Extractable potassium and soluble calcium, magnesium, sodium, and potassium in two whey-treated calcareous soils

Cheese whey contains 1.0 to 1.4 g K kg-1 and 5.0 to 10.0 g total salts 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 × 109 L of whey produced in the USA 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 ratio (SAR), saturation paste extract (ECe), and extractable Ca, Mg, Na, and K changes due to whey application to irrigated calcareous soils at different whey rates and different times of the year. Whey was applied 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 m3 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 more 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 pH and SAR were not affected sufficiently to be of concern under these conditions. The EC, increased to nearly 2.0 dS m-1 in the surface 0.3 m under the highest whey rates and would likely affect salt-sensitive crop yields. After a 1-yr whey application rest period under irrigated alfalfa (Medicago sativa L.), the ECe levels returned to background levels.