Knowing what is in your soil and what nutrients it needs are basic first steps for healthy plants and a good crop, according to LSU AgCenter horticulturist Dr. Tom Koske. Plants depend on soil for their food.
"We must manage that soil for best growth" Koske says, noting, "Fall is a great time to do a soil test. It beats the spring rush and gives you time to find and apply what is needed."
If lime is needed to raise the soil pH, for example, it should be applied several months ahead of time to take effect. If applied in warm weather, it can cause root or plant burning.
A fall soil test also can tell you how well you came through the growing season. Fall test values should come out mid-range to show that your fertility program was adequate and not too strong or weak. Too strong a fertility program will cause a buildup of nutrients to test high or very high by fall.
"It’s not like having ‘too much’ money in the bank," Koske says, explaining, "High fertility actually can lead to growth problems." Too weak a program shows low to very low fall values. Low values indicate that you ran out of good fertility before the end of the growing season and may have weakened the plants.
The LSU AgCenter tests soils for potassium, phosphorus, calcium, magnesium and pH among other values. These major nutrients fuel growth along with nitrogen.
"Since nitrogen is so transient, we just advise on its use, based on soil type and crop," Koske says. If your soil is similar throughout the property, one composite sample from the 4-inch to 6-inch profile can be used to make recommendations on several crops. List all the crops you will want fertilizer recommendations for that will grow in that soil sample type.
Soil samples may be brought to the local LSU Ag Center extension office, participating garden centers or taken directly to the LSU soil test lab in Sturgis Hall in Baton Rouge. There is a small charge for this testing, and results can be e-mailed to you.
For more information on the soil testing service, call your local county agricultural agent or go to www.lsuagcenter.com/stpal. For related topics, look for Gardening and Get It Growing links in the Feature section of the LSU AgCenter Web site: www.lsuagcenter.com.