Soil Analysis for Producers & Homeowners

Samples that come into the lab are dried in an oven overnight and ground with a pulverizing-type grinder the next morning. The bulk of analysis will be completed after grinding or the following day. Once the data is complete and has been reviewed, sample information sheets are printed and mailed to the producer.

Samples are kept on storage shelves for a time so samples may be available for additional analysis by request.

Soil Sample Collection

Sample collection will vary depending on the tests being conducted and the type of soil being collected. Please label all samples and completely fill out the sample information sheets so lab analysis and processing can occur efficiently.

Before you get started, please read these tips for a successful soil sample collection:

  • On long term reduced till or no-till fields, a split sample from the top 6 inches (i.e. 0 to 3 inches and 3 to 6 inches) is encouraged to assess pH and nutrient stratification near the surface.
  • All row crops should be sampled to 6 inch depth and all permanent sod to 4 inches.
  • For available nitrogen, chloride, or sulfur tests, please gather a sample of soil from 24 inches.
  • For the zinc test, collect soil samples in a plastic container to avoid contamination from galvanized buckets or material made of rubber.
  • Avoid sampling in old fence rows, dead furrows, low spots, feeding areas, and other areas that might give unusual results.
  • Do not use heat for drying.

You will need:

Field Grid

Step 1

Draw a map of the area to be sampled on the information sheet and divide your fields into uniform areas. Each area should have the same soil texture, color, slope, and previous fertilization and cropping history.

Sample Depth

Step 2

From each area, take a sample consisting of 20 to 30 cores or slices, mix thoroughly in a clean container, and then fill your soil container from this mixture.

Soil Sample Labels

Step 3

Be sure to label the soil container clearly with a Sample ID and record each Sample ID on the information sheet.

Air Dry Samples

Step 4

Air dry samples as soon as possible for the nitrogen test. Air drying samples that will be shipped is also desirable.


Available Tests for Producers

The various tests available from the soil testing laboratory are described below. Read the description of each test and mark on the information sheet which tests you desire on your samples. Review our most recent pricelist for a summary of available tests.

Routine Fertility

This test is recommended where crops grow normally, but you desire to know the amount of lime, if any, and the kind and amount of fertilizer needed for optimum plant growth. The test includes determinations for pH, lime requirement on those samples with a pH of 6.4 or less, available phosphorus and exchangeable potassium. On a majority of the soils in Kansas, this test will be adequate. The results of the general fertility test may be supplemented by one or more of the tests listed below.

Profile Nitrogen

This test is recommended on areas that are suspected of having appreciable residual inorganic nitrogen (nitrates). Continuous heavy applications of commercial nitrogen fertilizer and/or heavy rates of manure may result in residual available nitrogen, especially where yields have not been proportional to the nitrogen applied. Under summer fallow conditions, appreciable quantities also may accumulate. Because nitrates are water soluble, movement of the nitrates down in the profile will occur when moisture penetrates into the soil.

Thus, sampling for the available nitrogen test should include subsoil samples to depths deeper than the tillage layer. A surface soil sample (0 to 6 inches) plus a subsoil sample (6 to 24 inches) should be taken. The samples must be air dried as soon as possible to stop microbial activity. This means spreading the sample on a clean sheet of paper or plastic to dry before sending the sample to the laboratory. Caution: Be sure the sample is not contaminated by fertilizer dust, manure, salt, etc. Samples should be dried within 24 hours.

Available Zinc

This test is recommended on areas with high yield potential for corn or soybeans, which by erosion, terracing, or leveling for irrigation have had the topsoil removed. Sandy soils, low in organic matter, under high yield conditions also should be checked for zinc. Wheat, alfalfa, grain sorghum, and pastures are not likely to respond to zinc so this test is not recommended for these crops.

Available Iron

This test is recommended on the calcareous soils of the western part of the state to determine the likelihood of iron chlorosis on grain sorghum, soybeans, and corn. The test also can be beneficial for selection of shrubs, etc. around homes.

KCl Extractable Aluminum

Extremely acid soils (pH of 5 or less) may contain appreciable KCl extractable aluminum, which is very toxic to plant roots. This test is recommended for use where extremely low pH's are found and lime is not immediately available for spreading. The test results also are helpful in diagnosing problems of poor plant growth.

Profile Sulfate-Sulfur

The majority of the sulfur in the soil is in the organic fraction and is microbially mineralized to the sulfate form for plant utilization. For interpretation of the sulfate-sulfur test, soil organic matter and texture also need to be known. Therefore, the organic matter test needs to be requested and texture reported on the information sheet. Sulfur deficiency is most likely to be found on low organic matter, very sandy soils. Samples should be to a depth of 24 inches.

Available Profile Chlorides

Wheat has been shown to respond to chloride application. Because the chloride ion is quite soluble and, therefore, mobile, soil samples to a depth of 24 inches is recommended. Chloride research with crops other than wheat is in progress, but no interpretation of profile chloride results are available for any crops other than wheat.

Organic Matter

Organic matter in the soil is the storehouse of most of the nitrogen, sulfur, and several of the micronutrients. Organic matter results can be very meaningful to agronomists in better understanding the soil conditions on your farm. Organic matter levels can be useful in determining rates of herbicides. This test is not recommended on all samples, but only in cases where the additional information is desired

Soil Testing Laboratory

K-State Research and Extension
2308 Throckmorton PSC
1712 Claflin Road
Manhattan, KS 66506-5503

Ph: +1-785-532-7897

Lab Hours: 

Mon-Fri 8am-5pm