Conservation Notes: Soil Sampling

10/19/2010 10:12

Nitrogen, phosphorus and potassium are nutrients essential to plant growth. Over-application of nutrients is not good for plants or the environment. Nutrients may leach through the soil and into the groundwater or run off into storm drains. Soil testing measures the nutrient level of the soil and promotes proper nutrient management. For those who fertilize lawns or gardens, soil testing prevents over-application of nutrients and assists in the application of the proper amount of required nutrients.

Proper soil sampling is important to an accurate soil test. How do you take a soil sample? A soil probe, bucket, shovel and a soil sample bag are tools needed for collecting a sample. Determine how many samples are needed per field. Take in consideration soil types, soil texture, slopes, and drainage. Collect a sample of 12 to 20 cores using a soil probe at random or in a grid pattern. A core is an individual boring at one spot in the field. Make sure the area being sampled is well represented. One composite sample should be collected per five acres. Alfalfa and clover need to be sampled at a depth of 0 to 6 inches. Corn, soybeans, wheat and oats need to be tested at a depth of 0 to 6 inches and 6 to 24 inches. Mark the location of the core sampling on a map and label the soil sample accordingly. For soil sampling a lawn, a core should be taken at a depth of 4 inches. Be sure to remove sod from the sample. A core should be taken at a depth of 7 inches for a garden, as well as for underneath trees and shrubs. Take five soil cores per sample. Keep samples of "problem areas" separate so they can be tested. To make a composite soil sample, mix the cores thoroughly in a clean plastic bucket. Soil samples should be stored in a cool area until they are sent to the soil laboratory. Deliver your soil samples to your local fertilizer dealer or soil laboratory for analysis.

Soil Testing kits for lawns and gardens are available for purchase at the Henry County Soil and Water Conservation District. Soil testing kits are $25 each. Included in the kit are soil sampling instructions, soil probe, and sample bag. A report on the analysis of the soil will consist of pH, phosphorus, potassium, calcium, magnesium, organic matter and cation exchange capacity. Along with the results, will be a fertlilzer recommendation and information on lawn and garden fertilisty. Contact the Henry County Soil and Water Conservation District at 309.937.5263 or visit for more information regarding the soil testing kits. Know where you stand.

- Monica Stevens, Resource Conservationist