Understanding Potassium and Sulfur in Soil for Effective Fertilization
Explore the essential information on potassium and sulfur in soil, including their characteristics, testing methods, fertilizer sources, and implications for plant health. Learn about the importance of these nutrients, common soil conditions affecting their availability, and best practices for optimizing crop productivity through proper fertilization.
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Presentation Transcript
Soil 4234 Lab Soil 4234 Lab # 11 Fall 2016 Fall 2016 # 11 Soil Test for Potassium Soil Test for Potassium and Sulfur and Sulfur
Potassium Facts Potassium is immobile in the soil, and mobile in the plant Second most abundant nutrient in the plant. Taken up as K+ o Remains in that inorganic form in the plant. Soil test values are typically higher in o Drier climates o Soils with high shrink-swell clays In Oklahoma, most fertilization is required in areas of high biomass removal systems o Alfalfa, improved Bermuda grass
Potassium Soil Test Mehlich III Extractant 10:1 extractant: oven dried soil ratio Shaken for 5 minutes Filtrate analyzed on ICAP or AA Concentration reported as Soil Test K Index Sources of Error o High shrink-swell clays fix K+ in the clay inter layers in extremely dry years
Potassium Fertilizer Sources Muriate of Potash KCl o 60 62 percent K2O
Sulfur Facts Sulfur is mobile in the soil, and immobile in the plant. Taken up as SO42- o Used in the formation of two amino acids in the plant. Because it is mobile in the soil, fertilizer recommendations are based on yield goals. o 20:1 ration of N applied/S applied (non-legumes) Surface and subsurface soil sampling required. Deficiencies usually only seen in sandy soils with low soil organic matter.
Sulfur Soil Test Extractant = Calcium Monophosphate 2.5 : 1 extract : oven dried soil ratio Shake for at least 30 minutes Filtrate analyzed on ICAP Concentration reported as lbs S/ac
Sulfur Fertilizer Source Gypsum CaSO4 + 2H2O o 17 % sulfur o Not very water soluble Ammonium Sulfate (NH4)2SO4 o 24 % sulfur o Water soluble
