Dr Selai Letica explains some of the causes of nitrous oxide emissions in agricultural soils and why it is important to limit them.
Points of interest:
- Nitrous oxide (N2O) occurs naturally in the environment, but human activities increase its concentration in the atmosphere.
- One unit of N2O is equivalent to 310 units of CO2, making nitrous oxide a more potent greenhouse gas than CO2.
DR SELAI LETICA
Primarily, my research is about finding out how we can reduce nitrous oxide emissions through the use of nitrification inhibitors. My research is also concerned with trying to understand the causes of nitrous oxide emissions from agricultural soils. So that’s looking at the relationship between nitrous oxide emissions and things like soil moisture conditions, nitrogen soil levels as well, and a bunch of soil physical conditions as well – the level of compaction under dairy cows or dry stock like sheep and beef. Also there’s a spatial component, so understanding where in the paddock nitrous oxide emissions are most likely to come from.
Nitrous oxide is a really potent greenhouse gas. If you took say 1 kg of carbon dioxide and 1 kg of nitrous oxide, that 1 kg of nitrous oxide has nigh on 300 times the global warming potential than that same block of carbon dioxide has. So it’s produced in smaller amounts for sure, but what is produced has quite a potential to affect global warming.
In agriculture, nitrous oxide emissions generally occur in a New Zealand setting from the paddocks. That’s because, when stock are grazing on paddocks, where they deposit their urine and dung, they create massive concentrations of nitrogen in the form of urea on the paddock surface. Now, there’s more nitrogen in that urine patch than the plants are able to take up, absorb and use to grow, so that excess nitrogen becomes available for the nitrogen cycle to process that urea form of nitrogen into highly mobile forms like nitrate or can be lost through the process of denitrification to nitrous oxide emissions.
Dr Selai Letica, AgResearch, Invermay