Oklahoma Alfalfa
Oklahoma Cooperative Extension Service
Oklahoma Agricultural Experiment Station

 SOIL TEST IN SPRING & EARLY SUMMER 
For Warm-Season Grasses & Fall Alfalfa Establishment

Now is the time of year to soil test and fertilize warm-season grass pastures and hayfields. Collect representative samples from your fields. Submit them to the Soil, Water and Forage Analytical Lab through your county cooperative extension office.   

If you tested the field last year or the year before, review the results and apply fertilizer as recommended. Remember, phosphorus and potassium recommendations are reported on an annual basis. The phosphorus and potassium rates need to be applied every year until another soil test is performed. Nitrogen rates, on the other hand, are determined by yield goal, and test results do not carryover from year to year, therefore, annual soil testing may be needed for non-legume forage.   

Farmers planning to establish alfalfa in the fall should soil test their fields now to make sure the soil pH is not too acid. If lime is required, it should be applied and incorporated as soon as possible to give it time to react with soil and raise soil pH. See OSU Extension Facts No. 2229 for more details about liming.