Soil Sampling & Testing Advanced Soils Topics for Master Gardeners Amy Shober UF-IFAS Gulf Coast REC 1 of 13 ©2008 University of Florida-IFAS

Tools for Collecting Soil Plastic bucket Shovel or soil probe Paper bag or newspaper for drying Soil test sample bag 2 of 13 ©2008 University of Florida-IFAS

Taking a Soil Sample Representative area Sample the root zone depth Take & mix several cores together Do not mix cores from “good” & “bad” areas 3 of 13 ©2008 University of Florida-IFAS Figure Credit: Amy Shober, UF-IFAS

ESTL Recommendations TurfgrassOrnamentals/Vegetables BahiagrassAzaleas BermudagrassBlueberries CarpetgrassCamellias CentipedegrassDooryard Citrus RyegrassGardenia St. AugustinegrassHibiscus ZoysiagrassIxora Woody ornamentals (general) Vegetables 4 of 13 ©2008 University of Florida-IFAS

UF-ESTL Available Tests Test A ($3.00) pH Lime requirement Test B ($7.00) Test A + P, K, Mg 5 of 13 ©2008 University of Florida-IFAS Photo Credit: Amy Shober, UF-IFAS

pH vs. Lime Requirement Soil pH Test Measures active acidity –pH that affects plant growth Lime Requirement Test Also called buffer pH Measures reserve acidity Uses a liming solution Compared to soil pH Measures how easily pH can be changed –Bigger change means easier to change pH 6 of 13 ©2008 University of Florida-IFAS Photo Credit: Amy Shober, UF-IFAS

Why Measure Buffer pH? Active acidity(solution) and reserve acidity (bound to clay and OM particles) 7 of 13 ©2008 University of Florida-IFAS Figure Credit: James Bonczek, UF-IFAS

Why Measure Buffer pH? Lime (calcium carbonate) neutralizes acid in the soil solution & pH increases. 8 of 13 ©2008 University of Florida-IFAS Figure Credit: James Bonczek, UF-IFAS

Why Measure Buffer pH? Ca 2+ displaces H + on the surface of clays or OM and pH drops back down. 9 of 13 ©2008 University of Florida-IFAS Figure Credit: James Bonczek, UF-IFAS

Testing Soils for Plant Available Nutrients Chemical extractants are used UF-IFAS uses the Mehlich 1 extractant –Developed by Dr. Adolph Mehlich (NC) – Good for P, K, Ca, Mg, Zn, Mn, and B – Good for acid, low fertility soils Nitrogen testing not available due to dynamic nature of N 10 of 13 ©2008 University of Florida-IFAS

Soil Test Results Soil Test Phosphorus (Lbs/Acre) Relative Yield (%) 11 of 13 ©2008 University of Florida-IFAS

The Soil Test Report 12 of 13 ©2008 University of Florida-IFAS Figure Credit: UF-IFAS Extension Soil Testing Lab Read the whole report! No lime recommended Recommendations (per 1000 sq. ft) –2.3 lbs N –0.4 lbs P 2 O 5 –1.4 lbs K 2 O

Summary Soils should be tested prior to applying fertilizers or lime. If you are planning to raise your soil pH, have a lime requirement test run. Soil samples can be analyzed by the University of Florida – IFAS Extension Soil Testing Lab (or other reputable lab). Always read the entire soil test report. 13 of 13 ©2008 University of Florida-IFAS