Declining soil fertility is one of the main causes for decreased yields in mature alfalfa stands. Nitrogen, phosphorous, and sulphur are three nutrients that are often found to be limiting in prairie soils. In this study we applied nitrogen, sulphur, and phosphorous fertilizers as well as Sinorhizobium meliloti and Penicilium bilaiae inoculants to mature alfalfa stands to determine how these different treatments affected biomass yield and nutrient content. The experimental plots were established in the spring of 2004 and yield data from this season is presented. In season 2 (2005) we will be monitoring the experimental plots for residual responses from the treatments.