Measuring soil greenhouse gas emissions in WorldVeg field trials

Since March 2024, new game-changing equipment – LI-COR Smart Chamber – has been allowing WorldVeg scientists to very accurately monitor the effects of different soil amendments and agronomic practices on the emissions of soil greenhouse gases (carbon dioxide, methane and nitrous oxide). This is of huge importance for identifying ways by which agriculture can be more sustainable, and change from a net emitter to a climate change mitigation solution. WorldVeg for the first time is now able to make such assessments, and that will accelerate research efforts towards ‘net zero’ strategies in agricultural systems, which is becoming a key priority for Taiwan and many other countries.

Lukas Pawera, WorldVeg Agroecologist, explains. “The Smart Chamber is quite a unique piece of equipment. As you can see, it is very portable, comprising of a survey chamber connected with a gas analyzer in this ‘suitcase’ that analyses real-time gas concentration and fluxes. There is also an integrated soil sensor that measures soil EC, moisture and temperature, which are key parameters influencing soil greenhouse gas emissions. At spots randomly selected across the trial plots, we place plastic collars into the soil where we take measurements every 7-10 days. You can operate it through software installed on your computer or smartphone. The Smart Chamber can be carried around by a single person, and measure multiple experimental plots producing invaluable results.” Lukas further adds that “But it is still hard work, as our students, supported by research assistant Cheng-Wei Chen, need to measure many plots and this takes around 4-5 hours to do them all. But this data from real field conditions is extremely valuable”.

The equipment is currently being used in two different research trials at WorldVeg headquarters in Taiwan. In one trial, PhD student Lokeshwar Kesamreddy from Tamil Nadu Agricultural University is looking at the effects of biochar when combined with mineral and organic fertilizers on soil carbon, GHG emissions and okra production. The aim is to identify suitable rates of biochar (from rice husk) that have positive effects under both conventional and organic nutrient management approaches. The second trial is being implemented by MSc student Ruth Obara from Egerton University in Kenya. Ruth is looking at the impacts of interplanting okra with nitrogen-fixing mungbean in different planting patterns compared to monocultures, and under three different doses of nitrogen, to see whether a mungbean intercrop could partially substitute mineral fertilization, and how this affects system productivity, soil properties and greenhouse gas emissions. 

Ruth shares her initial observations of using this equipment in the field. “My experience with the LI-COR Smart Chamber has been very positive. The equipment has proven to be both efficient and effective, as preliminary results are quite variable across different treatments and replicates. The 100% recommended nitrogen dosage rate in monoculture shows the highest emissions so far, while the 0% and 50% treatments both show lower emissions. Additionally, higher emissions are seen in row intercropping compared to mixed intercropping, but we need more data to see the patterns more clearly.”

According to Lokeshwar, the equipment gives accurate and reliable data. “Preliminary observations in my experiment show that the control without any fertilizer and biochar shows less greenhouse gas emissions, and for the rest of the treatments comprising biochar in combination with organic and mineral fertilizers, emissions are differing. But I will keep collecting more data that is required to conclude which treatments show good yield while minimizing trade-offs for the climate.”

Lokeshawar and Ruth are visiting students, part of a group of 11 currently at headquarters who received Golden Jubilee scholarships funded by the government of Taiwan during the WorldVeg 50th anniversary year in 2023. The new equipment was made available through the framework of the Open Science Center agenda that is also generously funded by the government of Taiwan.