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Jar of water test (approximate method)

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Place one or two cups of soil in a clear glass jar that holds about 1 litre and add water
Photo: liz west (Muffet)

Place one or two cups of soil in a clear glass jar that holds about 1 litre and add water almost to the brim. Shake the mixture vigorously for a few minutes, then let it stand for at least 24 hours, because the clay may take several days to settle (it will settle more quickly if you add 2 tsp table salt).

The mixture will gradually form layers, with sand on the bottom of the jar, silt in the middle and clay on top. Organic matter will float to the surface. You can calculate the percentage of each element according to the depth of each layer.

% sand: (depth of the sand layer X 100) ÷ total depth of the soil in the jar

% silt: (depth of the silt layer X 100) ÷ total depth of the soil in the jar

% clay: (depth of the clay layer X 100) ÷ total depth of the soil in the jar

 Jar of water test

Example:
The following jar contains about 73% sand, 20% silt and 7% clay. The soil has a sandy texture.

% sand = (5.5 cm X 100) ÷ 7.5 cm = 73%

% silt = (1.5 cm X 100) ÷ 7.5 cm = 20%

% clay = (0.5 cm X 100) ÷ 7.5 cm = 7%

Then you can use the following table to classify your soil:

Soil texture % sand % silt % clay
Sandy soil 70 or more 0 to 30 0 to 15
Silty soil 0 to 20 80 or more 0 to 15
Clay soil 0 to 45 0 to 40 25 or more
Loam 40 to 60 30 to 50 15 to 25

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