Soil fertility and pest management are the most critical management challenges faced by organic vegetable growers. Cover crops used as green manure can help prevent erosion on fallow land, add nitrogen to the soil, increase soil organic matter, and suppress weeds. An on-farm participatory experiment was established on a five acre organic community supported agriculture (CSA) farm in Madison, WI, to compare two types of green manures and three inexpensive organic soil amendments on subsequent vegetable yield, weed populations and soil factors. First year treatments in 2003 and 2004, consisted of replicated green manures strips of either sorghum sudangrass (Sorghum bicolor) or red clover (Trifolium pretense) mixed with oats (Avena sativa). In the fall replicated strips of compost, leaves supplemented with alfalfa meal, woodchips supplemented with alfalfa meal and an untreated check were spread perpendicular to green manure strips. Tomatoes, carrots and squash were grown in the subsequent year in a Latin square design and data was collected on yield, weed populations, and soil factors. Data was analyzed using ANOVA. There was not a significant difference between treatments on vegetable yield (p>0.05). Strips of sudangrass decreased the prevalence of quackgrass (Agropyron repens) shoots compared to red clover strips (p<0.01), but there was not a significant difference between the two cover crops in the density of broadleaved weeds (p>0.05). Data from the 2005 will include vegetable yield, weed population density and soil nitrate tests.