Abstract: A four-replicate turfgrass trial was established in May 2002 to evaluate the effect of organic soil amendments on turf growth. The amendments included peat moss and four commercial composts (compost A was cattle manure-based, compost B was swine, poultry and cattle manure-based, compost C was biosoild-based, and compost D was poultry manure-based). The amendments were pre-mixed at several ratios (1:5, 1:4, 1:3, 1:2, and 1:1 amendment: soil), then applied onto the test plots. Control plots of topsoil and subsoil were included for comparison. The relative growth of the plots was measured by three clipping harvests. Combined clipping yield averages for amendments applied at 1:4 and 1:1 ratios showed significant differences among treatment types and when comparing treatments to controls. Average clipping yields of plots with 1:1 treatment to subsoil ratios ranged from 7364 to 3317 g/100m² where compost C > subsoil control > topsoil control > compost B > peat moss > compost A > compost D. The average yields for the 1:4 treatment to subsoil ratio plots ranged from 7377 to 3200 g/100m² where compost A > compost C > subsoil control > topsoil control > compost D > peat moss > compost B. No other significant differences in average clipping yields were observed. Soil moisture measurements were taken regularly and soil bulk density values were calculated. Preliminary observations demonstrate a wide variability in performance of organic soil amendments and their impact on turf growth. It is expected that positive treatment effects will become more apparent in the 2003 growing season when supplemental moisture and fertilizer is restricted.