Nice project
. Now you only have to do 5000 more repetitions using different components in various ratios to find "the perfect" one..... I've never used Seramis. What is it designed for?
The real kicker is how much each tree takes in in a given season and how to compromise on a mix that works all year where you live. Where I study, we go for faster draining mixes; there are also apprentices here who check water sometimes 5 times a day and water any given tree 1-3x a day. It must be nice having "watering drones" as Mike Hagedorn calls them.
Those tests are a very nice start. Different containers have different zones of saturation and some pots (especially old Chinese pots and converted suibans) tend to keep more water in the bottom.
I look forward to hearing more of your results. It would be great if you combined different components and see how it affects the results.
Seramis is a German fired clay product designed for plants -
http://www.seramis.com/. Its $17 for 7.5L. There are some videos posted on their site of a similar experiment to what I undertook here. It's where I got the idea for doing this. And to do 5000 more tests - yikes - I'd need my own set of watering drones! I just have 4 kids and a wife who all think I'm a bit off and want no part of my beakers and ziplock baggies filled with gravel.
In the summer here our climate is pretty tropical - it gets to one thousandty degrees outside (according to my daughter). And the only creatures that seem to like it are the mosquitoes. During that time, water retention in the soil is a concern for us working folk whose employers frown on their employees taking off every few hours to water our trees. In the heat of the summer I water before I go to work, have a sprinkler that comes on at mid-day, and water again in the evening - it's usually pretty dry by then. The good news is that summer only lasts 14 months per year.
Also, its interesting that you mention pots. I''ve started to look at water retention as a funtion of the pot shape. I haven't finished that yet, but directionally it appears that an equivalent volume of soil has a higher field capacity in a shallow pot than it does in a deeper pot. It also appears that adding a drainage layer has the same effect (it makes the mix more water retentive). I'll post more on that later. Not sure why old Chinese pots in particular would make a particular difference - if you send me a few, I'd be happy to test them for you!
I have tested some mixes as well - I'll post those results later.
Scott