Soil test kits area available through most lab suppliers and can be used in school science to determine the acidity of the soil or find nutrients present.
Kits which can determine nutrients present in the soil may be called NPK kits with the letters indicating nitrogen (N), phosphorus (P) and potassium (K), the three most common soil nutrients. Other kits may test specifically for the pH of the soil.
When conducting a soil test the following points should be considered.
Sample depth - the depth of the soil where the samples are taken from should be consistent to give a fair test. 'tillage' or planting depth is a good depth to take samples from. At this level there are generally more nutrients present in the soil and is deep enough not to be so heavily contaminated by outside factors.
Sample storage - Soil samples should be tested on site if possible. If not, it should be tested as soon as is possible in the lab. Characteristics in the soil may change over time and may give differing results compared to freshly sampled soil.
Sample variance - Over a large area such as a school field, soil quality and characteristics can very greatly. Areas near paths or roads can be contaminated by salt and lime. Areas beneath trees or bushes may contain vastly different levels of nutrients. Taking many samples and producing an average may give a more useful result.
Tools - Tools and sampling equipment should be cleaned using distilled water before each use so as not to contaminate the sample and give potentially false results.
Some soil test kits can detect nutrients - nitrogen (N), phosphorus (P), and potassium (K), secondary nutrients - sulfur, calcium, magnesium, minor nutrients - iron, manganese, copper, zinc, boron, molybdenum, aluminum, and physical properties - soil acidity, electrical conductivity, soil organic matter, moisture content, and soil contaminants.
Most schools will use the kits for simple sampling although specialist kits and equipment can be purchased which can be used to detect these secondary nutrients and properties.