Knowing how to calculate the weight of soil in the right way can help you judge the watering and fertiliser requirements for certain plants. It's simple to calculate the weight of the soil. However, because of the variability in soil, it's difficult to know exactly how much a large amount of soil will weigh. The weight of your soil will also vary, depending on how wet it is. Try estimating soil weight when it's at a normal moisture level, not right after a rain.
Spray-paint a square box on the surface of the soil, 1 foot on a side.
Clear all of the vegetation from inside the area you spray-painted.
Remove soil inside the box down to a depth of 1 foot. The volume of soil removed will be equal to 1 cubic foot.
Place all of the soil removed in a pre-weighed bucket.
Weigh the bucket with the soil in it, and subtract the weight of the bucket to get the soil weight.
Multiply the weight of the soil by the volume of soil whose weight you're calculating. For example, if you would like to know the weight of the soil in your 5-foot-by-10-foot garden to a depth of 3 feet, multiply 5 times 10 times 3 times the weight of 1 cubic foot of soil. If your pre-measured soil weighs 24.9kg., for example, the soil in your garden weighs 3742kg. to a depth of 3 feet.