CRAN
ChemiResistive sensors for effective Agricultural N management and nitrous oxide mitigation
Nitrous oxide is an important greenhouse gas and a stratospheric ozone depleting substance. It is released from soils with excess nitrogen, so it also acts as a marker for nitrogen waste – for example, when too much fertiliser is added to agricultural fields. The Swiss Nutrient Reduction Initiative (Absenkpfad Nährstöffe) aims to reduce losses of nitrogen (and phosphorus) from agricultural systems by 20% by 2030. Reducing N2O emissions leads to an overall reduction in N losses from agriculture. However, we need to accurately measure N2O under different management conditions to understand how different policies affect nitrogen budgets.
Sustainable development of Switzerland’s agricultural sector plays a key role in environmental protection. Switzerland’s agricultural sector produces food and preserves the landscape, but only makes a small contribution to the economy as a whole. Image credits: © Swiss-image.ch / Gerry Nitsch.
Measuring N2O is difficult. N2O emissions vary a lot with time, depending on environmental factors like temperature and rainfall, and management factors like planting, fertilisation, and harvest. We can capture this variability by measuring in one position frequently over long periods of time. N2O emissions also vary in space, due to small changes in soils and microclimate. for example, the lowest part of an agricultural field is usually the wettest, and this causes higher N2O emissions. To capture this variability, we need to measure in a lot of locations across a site. Moving our equipment takes a lot of manpower and also disturbs the soils and plants, so we need low-cost N2O sensors that can be installed at many locations across a site.
In the CRAN project, we are working to develop low-cost sensors to measure N2O in soils. These sensors use chemiresistor technology: A chemiresistor is a material that changes its electrical resistance in response to changes in the nearby chemical environment. We will develop a chemiresistor material that responds to N2O and converts the concentration of N2O in the soil pore space into an electrical signal. We will test the sensor at an experimental agricutural site, and develop data processing and modelling packages to interpret the data easily and efficiently.
Schematic of the CRAN project approach and division into four work packages.
We hope that eventually this technology will allow farmers to directly measure N2O emissions in their fields, and adapt their fertilisation and management strategies to minimise N2O emissions and reduce N losses.
Project scientists
Laboratory of Inorganic Chemistry, ETHZ: Prof. Dr. Máté Bezdek (Co-PI), Dr. Simon Rickert (Postdoc)
Climate and Environmental Science, University of Bern: Prof. Dr. Eliza Harris (Co-PI)
Grassland science, ETHZ: Prof. Dr. Nina Buchmann
This project is funded from 2024 – 2026 by ETHZ’s World Food System Centre and Fenaco through the Smart Sustainable Farming Research Program.