Second report from the TMAF Flux Towers monitoring carbon

Half a year into the carbon monitoring in sugar beet with the TMAF Flux Towers at Morley, lead researcher Dr Georgina Barrett from BBRO shares the latest news from the trial that is attracting lots of interest.

The flux towers have now been in place for six months. Since their arrival (reported in March 2023), conditions have been good for sugar beet growth with sufficient rainfall and few excessively hot days, the complete opposite to optimal conditions for the current cereal harvest!

The towers have been operating well, with only a small fault so far. This was a leak on the regulator which contains the zeroing gas. This is used by the system to calibrate the gas IRGA to ensure that the CO₂ measurements are correct. Once detected, this was quickly rectified, and the data from the towers is looking good.

Another challenge we were aware of from the start was growing sugar beet immediately under the flux tower. It was decided that beet would only be planted directly under the radiometer arm so that the sensors could measure the crop which is then used in the flux calculations. This decision was made because managing the crop growing immediately under the flux tower would be challenging as it is not accessible by machinery, so would need to be hand sown and sprayed to control weeds, pests and diseases.

The small patches of beet grown under the flux tower arms has not grown as well as the commercial crop, and this has led to the UK Centre for Ecology and Hydrology (who operate the flux towers) to order a tripod system that means the crop monitoring sensors can be placed in the commercial crop, away from the main flux tower mast (Fig.1). 

What the data tells us so far

The data collected has shown a contrast between the two fields, mainly driven by an infestation of ryegrass in one field (Fig.2). Early on, this appears to have resulted in slightly more carbon being taken up compared to the field without the ryegrass as there was a greater amount of biomass being produced.

However, the ryegrass has competed with the beet which now has a lower biomass than the field without the ryegrass and resulted in this field having now taken up more carbon. This highlights an important message that good crop husbandry and growth of the crop will increase the amount of carbon taken up by the crop.

Although this carbon will be released in the short term, through harvest and processing of the beet, the carbon balance of the crop will be better as more beet will have been produced for the same amount of carbon input through inputs such as fertilizer, fuel and crop protection sprays.

Visitors to the tower sites

The flux tower sites have been visited by lots of groups, with farmers across the UK and from the wider agricultural industry curious to see what we are doing at Morley and why. This has been a great opportunity to engage in discussions and debates over the best approaches to reach net zero and the challenges and opportunities arising.  

It’s been fascinating following the carbon dynamics of the crop so far. The next phase will be interesting as we look at emissions from harvest and how management practices drive emissions into the following cereal crop.

Find out more about TMAF’s Carbon Monitoring in Sugar Beet.