Most of us mistakenly think that soil testing is only for new gardens – but we are wrong. According to the University of Maine Extension services, even established gardens need soil testing every 3 to 5 years because soil changes over time.
There are two alternatives for testing the soil – home soil tests and a soil testing service. Both have their place, but there are significant differences between the two. Here’s what to expect from each.
Home soil tests. These tests are inexpensive and can be purchased in hardware stores or home improvement centers. They are typically located near the plant supplies and sell for a few dollars. These soil tests contain tiny vials for the soil and colored capsules containing powder for testing the soil. They assess the amount of nitrogen, phosphorus and potassium in the soil and test the soil pH. They provide general instructions for amending the soil. Home soil tests give you a good idea of the nutrients in your soil, but rely on the color of the solution (after adding soil) to the colors on a chart. The charts are notorious for being off-color and difficult to read.
Soil testing Services: Many Universities (including the University of Maine Extension) provide soil-testing services for a reasonable fee. Current rates (2012) for the University of Maine soil testing is $15 for a standard test and $22 for a comprehensive test. You can indicate the type of crop – or garden (organic or inorganic) – you wish to grow. The test results will provide you with specific recommendations for amending the soil for your desired use.
Whether you need a quick test to determine the pH of your soil or a comprehensive test to determine the overall condition of your soil determines which test you should choose. Fall testing is recommended because it gives soil amendments time to work their magic before gardening season begins in the spring.