IMPROVING ROOT DEVELOPMENT WITH FOLIAR HUMIC ACID APPLICATIONS DURING KENTUCKY BLUEGRASS SOD ESTABLISHMENT ON SAND

Kentucky bluegrass (Poa pratensis) is a primary grass species used for athletic fields. A common problem faced by many athletic field managers is the need to achieve a functional playing surface soon after sodding. Humus, and its humic acid components, has been shown to improve rooting during establishment and management of mature turf in previous research. The objectives of this study were to examine the effects of two humic acid (HA) sources (peat and leonardite) on establishment rate of Kentucky bluegrass sod as determined by post-transplant root strength, root mass, tiller density, and visual quality. Sod was transplanted onto sand meeting United States Golf Association specifications. Treatments, arranged in four randomized complete blocks, included humic acid from peat (HAp; 47 g m^-2), humic acid from leonardite (HAl; 58 g m^-2), and a control. Treatments were foliar-applied every two weeks and nutrient availability was equalized with the use of a complete fertilizer solution. Two 12-week runs of the experiment were conducted: one from April through July and one from August through October. Both HAp and HAl treatments significantly increased root mass and root strength. On average, HAp and HAl treatments increased root mass 73% and 34%, respectively. The humic acid treatments, however, did not increase shoot tiller density or visual quality. The results suggest that frequent foliar applications of a small amount of humic acid may be an advantageous practice for improving the rate of Kentucky bluegrass post-transplant rooting.