Woody biomass is a crop that might be profitably produced on marginal lands in Iowa. However, there is little available information regarding the growth and economic feasibility of woody biomass in Iowa. To address this issue, a study was initiated in 1995 to analyze biomass growth of certain species planted on marginal lands. Nine species/hybrids including: the 'Crandon' clone (Populus alba X P. grandidentata), 'Eugenii' clone (Populus euramericana), and silver maple (Acer saccharinum) were established in test plantings on bottomland, steep slopes, and upland agricultural land. Annual growth data were collected for each test planting over a ten-year period. Yield models were developed to predict biomass per hectare for the three named species/hybrids, using two modeling strategies. The first was a site specific model, meaning that separate equations were developed for each tree species on each land type. The second was a site quality specific model, meaning that separate equations were developed for each tree species, using the average height of trees at age eight as a measure of site quality. Crandon had the highest rate of biomass production on all land types. Economic analyses were conducted to compare the feasibility of growing the three tree species on various land types in Iowa, and Crandon had the highest economic return for short rotation biomass production on all land types.