Assessing Impacts of Cheese Whey Wastewater on Vegetation.

Cheese whey wastewater (CWW) is often disposed by land application in the Southeast, which has the potential to runoff and stimulate eutrophication due to its high carbon loading and nutrient content. When land application is prohibited due to high runoff potentials, CWW is stored, which causes changes to CWW properties. CWW has the potential to benefit and harm vegetation it contacts. The objective of this study was to (1) evaluate the effect of fresh and stored CWW with three application frequencies on foliage health and biomass and (2) evaluate the tolerance of five forage species to CWW application. Three greenhouse experiments were conducted. The first compared fresh and stored CWW (pH 5.8 and 3.4, respectively) applied to ryegrass var. King (Lolium multiflorum) twice daily (D), twice per day on alternating days (A), and twice per day weekly (W). The second experiment was similar in design, but used a new collection of CWW (fresh CWW pH 4.5 and stored CWW pH 6.5) and included fresh CWW artificially adjusted to pH 6.5 applied D, A, and W. The third experiment compared five forage species: ryegrass, sorghum sudangrass var. Sugar Graze II hybrid (Sorghum bicolor x Sorghum bicolor var. sudanense), cereal rye var. Wrens Abruzzi (Secale cereale), bermudagrass (Cynodon dactylon), and tall fescue var. KY 31 tall (Festuca arundinacea). Results indicated that CWW less than pH 4.5 was harmful to plant foliage and was lethal when applied D and A. When the pH of CWW was above pH 4.5, damage to plant tissue was minimal. Fresh CWW increased biomass of all species, except sorghum sudangrass. Stored CWW did not result in increased biomass. Cool season grasses, especially tall fescue, were most tolerant to CWW. Bermudagrass was moderately tolerant of CWW, but would likely benefit from reduced frequency of application.