When preparing your spring garden don’t forget to soil test

Published 12:00 am Saturday, February 18, 2012

Before you know it spring will be here, and many will be wishing they had started preparing their garden a little earlier. One of the most important steps to take in preparing the garden is to have the soil tested. Soil can be brought to your parish LSU Ag Center Office to be tested. The Routine Soil Test costs $10. Test results will usually arrive in 10-14 days.

A soil test will tell what the pH is of the soil and what needs to done to change the pH level. Most plants grow best in a pH range of 6.0 to 6.5. Soils that have not been limed for several years may have a pH well below 6.0 while some soils may actually have a pH of 6.8 or higher. Lime, which contains nutrients like calcium, phosphorous and magnesium, is used to raise the pH level, while sulphur is usually used to lower the pH level. It is important to get the soil tested early because if lime is needed to increase the pH, it will take several months for the lime to break down to a form that can be used by the plants.

Most fertilizers that are used in the garden contain are called complete fertilizers because they contain the three nutrients that plants use the most – nitrogen, phosphorous and potassium. When a container of fertilizer is purchased, always look on the container, be it a box, a bag or a bottle, and see how much of each of these nutrients is contained in the fertilizer. The nutrient amounts are listed in percentages and always in the same order – nitrogen first, followed by phosphorous and finally potassium. A fertilizer listed as 13-13-13 would contain 13 percent nitrogen, 13 percent phosphorous and 13 percent potassium. I am sure that everyone remembers from school their chemical symbols from the Periodic Table – nitrogen is “N,” phosphorous is “Ph” and potassium is “K.” Complete fertilizers may be sold in many different percentages like 0-24-24, 8-24-24, 8-8-8, etc. If just nitrogen is needed, it can usually be purchased as ammonium nitrate or ammonium sulfate.

One key thing to remember about using fertilizer is that if too much nitrogen is used, it could possibly kill the plant, so make sure that the recommended rates are followed. Plants in the legume family like clover, peas and beans have the ability to manufacture their own nitrogen on their roots, so these plants require less nitrogen than other plants.

To send off a soil to the Soil Lab at LSU, collect about one pint of soil for testing. This soil sample is taken from the top 4-6 inches of the soil. Be sure to remove any grass clippings, plant parts or woody materials. Do not collect soil when it is extremely wet. The key to taking a good soil sample is to make sure the sample of soil truly represents the soil in the garden. The best way to accomplish this is to take as many as five or more samples from throughout your garden area and place them all in a bucket. Then mix them up thoroughly and take out at least one pint of soil from the bucket and place it in a plastic storage bag or other container. Remember, at least one pint of soil is needed for the test.

Bring the soil sample to your local parish LSU Ag Center Office. LSU Ag Center personnel will package your soil sample and have you complete a Soil Test Form, which includes your mailing address as well as information on what type of plants or vegetables you plan to grow. This form along with your $10 payment for each sample will be packaged with the soil and sent to the LSU Soil Lab where it will be tested. After the test is complete the Soil Lab will mail or email you a copy of the test results. Your local county agent will also receive a copy of your soil test via the computer. If you do not understand the results of your soil test, you should call, visit or email your county agent and discuss the results with him. Your county agent can help you to understand your test results so you can get the most benefit from your garden. With a little help you can grow an abundance of vegetables in your garden.

For more information on starting a garden, visit the LSU Ag Center’s website at lsuagcenter.com. Your local LSU Ag Center parish county agent can also answer your questions on gardening.

If you have any questions, please contact your local LSU Ag Center County Agent. You can contact David Pichon, County Agent-St. John Parish at 985-497-3261 or by email at dpichon@agctr.lsu.edu.