Soil chemistry testing with LaMotte Soil Test Kit!
I have tested my soil nutrients and composition before. I made some lame attempt to address deficiencies, adding compostfor depleted nitrogen and fireplace ashes to raise the pH. Results were – meh. THIS year, I vowed, would be different. I would have the patience to get to the bottom of my soil conditions and scientifically address them!
Out comes the Lamotte Soil Test Kit. I love this thing. It reminds me of the chemistry kits I envied but never had as a kid.
Here is the deal:
1. Take soil sample from a few inches below the surface. Integrating from a few spots throughout the bed is a good idea (whatever).
2. Spread out the soil to dry (I used squares of tin foil so I could save the sample for later), removing rocks and plant debris. Crush clump to speed drying.
3. When soil is dry, crush it through a fine seive. I used my fine metal kitchen colander.
4. I also weighed my samples plus the debris that didn’t make it through the seive to calculate % coarseness. Cause I’m a geek.
5. Perform soil tests. Kit includes testing for pH, N, P, K.
6. Additionally geek out by performing a soil composition test.
Here are my results:
All of my untended beds (by this I mean completely ignored all winter with no cover crop or protection) had the same results: pH 7-7.5, Trace N, high P, high K. I expected low pH, so maybe this means last year’s fireplace ash application more than did its job. That might also explain the P and K.
The low N seemed extreme and made me wonder if the test was working right. Until I measured my asparagus bed which had – shocking – different results: pH 6.0, High N, moderate P, high K. I had recently top-dressed this bed with 1″ compost, so even though I dug down under that for my soil sample, it would seem compost makes a difference!
I will apply 1# of fireplace ashes/sqyd of asparagus bed to bump the pH closer to 7, but they like it a bit on the acid side, so I’m not too worried.
What do do about a soil that needs a ton of N, but little else? I have decided on feather meal. It contains about 15% N, works at cool temperatures, and releases N for up to 6 months. The LaMott guide suggests 10# N/2000 sqft for ‘Low’ N soil result. Other places I read twice that. So I’m going for 0.01#/sqft. For my 275 sqft of veggie beds, I will need 2.75# of N. At 15% N, that means 18# of feather meal. My local(ish) source sells feather meal in 20# bags – Done!
Gorgeous, but can you see how there are two colours there? The purplish-blue one at the surface is the right colour (7.5). Below that, the suspended fines are clouding the solution. When I let this settle for several hours, the water column was all 7.5.
Again – beautiful! But a bit on the high side…
This was the result for most of my beds – making me question whether the test was working properly. Until I saw the asparagus result.
Again, see how the fines interfere with colour interpretation? The blue-green colour (6.60) at the top is correct.
Aha! There be nitrogen! This was the recently-compost-ammended asparagus bed.
Sustainable Scientist 