How often have you seen a football field or another lawn area look worn, and wondered if you should fertilize it? I’m sure it’s happened to most of us. Then we pull out the tractor and spreaders, find some fertilizer lying around the shop that some salesmen told us to purchase because it’s the next-best thing to a perfect lawn, and send staff out to get it done.
Sometimes the results are not as spectacular as we hope, so we must look beyond the fertilizer bag. What is the soil telling you? What does it need to perform under the conditions that we expect it to endure, such as marching bands, football, soccer and baseball teams, camps and golfers?
Beneath The Surface
The first place to look is the soil. Without it, there would be no turf. Soil is not dirt--as one of my professors so profoundly told me in college, it is the root of all existence. Dirt is swept under the rug or out the door. Soil is a naturally occurring, unconsolidated or loose covering on the earth's surface; it is composed of broken rocks that have been altered by the environmental process of weathering and erosion. It is a mixture of minerals and organic matter from dying and decomposing living foliage.
So how do you determine if your soil is able to support turfgrass?
Where To Start
First, locate a soil laboratory in your area that has experience testing soils for turfgrasses. One reason to use a local laboratory is because it may already be familiar with your soil type and texture. In addition to private laboratories, most major land-grant universities can conduct the test. Your county extension office also may be a good resource. Once you have located a laboratory, ask an employee to send a description and price list of the various soil-testing procedures. That person also can supply the sampling bags needed to ship a soil sample for analysis.
Two Tools For Samples
Invest in a soil probe, a fairly inexpensive tool (from $45 to $200); a small planting trowel from the local hardware store also will work. Find a pail or bucket, and make sure it is clean. You wouldn't believe how many people use a dirty bucket to collect samples. This may result in the test coming back with a bad recommendation due to the contents that were previously stored in the bucket.
Now, start taking samples. With the probe, only go into the ground 2 to 4 inches. Since you are trying to determine what nutrients are available to the turfgrass plant, you are only concerned with the soil that the roots are in, which is the top profile of the soil. When sampling an athletic field, remember to take samples from the entire field--about 20 to 40 soil plugs. With the bucket and probe, walk the field in a straight line back and forth while randomly taking samples. Before putting them in the bucket, tear the grass plant from the soil and throw it away. The laboratory does not need the plant tissue--only the soil. All 20 to 40 samples for one field go into the same bucket.
Back at the shop, mix all the soil samples from the field together to make one deposit of soil. Once mixed thoroughly, pour the entire bucket onto a clean table or other flat surface, and allow the contents to dry. Place the sample in one of the bags from the laboratory; seal it and mark on it which field you have taken it from. You can develop a code for each sample. I usually mark the bag with the initials of the golf course it came from and the tee, green or fairway (e.g., S.H. 2 T stands for Sleepy Hollow #2 Tee).
Pay attention to the forms the soil laboratory sends. These forms ask for information that the testing laboratory needs to give an accurate report. You will most likely be asked to assign a sample identification number, as well as the plant type you are testing (Bluegrass, Ryegrass, Bentgrass, etc.); if it is a mixture of two or more grasses, let the lab know. Also note the area type (football field, golf green, playground).
Once the laboratory receives a sample, it will take from 7 to 14 days to provide results.
Information in the report will include the pH, the results of the analysis (pounds per acre of available nutrients), cation exchange capacity and calculated values (percent-base saturation). There may be a graph to display average results, and then the laboratory will give its recommendations.
The first time looking over a soil report can be intimidating. The levels listed on the form can provide a wealth of information--but only if the terminology and processes involved are fully understood; that's why it’s important to select a reputable laboratory to help you interpret the report. If you don't understand the report, call the lab; it will be glad to help.
One final word of caution: I know some fertilizers sales people offer to do soil samples for free, and that is a nice service, especially when budgets are becoming tighter. But sometimes it pays to obtain a non-biased result from a laboratory that has nothing to gain from the results--other than maybe more testing.
Sean McHugh , CGCS, is director of Golf/Turf for Cleveland Metroparks. He can be reached via e-mail at firstname.lastname@example.org