Lawn and Garden Soil Testing
What is a soil test?
A soil test measures soil pH and available nutrients in the soil. It cannot identify insects, diseases, pesticide residues or chemical pollutants, and cannot answer questions about soil composition, drainage or compaction.
Why test the soil?
Testing the soil gives you accurate information about the type and amount of fertilizer or amendment to apply in order to maintain good plant health. Application of the appropriate type and amount of fertilizer helps protect the environment and can save you money and time.
When should soil be tested?
Lawn soils should be tested before planting, if possible. For established lawns, a test to evaluate basic fertility should be done. Thereafter, regular lawn maintenance fertilizer applications should be adequate.
Garden and flower bed soils should be tested every 3 to 5 years; annual tests are usually not required unless an extreme nutrient deficiency or imbalance is revealed. If organic fertilizer recommendations are desired, please indicate this when submitting the sample. If special plants, such as azaleas or blueberries, are to be grown, this should be indicated as well on the submission form.
How to take a good soil sample.
Test results will only be as reliable as the sample collected, so proper methods are important. Follow these steps:
- Using a clean shovel, trowel, spade or soil probe, dig down to a depth of:
3 to 4 inches for lawns
5 to 6 inches for vegetables, flowers and small fruits
10 to 12 inches for trees and shrubs
Note: It is important to obtain a representative sample of soil in the root zone rather than from surface soil.
- Take at least 4 to 5 samples from the area to be tested. Mix samples together in a clean container to create a composite sample. Remove all plant material or other debris. Avoid sampling overly wet soil - do not use heat to dry your sample.
- Place 2 cups of the mixed soil in a re-sealable, quart-size plastic bag. Label the bag with your name, address and the site from which the soil was collected.
- Create separate sample bags for each area you want tested - be sure to label each sample.
Soil Test Precautions
Do not contaminate the sample with soil from small areas which are abnormal or different, such as backfill ditches, trees or shrubs that have been given extra fertilizer, or areas where brush piles have been burned. If a lawn, garden or flower bed has two or more distinctly different types of soil, make separate samples.
Soil Test Request Form
Print the form listed below and answer all the questions as completely as possible. You will be given a specific recommendation based on the soil test results and information you have provided. To give you the best recommendation, we need to know about the plants being grown, past fertilization practices, soil amendments, mowing (turf) and any special problems in the test area. Printed forms are also available at the Extension Office.
Where to Bring the Sample
Bring the bagged soil, completed form and check/cash for the desired test(s) to the Shawnee County K-State Research and Extension Office, 1740 SW Western Avenue, Topeka, Kansas 66604 (phone 785-232-0062). Office hours are 8:00 a.m. to 5:00 p.m., Monday through Friday. Note: Make checks pay to - Shawnee County Extension Council.
Soil samples are sent to the Soil Testing Lab at Kansas State University. Their results will be reviewed by our Horticulture Extension Agent here in Shawnee County and a report with specific recommendations will be sent to you. The average time required for testing and analysis is 2 to 3 weeks. During peak months (March, April, May, August and September), this turn-around time may be longer.
Available Soil Tests and Fee Schedule
Many different analyses are conducted but the most common tests for Kansas soils are for pH, phosphorus (P), potassium (K), nitrate (NO3) and organic matter.
Package #1 (pH, Buffer pH, P, K) $10
This is the basic fertility test, sufficient for most homeowner lawns, gardens and beds.
Package #2 (pH, Buffer pH, P,K, NO3, organic matter) $14.50
This test is appropriate for soils that might have too much nitrogen or organic matter due to continuous heavy applications of fertilizer, compost or manure.
Package #3 (pH, Buffer pH, P, K, Zinc) $12.00
Organic Matter $2.50