Soil Testing in Minnesota

Overview

The best growth of grass, flowers, fruits and vegetables depends on many factors. One of these factors involves soil condition. There are 17 essential elements needed in the soil to promote healthy growth of grass and plants. Soil can be tested to determine which of these elements are present and which are missing. The control of these elements maybe required to keep the soil in good growing condition for Minnesota yards.

A Soil Test

A soil test is a method of analyzing soil to determine which nutrients are present. Soil tests can be performed on lawns and gardens or on professional turf. Lawn and garden testing provides the basis to maintaining a healthy lawn or garden. The University of Minnesota Testing Soil Laboratory will test soil samples from around the state. Local county extension offices throughout the state accept samples and send them to the laboratory. The most basic tests include soil texture category, pH and lime requirements, phosphorous and potassium content. Other more specific tests can be performed upon request.

How to Provide a Test Sample

A soil test result is no better than the sample submitted. For that reason, careful collection of samples is critically important. When a soil test is request from the University of Minnesota, the laboratory sends out careful instructions of how to obtain the soil sample. There are three things associated with obtaining the sample; when, where and how. The sample should be obtained at a time when the soil conditions permit. In Minnesota this is typically spring and summer when the ground is not frozen. Where the sample comes from depends on if there is variability between different spots in the yard--it may be different in the front yard and the back yard. You should not mix soil from a lawn area with soil from a garden area in the same sample. How to obtain the sample involves removing any surface litter or top grass. Sampling depths depend on the condition of the yard. Existing yard samples should be dug 0 to 3 inches while new grass samples should be dug 0 to 6 inches deep. Put the samples in a clean container and take samples from five different areas around the lawn. Mix the five samples together and send it in to the laboratory.

Soil pH

The pH determines the acidity in the soil. The pH number is a ratio of acid to base elements in the soil. A ph of 7 is neutral, less than 7 is acidic, and higher than 7 is alkaline. Add lime if acidity is low. Lime adjusts soil chemistry but is not a fertilizer. Adding too much lime can cause damage as well. Most plants have a range of pH in which they grow best. It is important to know how to prepare the soil for certain plants.

Macronutrients

Nitrogen is not specifically tested for because it is very transportable in soil. The general test is based on the overall organic level matter in the soil. However, nitrogen (N) is the most important of all essential nutrients. Soil can contain large amounts of nitrogen but it may not use it efficiently. It is available in two forms, ammonium and nitrate. Commonly, ammonium is quickly converted to nitrate and easily dissolved in water. Therefore timing and rates of nitrogen fertilization are important. For sandy soil, nitrogen should be applied early in the season. Apply nitrogen in smaller applications on sandy soils. Phosphorous (P) is extracted, determined, and reported in parts per million (ppm). Phosphorous is vital in plant growth and photosynthesis. Phosphorous provides energy transfer and storage and helps plants use water efficiently. Potassium is reported as parts per million and is absorbed by the soil in larger amounts than other nutrients. It helps in building protein and with reducing diseases in plants.

Significance

Once these tests determine the soil content of nutrients, the extension office will give recommendations on how to change existing soil into prime conditions for lawns and gardens. Soil tests are important in preventing over fertilizing or using the wrong products that will not achieve desired results. Soil tests can determine why lawns are not growing or greening up. They can determine if plants are not growing because they are missing essential nutrients. Amendment recommendations will be made according to the results of the tests. These types of results are specific to Minnesota and its soil types. They provide resources not only for better lawn and garden care but for environmentally safer practices to maximize growing potential.

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About this Author

Sheri Engstrom has been writing for 15 years. She is currently a gardening writer for Demand Studios. Engstrom completed the master gardener program at the University of Minnesota Extension service. She is published in their book "The Best Plants for 30 Tough Sites." She is also the online education examiner Minneapolis for Examiner.com.