If you want a complete soil composition test, I would suggest you collect some soil from around your garden…or a particular area, if you are just interested in the soil composition of that part of your yard…and send off your sample to a reputable laboratory. Depending on how much information you require from your soil sample, the lab will do the appropriate tests. For a price, of course.
But if you are a science geek…or are only concerned with some rough results on your soil sample…by all means do this simple test at home. It will certainly provide working knowledge of what soil type you are dealing with in your garden.
Soil Test Recipe
1 quart (1L) jar with tight-fitting lid
1 c (250ml) soil (air dried)
1 tsp (5ml) plain, non-sudsing detergent (such as Murphy’s soap)
water (enough to fill jar two-thirds full)
1 black marking pen
ruler or measuring tape
clock or watch
Combine ingredients in jar, except black marker. Screw on lid and shake jar vigorously for 2 minutes. Set jar on table.
Let sit for 1 minute. Mark the level that has settled to the bottom of the jar with the black marker. This is sand.
Let sit for another 2 hours without disturbing. Mark this level with the black marker. This is the silt level.
Let sit for 2 days. Mark this level with the black marker. This is the clay level.
Measure the total height of the settled soil and the individual levels marked on the side of the jar to calculate the particle make-up of your soil.
Example: height of settled soil = 3” (7.6cm)
sand level = 7/8” (2.2cm)
silt level = 1 1/8” (2.9cm)
clay level = 1” (2.5cm)
Soil composition = 28.9 % sand, 38.2 % silt and 32.9 % clay
Optimum is: 40% sand, 40% silt and 20% clay