EXTRACTABLE POTASSIUM AND SOLUBLE CALCIUM, MAGNESIUM, SODIUM, AND POTASSIUM IN 2 WHEY-TREATED CALCAREOUS SOILS

Cheese whey contains 1.0 to 1.4 g K kg(-1) and 5.0 to 10.0 g total sal ts kg(-1) (electrical conductivity [EC] of 7 to 15 dS m(-1)) and has a pH of 3.3 to 4.6. Much of the 38 x 10(9) L of whey produced in the US A each year is applied to soils. Whey application effect on the K and salinity status of irrigated calcareous soils has not been documented. Objectives of this study were to measure soil pH, sodium adsorption r atio (SAR), saturation paste extract (EC(e)), and extractable Ca, Mg, Na, and K changes due to whey application to irrigated calcareous soil s at different whey rates and different times of the year. Whey was ap plied to two calcareous Portneuf silt loam (coarse-silty, mixed, mesic , Durixerollic Calciorthids) soils and a calcareous Nibley silty clay loam (fine, mixes, mesic Aquic Argiustolls) soil at rates up to 2200 m (3) ha(-1). These treatments added up to 1050 kg Ca, 200 kg Mg, 790 kg Na, and 2200 kg K ha(-1) during winter-time, growing season, or year- round whey application. Soil bicarbonate-extractable K increased to mo re than 500 mg K kg(-1) in the surface 0.3 m at the highest whey rates and may induce grass tetany in livestock grazed on high whey-treated pastures. Soil K did not increase below 0.6 m in any treatment. Soil p H and SAR were not affected sufficiently to be of concern under these conditions. The EC(e) increased to nearly 2.0 dS m(-1) in the surface 0.3 m under the highest whey rates and would likely affect salt-sensit ive crop yields. After a 1-yr whey application rest period under irrig ated alfalfa (Medicago sativa L.), the EC(e) levels returned to backgr ound levels.