[header] How to feed a warm season lawn [title] Take a soil sample of your lawn. [step] A soil sample will give you an evaluation of the nutrients and determine what amendments or fertilizers will work best for your lawn. To take a sample, use a gardening spade and dig 5 holes that are 6-8 inches (15-20 cm) deep in several areas of your lawn. 
Put the soil that you unearthed in a clear container and send it to your nearest cooperative extension. [substeps] You can take samples of your soil annually to keep up with the changes in nutrient content.