SOIL TEST RESULTS INTERPRETATION

Hey dear friends,

I have my first batch of (potential) no-till mix ready and sent a sample to the local lab after 4 weeks of cooking. The recipe is - like most of them - inspired by coot and adapted to use what is available to me locally (i'm in the EU).

Here is the breakdown:
Base soil = Peat moss 40% + 20% composted oak bark + 10% EWC/ Biochar mix + 30% pumice
Amendment per cu.ft
- 1/2 cup kelp meal
- 1/2 cup neem cake meal
- 1/2 cup alfalfa pellets
- 1/2 cup chicken shit pellets (4-4-4)
Minerals per cu.ft
- 1 cup mix of basalt and dolomite (I have 25 kg of Cuxin DCM i use for my garden. It's 11% MgO and 32% CaO)
- 1 cup diabase
- 1 cup bentonite
- 1 cup gypsum

I have made enough soil for a full 10 gal container.

My lab doesn't offer testing for potting mix specifically but told me their test for compost is also adapted. The problem is there is no interpretation of the results (I mean yes but for using it as a compost) and as I'm not an soil scientist, it is difficult for me to judge and compare it with tests from the USA/ Canada, with other units and methods probably also...

My feeling is the mix is high in sodium.. Also the Ca and Mg seems to be high and it makes sense as the ph is 6.96. Ca:Mg ratio is 3.5 but my tap water contains a lots of Ca and almost no Mg so it should balance out with waterings.
The C:N ratio of 31:1 is also very high, probably from the composted bark.

I have estimated the CEC and base saturations by converting the FM results from g/L to meq/ 100g:
CEC ~ 40
Ca 62 %
Mg 17%
K 5%
Na 11% (!!)
other bases 5%

Any help for the interpretation of the results is welcome!!
Cheers

ps: TM means dry matter and FM is fresh matter or as received.

Problem with testing a peat based mix is it’s not soil, technically…..

most soil testing labs are geared to mineral soils out of the ground. Not soiless mixes that are made for a container like coots mix.

either way, when I get soil test done it’s not for doing anything besides tracking. And for the topsoil there’s usually an agronomist who can make recommendations based of those results

I’m not sure it’s super helpful in your situation.

Best way to test anew mix, plant something in it.


—also, if I could critique your mix at all I would definitely add more humus material or compost/ castings. Getting to more like 25-30% castings/compost will be beneficial.

Sorry could be more help. Maybe someone else can chime in.

Thanks for your reply mate.

This soil test is not a regular field soil test and as been tested as a compost, which according to the lab is also adapted to potting mix.
Of course it makes everything uncomparable with other testes I see on the web also..

I will plant a seed in this mix tonight, let's how it goes!

juansensor said:

Thanks for your reply mate.

This soil test is not a regular field soil test and as been tested as a compost, which according to the lab is also adapted to potting mix.
Of course it makes everything uncomparable with other testes I see on the web also..

I will plant a seed in this mix tonight, let's how it goes!

Click to expand...

You could always throw a tomato plant in a solo cup worth to see how it goes. I wouldn’t sprout cannabis straight into it. Germinate and sprout in something smaller and transplant once it’s established

edit: some kind of seed starting mix, or peat/perlite mix would work better to start

Had the same idea and I made a test in solo cup with squash. It grow with large leaves well since 2 weeks so I guess everything should be fine.

I'm doing autos so I prefer not to start the seeds somewhere else than the final bag.
Should I make a hole with starting mix and plant the seed in that ?