What is the method?
In short: You bury two tea bags, wait three months, retrieve and dry them and measure their weight loss. More details can be found under ‘Method’.
What do I need?
You need a scale that can weigh the tea with two or three decimals precisely. Further, the right tea and something to dig a hole. A ruler can be handy to measure the depth of the hole. See also the method section in the menu bar.
Why can I not dig down tea in my garden/ in a pot?
Your garden likely contains many plants that are not typical of the plant community and the climate that you are living in. Many gardens are also fertilized and have soils added from other regions. As all these factors affect decomposition, burying tea inside your garden will not give values that are representative of the natural soil around you. As we model large scale gradients, based on average conditions, we have to make sure that the measurements are also taken from locations that represent those average conditions. Gardens usually represent very local conditions. However, if your garden is very natural and representative of undisturbed, natural soil, you can bury the tea inside your garden.
Why do you use plastic teabags?
Because we are interested in the tea inside and plastic does not decompose. Remember that after the experiment you do not throw your tea bags with the organic material, as the tea bags are plastic.
What does air dried mean?
Air dried means dried under ambient conditions to the air, without applying any special drying treatment, e.g. by using an oven. The bags are air dry when they feel and look dry. Tea comes air dry from the package. Also when you have placed them in the sun for a few days, you can consider your tea to be air dried.
My tea bag has a hole, can I still submit the data?
No, because tea can be lost from the hole. We can therefore not be 100% sure that the measured weight loss was due to decomposition.
Roots grew into my bag, what should I do?
Remove all roots carefully from the bag. Sometimes it is necessary to open the bag. Do this very carefully so that you do not lose any tea or mix tea with the soil outside on the bag. The best is than to take another container (e.g. a paper cupcake form) and dry the tea in there after picking out the roots. Weigh the tea together with the (now) empty bag, and subtract the weight of the container. This is because the data submission form asks you for the total amount of tea and bag and rope (without the label).
Soil came into my bag, what should I do?
If you are a researcher, you can use the Los On Ignition method to determine the weight of the tea. If you are a citizen scientist, remove the soil as good as you can, and write a note about this in the comments section when you submit your data.
I lost one of the tea bags.
That is a pity, we cannot use the data. We need both tea types for the calculation. Thank you for your effort none the less!
I lost the rope and the label.
You can still submit the data, as long as you know which bag is which type of tea. This can also be detected visually. The green tea usually dries to a solid grain whereas Rooibos is looser and course in structure. Usually the rooibos teabag contains more material compared to the green tea that can be nearly empty. Either weigh the bag that lost its label with the rope of another bag or add 0.03 or 0.029 to the weight, depending on the precision of the scale that you used.
Why should I remove the label before I determine the endweight of the bags?
The label consists of paper and plastic. The paper will also decay during the incubation period. This will cause error in the weight loss of the tea. The other parts of the bag are from plastic and we therefore assume that they do not lose any weight. At the start of the experiment the label (and the rest of the bag) has a very constant weight. You can therefore calculate the start weight of the tea inside the bag by subtracting the standard weight of the bag, rope and label, and the end weight of the tea by subtracting bag weight and rope.
I did not write down the date at which I buried the tea.
Take your best guess, two or three days error does not give us nightmares.
I cannot find my tea bags because my experimental site got destroyed/mown.
That is not nice. Try to find the tea bags and see if they are untouched. If they are above the ground you cannot submit the data. To prevent this, you can make a map specifying distances to things or objects that cannot move. E.g. 2 meter from the tree on the left and 2 meter from the pathway on the right. Placing a stick next to the tea bag and attaching the rope to the stick with a clip may also help to find back the tea bags, but it may also attract people to come and take a look and trample the place.
How can I calculate k and S?
TBI parameters can be calculated using the sheet on the datasumbission page for more than one datapoint.
If you have more replicates per plot/replicate unit, there are two options. One: you can calculate your TBI parameters pairwise, as we suggest in our calculation sheet. However, it might be that the variation in habitat conditions within your plot occurs at such a small scale that the green and rooibos are not really pairs. In other words, there is the same degree of variation between the pairs as within the pair. If this is the case, you can calculate S using the green teas, average it and use this average S to calculate k, for your separate Rooibos bags.
Should I determine the weight of an empty bag?
Yes this is a very good idea!
Should I determine moisture content of the tea?
Yes this is a very good idea, also determine loss by handling when you travel to the field site. However, the latter one is often negligible, especially when you use the box in which it came as travel vessel.
On the project
How many countries and teabags have been buried so far?
The number of locations and tea bags is growing, please check the list of acknowledgements and the map to see where tea is, and has been buried, respectively. In 2016, people promised us to bury tea on over 1500 locations.
When did the project start and how long will it run?
The project started in 2010 and will last at least until 2020.
What is the goal? And Why are you doing it?
We want to create a global map of decomposition, with which we can test our current ideas about the relation between climate and decomposition. Until now, such efforts have been frustrated by lack of comparable data.
We also think that it is important to increase awareness about soil processes and climate change. Even when a citizen scientist did not manage to complete the experiment, we still consider it successful as he or she will still have learned something from it.
What do teabags tell about climate change?
With the tea bags we can measure how much and how fast plant material decomposes. Decomposition is an important step in the carbon cycle which is strongly affecting climate (change). When plant material decomposes the soil will release CO2 and the speed and degree of decomposition will determine how much CO2 is released to the air. As CO2 is a greenhouse gas, the amount of CO2. is important for climate change.
Why is it important to improve climate models?
Because these climate models tell us how we affect the earth and whether we need to take more action to prevent large changes that are harmful for the earth. Until now, many climate models depend on estimated decomposition rates. We want to supply those methods with actual measured data. This was not possible before because methods to measure decomposition required a lot of effort.
Do you have to use this specific tea of Lipton?
Yes, otherwise we cannot compare the results. Other tea types will decay in different ways.
Are you sponsored by Lipton?
No we are not, but we would have nothing against it. We received funding from the Swedish Vetenskapsrådet and the institutes at which we work allow us to spend time on this project, which we are grateful for.