The Value of Soil Testing Before Retiring a Garden

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When to calm a gardenFor the winter, it is best to allow for the amount of time that will be spent thinking about ways to improve the soil for the following year’s harvest. Healthy soil is the foundation of successful gardening, and a simple test can reveal the nutrient levels present and help strategize to improve its condition before the next growing season.

Why test the soil of a garden? Efforts to improve the garden soil are often blind; Fertilizers, lime, sulfur and other materials are added without knowing the existing nutritional status of a garden plot. This approach can be ineffective in improving plant growth and doing more harm than good to the soil and plants.

Plants generally respond better to an approach that addresses specific needs than to broad application of nutrients. The old adage “if a pound is good, two are better and three must be best” does not apply to fertilizers because if used indiscriminately it can burn the leaves of the plants. To adjust Nutrient applicationTailored to the needs of the plants can save money, prevent plant diseases and avoid unnecessary waste of nutrients that are washed away on the soil surface. A test can determine the current nutrient status of a soil sample and can provide insight into nutrient intake tailored to the needs of specific plants.

Which nutrients are tested? A general house and garden soil test analyzes the Soil pH, Organic matter content and phosphorus and potassium nutrient content. In addition, a test report can provide recommendations for appropriate nutrient application based on the particular crop to be planted. However, a test does not analyze the nitrogen content in the soil because the amount of this nutrient varies widely and the results cannot be accurately interpreted. (The University of Wisconsin Soil and Forage Laboratorycan test for other nutrients like calcium, magnesium, zinc, boron, or impurities like lead additional costs.)

When should the soil be examined? Fall is one of the best times of the year to test garden soil as it offers plenty of time to adjust the soil Soil pH. If the test indicates that more organic material is needed, CompostingAppropriate amounts of materials such as fallen leaves, readily available in the fall, can be started. Additionally, Wisconsin’s spring weather is often too wet to get a good soil sample core for testing.

How should a soil sample be taken? To ensure an accurate test result, it is important to take a good representative garden soil sample. Soil samples should be collected from at least 10 random locations that represent the entire garden plot. A soil probe, shovel, trowel or auger can be used to take samples. At each point, the sample core should be taken from a depth of 5 to 7 inches. For turf soil, samples can be taken at a depth of 4 inches. All of the collected soil sample cores should be mixed in a large container, and two cups of the mixed soil should be placed in a clean plastic bag.

The University of Wisconsin Extension recommends testing the garden soil every three to five years. Once a sample has been taken, it can be brought to one local expansion office. It can take about 10 business days for a soil test to be performed and a report to be generated.

Vijai Pandian is a horticultural agent and instructor for the University of Wisconsin Extension Brown County. This article is adapted from an article originally published from the Green Bay Press Gazette.

The Value of Soil Testing Before Retiring a Garden was originally published on WisContext who produced the article in a partnership between Wisconsin Public Radio and PBS Wisconsin.

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