were the ones that came out on top after our screening work for reduction.”

Four years of results from field trials at sites around New Zealand have shown a range in the beneficial microbes’ effectiveness.

“Responses vary with location, climate and soil type. We have recorded increases in pasture dry matter production of 15 to 21 %; a reduction in nitrous oxide emissions of 30 to 42 %; a reduction in ammonia volatilisation of 18 to 40 %, and a reduction in soil nitrate content of 17 to 27 %,” he says.

John and Hoss's research is part of N-Vision NZ, a major research programme co-funded by Ravensdown. N-Vision NZ includes two other research projects that aim to reduce the environmental impact of New Zealand’s grazed pasture systems: one that will develop an accurate gauge of the nitrogen already in the soil, therefore enabling farmers to apply more precise quantities of nitrogen fertiliser for optimum plant growth; and another that will research nitrification inhibitors, which have the potential to significantly lower nitrous oxide emissions and nitrogen leaching from grazed pasture systems.

N-Vision NZ is a $22 million seven-year programme with $7.3 million from the Government’s Sustainable Food and Fibres Future (SFFF) initiative. Ravensdown is contributing $11 million in cash, plus in-kind funding. Lincoln University and Plant & Food Research are N-Vision NZ research partners.

Ravensdown Scientific Officer Dr Will Talbot is working alongside John and Hoss, with a view to commercialising the results of their research, therefore assisting farmers to increase productivity while reducing environmental impact. Will says farmers and the environment should be able to directly benefit from the research in around four years.

“Further tests and development are necessary before we have a product that can be used on-farm.

“Our ultimate intention is to enable farmers to apply the beneficial microbes to soil as either a prill for existing pasture, or a seed coating for new pasture.

“To ensure that is feasible, more field trials are necessary to continue validation of the responses to the use of these microbes. Before commercialisation we also need to investigate product formulation and options for hill country application,” Will says.