In my never ending quest to learn more, I ventured into Michigan State University’s Plant and Soil Sciences building. There I found a laboratory that tests the nutrient concentration of my soil. For only $11 you can test the Macro nutrients, N-P-K. However, for $25 you can get a test for N, P, K, Ca, Mg, Na, S, Fe, Zn, Mn, Cu, B and Al. I immediately decided to test my SS and a few other composts.
This process tests the total amount of nutrients, not the readily available nutrients present. For example Nitrogen is usually absorbed in the form, NO3, but can exist in other forms such as NH3 or NH4 until it’s decomposed by bacteria into something the plant can use. Most numbers are in % of total soil, others are in ppm.
My previous SS recipe follows Sub’s very closely. I use Roots Organic as my base with the addition of 4 lbs of Kelp Meal. I found it has a Ca and Mg deficiency which was easily corrected by adding some powdered dolomite before a watering. I didn't notice any other deficiency problems with my Agent Orange run. Slight fading in last 2 weeks but I like it. Used half SS half Roots Organic.
The cow, poultry and worm composts are from Morgan Composting, a local Michigan business who makes some great cow compost called Dairy Doo. The last compost is from another local Michigan business called Hammond Farms, who makes a plant based compost.
SS = 1.6 - 0.5 - 0.2
Cow Compost = 1.7 - 0.6 - 1.8
Poultry Compost = 5.2 - 2.0 - 2.8
Worm Castings = 3.2 - 0.6 - 3.0
Plant Compost = 0.9 - 0.1 - 0.4
Here are the original reports.
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