Local Soil - Gathering & Determining Reported Composition

 I get a special joy out of making things from seemingly nothing and at the lowest possible cost, so while it's a risk I'll be gathering most of my soil components as opposed to buying them. But this brings some fun into it! 

I checked soil composition in local areas I am free to dig up using the USDA soil composition website. It's a bit difficult to figure out, but I managed by playing around with it. First you'll need to determine your area of interest. 

USDA website 

AOI selection tools

Map out your area using the AOI tool that works best for you. You may get an error message, I wouldn't worry too much about it. I zoomed pretty far in on mine, so this is a sample of a different area rather than publish my dad's location 😉 Once you click on soil map, it should look something like this:

Soil Map data page

Now this is one that's quite complicated, isn't it? How do you know the composition of AkA (Alvada loam) vs AmA (alvada silty clay loam) and so on? This is where it gets fun! Under soil data explorer, they have a report that shows all the data you need underneath the map. I clicked "printable version" in the top right section, which opens up the data sheet in a new tab. You can use this to compare general compositions of the local soil areas and determine the best areas from which to farm your soil - and the best depths as well! The first page explains particle size of different soil types, which 

Particle Size and Coarse Fragments Report

One of the soil types in my local region is AmC2 (Amanda silt loam). The soil has different compositions depending on the depth at which it is measured. At 0" (surface) to 8", the soil averages 27% san, , 54% silt, and 12%-27% clay. (l is low value, rv I was unable to determine but may be recorded value, and h is high value) 

For this project, I determined OcB (Ockley silt loam) to be the best region as the soil at surface is 5-17% sand, 61-80% silt, and 11-22% clay. I may separate some of the clay out to have a lower clay content especially if I gather a sample with a higher clay content. If I were buying standard cheap topsoil, I would mix in 5-10% clay for the iron content and so the soil "sticks together". I also do not want a high sand content, as it does not have much in the way of nutrients for my plants and the density of sand can cause anaerobic pockets, which is fatal to plants. 

To gather is simple enough - just dig a bit more soil than you need out so that you can filter it as needed, taking care as best able to reduce organic materials like plant roots and mulch. Here's a handy calculator to estimate how much substrate you will need for your tank size. I have a 20 gallon tank (calculate tank size here if needed) that is 24*12 inches, so I need an end volume of 4.75L (1.25gal) dirt mixture. 

Up next: I'll be determining composition of the soil using the jar experiment method. If I need to, I'll use this method to separate out some of the clay After composition is determined and if needed, the soil is separated to create a better ratio, I'll use this method of separating clay from soil. I'll be mineralizing my soil!