Easy Soil Wash Test for Gardens

In an ideal world, all gardeners would have loamy soil. That is, the soil would have equal parts sand, silt and clay. Unfortunately, that is not the case. Some soils have a high percentage of sand which holds water and nutrients very poorly. Soils high in clay retain water and nutrients well but can be compacted and difficult to work with. By doing a very simple at-home soil test, gardeners can gain insight into the composition of their soil and create a better environment for garden plants.

Conducting a Home Soil Test

Materials needed for a soil test are basic and easily found around the home.

• A large glass jar with a tight-fitting lid
• 1 teaspoon of dish washing powder
• Ruler
• Calculator
• Soil sample
• The soil triangle

Collect a soil sample of about a cup from the center of the area to be tested. Take soil from approximately 3 to 4 inches deep. This is the depth at which plant roots will be. Remove any stones, twigs or other foreign objects from the sample.

Pour the soil sample into the jar along with the dish washing powder. Fill the jar with water and tightly close the lid. Shake the jar for about a minute until the soil, soap and water are well mixed. Place the jar on a level surface to allow the sediment to settle.

The largest particles, which are sand, will settle first, often within a few minutes. Next, the silt will settle on top of the sand and create a darker layer. The clay settles last and fairly slowly. Wait between 24-48 hours for all the particles to settle.

Analyzing the Soil Test

Once all the particles have settled, measure the height of the entire sample from the bottom of the jar to the top of the water level. Next measure each level of sediment. There should generally be a layer of sand, silt and clay. If there are only two visible layers, it is still possible to determine soil texture.

Next, take the height of each layer and divide that number by the total height of the sample. This gives the percentage of each type of sediment in the soil. Use the soil triangle to plot the percentages. Follow the arrows indicated on the sides of the triangle for each type to draw straight lines through the triangle. Where the line intersects is the type of soil present in that sample.

Improve Garden Soil

The ideal soil is in the loam section of the triangle and will have fairly equal amounts of the each of the three sediment types. This soil is ideal for water and nutrient retention and aeration and will be the easiest to work with. However, all soils can benefit from adding organic matter.

Sandy soils will be high in aeration but poor in water and nutrient retention. To improve sandy soil, add organic matter that will hold moisture and store nutrients. Good choices are compost or aged manure. Peat and vermiculite are also good amendments for improving water retention.

Clay soils are dense and compact easily. This soil holds water and nutrients well, but lacks aeration. Improve drainage by adding amendments such as peat, wood chips, tree bark or straw. Compost and perlite will also help clay soils.

It’s important to note that it is very difficult to permanently change soil composition. Adding sand to clay soils or clay to sandy soil is ill-advised and can result in rock hard soil. Proper soil amendments need to be added to clay and sandy soils on a regular basis to improve, but not change, soil.

This easy at home soil test can give gardeners a fairly accurate view into the composition of garden soil. By knowing the makeup of their soil, gardeners can better choose soil amendments to improve their soil and ultimately, their gardens.