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Fall and spring are the times when the labs get flooded with soil samples for testing. However, fall sampling is ideal for farmers as it gives the starting point to plan for next year's nutrient management plan. If you are going to apply nutrients you need to know how much to put on. Without soil testing, nutrient applications are a guess, and there is no room for guessing in today's atmosphere of narrow margins due to high fertilizer prices, and public concern of the environmental pollution. Testing soils reduce the risks involved with applying nutrients. What kind of fertilizer do you need to achieve your yield goals? Well, a good place to start would be University of Missouri Soil and Plant Testing Lab.

Soil testing is a farmer's best guide to the wise and efficient use of fertilizer and soil amendments. A soil test is like taking an inventory of the nutrients available to plants, which are too high, too low or just right. While plant growth and prior yields may offer clues to nutrient availability, a farmer won't precisely know until they test their soil. Although soil-testing kits are available in the market, laboratory testing is more reliable, and the results from laboratories are accompanied with interpretations and recommendations.

Why Do Soil Test? Soil fertility fluctuates throughout the growing season each year. The quantity and availability of mineral nutrients are altered by the addition of fertilizers, manure, and lime in addition to leaching and de-nitrification losses. Furthermore, large quantities of mineral nutrients are removed from soils as a result of plant growth and development, and by the harvesting of crops. The soil test will determine the current fertility status. It also provides the necessary information needed to maintain the optimum fertility year after year.

The soil test takes the guesswork out of fertilization and is extremely cost effective. It not only eliminates the waste of money spent on unnecessary fertilizers, but also eliminates overusage of fertilizers, hence helping to protect the environment.

When Do I Soil Test? : Although fall and early spring are typical times to test soil, one can really do it any time the soil is not frozen, but don't sample after recent fertilizer or lime applications. For new sites, soil samples can be taken anytime when the soil is workable. Most people conduct their soil tests in the spring. However, fall is a preferred time to take soil tests if one wants to avoid the spring rush. Fall soil testing will allow you ample time to apply lime to raise the soil pH.

Soil testing is strongly recommended for field crops. The cost of soil testing is minor in comparison to the cost of seed and plants and labor. Correcting a problem before planting is much simpler and cheaper than afterwards. Routine fertilizer or lime applications can result in excessive soil nutrient levels or deleterious soil pH. For example many fertilizers tend to have lower soil pH, and after several years of fertilization the pH may drop below desirable.

The test results are only as good as the sample taken. It is extremely important to provide a representative sample to the testing lab so that a reliable test and recommendations can be made for the entire area. This can be accomplished by submitting a composite sample. Take 15 random samples in a zigzag pattern at plow depth, mix well, and submit a sub-sample from it to the lab. We recommend that you divide your field and submit one sample for each 40 acres.

Testing your soil for nutrients and pH is important to provide balanced application of nutrients, while avoiding over application. At University of Missouri Soil Testing Laboratory we offer a regular fertility test that includes measurements of pH, lime requirement, organic matter, available phosphorus, potassium, calcium, magnesium, and cation exchange capacity. Soil pH greatly influences plant nutrient availability. Adjusting pH often corrects the nutrient problem for most plants. The optimum pH for most plants is between 6.0 and 7.0. The lime requirement measurement indicates the amount of amendment (usually lime) necessary to correct a pH problem. Organic matter has several roles in the soil; generally the more organic matter the better. Nitrogen recommendations are based on the organic matter level. Phosphorus, potassium, calcium, and magnesium are all essential plant nutrients. The cation exchange capacity (CEC) value is a measure of the soil's ability to hold nutrients.

Test costs vary according to the number of nutrients tested. The University of Missouri Soil Testing Laboratory charges $10.00 (when submitting direct to the lab) for a regular fertility test. Special services and prices are available when submitting large numbers of soil samples for Precision Ag purposes (40 or more samples submitted by one person at one time). Please contact the lab or visit the lab's website ( http://soilplantlab.missouri.edu/soil) to get specific information on pricing and services. Several other analyses are available. These include but are not limited to soil analysis for sulfur, micro-nutrients (Zinc, Iron, Copper, Manganese, Boron), salt content (electrical conductivity), and soil texture (particle size analysis). Test reports provide interpretation and nutrient recommendations. The turnaround time for a regular fertility soil test is 24 hours from the time sample is received by the lab. Customers have to add mailing time to get the reports by regular mail services. For plant, manure, water, greenhouse media and compost tests the turnaround time is within 5 working days.

You can contact your Regional Agronomy/Horticulture/ Natural Resources Specialist or local Extension Office to obtain Sample Information Forms and sample boxes, and can submit samples through their offices. These Regional Specialists at your local Extension Offices can be a source of information for interpreting and personalizing your soil test reports and recommendations. Samples can be submitted directly to the University of Missouri Soil Testing labs at 23 Mumford Hall, Columbia, MO 65211 (Tel: 573-882-0623)

The lab maintains a comprehensive web site at http://soilplantlab.missouri.edu/soil. The site includes information on how to collect soil and plant samples, and how and where to submit samples. The web site provides a list of services provided by the lab, costs of tests, sample information forms, location of the lab and other relevant information. Now the lab also provides web access of soil test results with a specifically assigned password to clients upon request. We also have the option for electronic mailing of data if required. Customers can drop off their samples in person at 23 Mumford Hall, mail them in, or drop them off at their County University Extension offices.

Dr. Manjula Nathan
Director MU Soil Testing & Plant Diagnostic Service Laboratories