The effects of two composts on soil physical properties and nitrogen (N) availability to corn were investigated in two field experiments and a laboratory study. Three annual applications of compost, each 50 Mg ha -1, decreased soil bulk density and particle density, and increased water content. Organic carbon in the soil was enhanced by 35-58% of that added in compost, but 77-100% of N in the compost was still present in the Ap horizon after the third application. Scott's compost had little effect on N uptake into grain over three seasons, while 1.2-2.8% of N applied in Loam Crafter's appeared to be incorporated into grain. Between 1.7-9.8% of N in the compost was mineralized over 21 weeks in the laboratory, suggesting that about 30% of compost N mineralized in the field entered the grain. Compost applications up to 400 Mg ha-1 yr -1 did not increase the potential for nitrate leaching.