The Basic Cation Saturation Ratio Concept and Lime and Potassium Recommendations on Delaware's Coastal Plain Soils
1981
Liebhardt, William C.
A lime-potassium factorial experiment (four K and seven lime treatments) was established on a Coastal Plain soil in 1970. Wide ranges in soil pH and percent Ca, Mg, and K saturation were obtained. Results indicate that the use of the Basic Cation Saturation Ratio Concept for making fertilizer recommendations should be modified for Delaware's sandy Coastal Plain soils. This concept, used by commercial labs, recommends that the exchange complex contain 75% Ca, 15% Mg, and 2–5% K. Research shows that use of these saturation percentages and the resulting Ca/Mg, Ca/K, and Mg/K ratios is not warranted and may result in reduced yields or increased costs, or both. A liming program which maintains the soil pH between 5.5 and 6.0 is suggested. Soil pH > 6.0 tends to result in Mn deficiency. To maintain a soil pH between 5.5 and 6.0 requires a Ca plus Mg saturation of 65–75% rather than that presently suggested by commercial labs (85–90%). Calcium plus magnesium saturation of this magnitude results in a soil pH of 6.5–6.8 on these sandy soils and a resulting Mn deficiency. Wide ranges or ratios of Ca and Mg have not influenced yield as long as soil pH is in the correct range. A K saturation of 2–5% is suggested by the use of this concept, data indicates that this saturation percentage is sufficient for corn and soybeans on Delaware's sandy Coastal Plain soils.
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