Soil Testing is Key to a Healthy Garden

Home Grown  by Keith Reed
A healthy garden soil is one of the most important factors (at least among those that the gardener has some control) in determining the potential success of a garden.

A basic soil test is the best place to begin improving your garden soil. If you are a regular reader of Extension gardening information, you have seen and heard us talk about this many, many times. Not only does our office review and make recommendations on hundreds of soil test results each year, we regularly assist clients with a variety of plant problems that are caused by nutrient deficiencies.

Soil testing is a local issue as soil conditions vary widely across Oklahoma. For residents of Payne County, a few trends quickly emerge when looking at all these soil test results.

The majority of area gardeners do not need to be adding phosphorus to their soil. This is especially true if you have been using a garden center staple such as 10-20-10 for years. Phosphorus (the 20% in the 10-20-10) causes problems with runoff into our rivers and lakes, leading to imbalances and unhealthy moss and algae growth. In 2012, at least 11 states had restrictions on the application of phosphorus as a fertilizer because of this problem. As Oklahomans, let’s not force that restriction on ourselves. Unless your soil test says you need phosphorus, please do not apply it.

Another issue we see is soil pH outside the range for optimal growing conditions. Almost all garden and landscape plants perform best in a relatively narrow range of between 6 and 7.5. In the Payne County office, we regularly see pH values between 4.2 and 8.6. At these extremes, fertilizer application is a waste of resources as some critical nutrients are not available to the plant, no matter the fertilizer rate. In these cases, pH correction must occur for healthy growth. This can be done relatively easily through the application of lime (if the pH is too low) or sulfur (if too high).

While application of lime or sulfur is straightforward, it does take some time (months) for these changes to begin to occur. In other words, right now is an excellent time to take a soil sample for your garden or landscape so that it is ready to go this spring.

For more information on this or any other horticultural topic, you can contact Keith Reed, the Horticulturist in the Payne County Extension office. Keith can be reached via email at, phone at 405-747-8320, or in person at the Payne County Extension office, located at 315 W. 6th in Stillwater.

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