Polyacrylamide for Increasing Soil Moisture and Seeding Success.

The US Air Force trains with live munitions on a desert range west of Salt Lake City, Utah. They are committed to ecological restoration on lands damaged by resultant fire. However, revegetation is challenging due to low average annual rainfall of ~25 cm. Applications of subsurface polyacrylamide (PAM) were evaluated to determine the effects on establishment of Agropyron cristatum, Melilotus officinalis, Artemisia tridentata, Bassia prostrata, Linum lewisii, and Elymus elymoides under glasshouse conditions in a loam collected from the U.S. Air Force training grounds. Seeds were planted at the bottom of a furrow in 0.13 m² boxes with 0.04 m between top of the ridge and bottom of the furrow and 0, 20, or 40 g PAM band^-1, the equivalent to rates of 0, 1500, and 3000 kg PAM ha^-1, applied across a 0.43 m length at 0.08 m below soil surface in the furrow, with 0.03 m of soil below the band. Each species was planted separately in a row perpendicular to the furrow. The soil was initially watered once to saturation. Volumetric soil moisture in the furrow was 200 and 500% greater than the control for the 20 and 40 g PAM treatments, respectively, on day 21. Linum lewisii, Melilotus officinalis, Agropyron cristatum, and Bassia prostrata lived 10, 12, 13, and 23 days longer than the control for the 40 g treatment with less pronounced improvements seen at the 20 g rate. Application of PAM has promise for improving restoration success, although further studies are needed to evaluate PAM combinations with seeding rate reductions to avoid excessive competition.