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Using tea bags to measure soil carbon storage

What can we tell about climate change by burying the humble tea bag? You'll be surprised . . .

Different soils have different decomposition rates depending on their composition and chemistry. This rate can be influenced by the vegetation growing in the soil, for example, grasses vs mature trees.

The faster the decomposition rate, the less plant material (carbon) will be stored within the soil. 

We want to find out if the soil under different farm habitat types is able to store different amounts of carbon, so we started burying tea bags!

The Tea Time 4 Science method is a set of protocols that was developed in Europe back in 2010, and have now been used all around the world. It's a cheap and easy way to look at the carbon being stored in soil on and see how this might be affecting climate change. 

We buy specific types of tea bags, weigh them, and then bury them for three months. The soil will decompose the tea inside the bag, but not the bag itself. So when we exhume the bags and weigh them again, we can calculate how much tea has been decomposed.

 

If we do this in pasture, native forest, native scrub and pine forest (these are often found on sheep and beef farms) then we can compare the soil decomposition rates and, by proxy, the relative carbon being stored in the soil of each habitat type.

Our second lot of tea bags are in the ground right now, so we'll let you know when we've retrieved and weighed them, then analysed the results!