Soils 101: How to know your type of soil, and what this means for you

Here at Grow-Mate we’re all about soils. And not only because we sell organic fertilisers to build up your soil (which we do, and we’re darn good at it), but because we understand that any successful gardener begins by breathing life into his soil before trying to get any beautiful chili peppers or tomatoes to pop.

And yet, even before building up your soil with organic plant food it’s important to have a clear perspective of what is soil. To remain in the basics, we can simply say that soil is the mixture of several things: gasses (like CO2 or oxygen), liquids (water), minerals and organic matter. Of these, the liquids and organic matter are normally what a gardener introduces when building up the soil, by irrigation and fertilization. The issue with minerals, though, is more complex:

Triangular chart depicting the different compositions of soils.

Yeah, way more complex.

Although there are other ways to classify them (mostly of interest to scientists), the chart above basically describes the types of soils according to how much they contain of three things: sand, clay and silt. In order to know the type of soil that you have, you need to take a sample of it to a laboratory, where they will perform a particle size analysis, or PSA. They will measure the sizes of the particles in your soil, and determine the percentage of sand, slit, and clay content based on what percentage of all the particles has the size of sand; what percentage has the size of slit; what percentage has the size of clay and so on. Ultimately, you will receive an estimate in the form of “40% sand, 40% silt, and 20% clay”, which will allow you to go to this pyramid and do the following:

Particular case of a type of soil, within the triangular chart.

Follow the lines that begin in each percentage of either sand, silt or clay, until they cross with each other. The point where all intersect shows under which category your type of soil falls.

Now, what does this mean for you? If you have this soil composition, you’re a lucky fellow ― that’s the ideal one for growing crops! Everything under the label of ‘loam’ is cultivable to some degree, however, so don’t give up if yours is silt loam or clay loam: it just means that you’ll have a bit heavier soil in either case than with sandy loam, which will be looser, leaving more water flow deep into the earth. On top of this, soil can always be improved by adding organic matter, whatever type it originally is (it’s just that if your soil is pure clay it will be much, much harder to do that!). In addition, be sure to add organic fertilisers over time as well, to prevent the nutrient depletion which, according to a FAO report of 2015, is a major threat to all cultivated lands around the world. There are many advantages to organic fertilisers (especially ours, which you can check here), but that’s a topic for our next entry in Soils 101, the series in which we explore soils from the ground up. Happy growing!

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