Soil testing is the chemical and physical analysis of soil to assess its nutrient content, pH level, Composting percentage, and texture. Regular testing allows land managers to make informed decisions about fertilization, liming, and amendment applications. Standard soil tests measure the availability of nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, and micronutrients such as zinc, manganese, and boron. Tests also report cation exchange capacity, which indicates the soil's ability to hold positively charged nutrients.
A representative soil sample requires collecting 10 to 15 subsamples from a uniform area, mixed together into a single composite sample. Samples are taken from the top 15 to 20 centimeters (6 to 8 inches) of soil for gardens and row crops, or 10 centimeters (4 inches) for permanent pasture. Separate samples should be collected from areas that differ visibly in soil type, drainage, cropping history, or slope. Tools include stainless steel soil probes, augers, or clean spades.
Soil test reports provide a numerical value and an interpretive rating: very low, low, medium, high, or very high. Optimal ranges vary by crop. Test results include specific fertilizer recommendations based on the target crop and the soil's existing nutrient levels. The pH scale runs from 0 to 14, with most garden crops performing best between pH 6.0 and 7.0. Soil pH Management addresses how to raise or lower pH toward these targets.
Soil tests performed every 2 to 3 years are sufficient for most garden and field soils. New garden sites should be tested at least one season before planting. Annual testing is recommended for intensive vegetable production, high-value crops, or soils with known nutrient imbalances.