Carbon sequestration in agricultural soils is one way the industry could have an impact on carbon dioxide emmisions. No-tillage cropping has been shown to enhance carbon storage. The effect of conversion of long term tilled and no-tilled treatments is being evaluated in an experiment that began in 1981 and initially compared five tilled treatments to no-tillage. Since the mid 1980's the comparision has been between three tilled and three no-tilled soybean cropping systems. In the spring of 2002 each plot of the tilled and no-tilled treastments were spilt and one side of each plot was converted from tilled to no-tilled or vice versa. Prior to the conversion each side was sampled for soil carbon and nitrogen. Immediately after tillage they were sampled again. Yield differences have varied since conversion with a decline on the tilled area of the three no-tilled treatments in the third season asfter conversion. In the first seaason nematode levels also incresed about five-fold on the tilled side of the previous no-tilled plots. Carbon and nitrogen levels are have been evlauated each spring since conversion and will be reported.