Landcare Research - Manaaki Whenua

Landcare-Research -Manaaki Whenua

Digging deep

What are they doing down there?

Nitrogen leaching from fertiliser applied to grassland can contribute to greenhouse gas emissions and contaminate groundwater with nitrates. Finding ways to reduce or prevent this will help farmers protect our environment. This year, in an example of high-impact teamwork, Manaaki Whenua – Landcare Research scientists and technicians took a look at nitrogen cycling by microbes deep in the ground.

They collected core samples of undisturbed soil at previously unstudied depths. Since standard equipment wasn’t cut out for the job, Graeme Rogers forged a relationship with the McMillan Drilling group, who designed a custom-made drilling head to plunge PVC pipes to a depth of 1.7 metres into the extremely stony soils of the Ashley Dene Research and Development Station.

The samples were sifted by depth and sent to the lab, where Carina Davis and her crew sorted root, soil and stone samples for DNA sequencing of the microbes.

The team hopes to identify the activities of the specific microbes regulating the nitrogen cycle at depth, and to understand how different deep-rooted plants promote these activities. They suspect the fungi and bacteria are doing all the hard work and are far more active at depth than previously thought.

If confirmed, this could help with developing options for farmers to improve land management and reduce nitrogen losses.