Phosphorus (P) use in turfgrass has become more heavily scrutinized in recent years due to its suspected contribution to eutrophication of lakes and streams. P runoff occurs with sediment runoff which rarely occurs in turf. Many studies have shown turf to be an insignificant source of P runoff pollution. However, strict restrictions on P fertilizer use in turf are being enforced in more states in the U.S., permitting P application only when a soil test reveals the necessity for P input. P transformations between unavailable organic forms and plant available inorganic forms in the soil are not well-understood and are influenced by many environmental factors. Microsites within a soil lead to significant variations in P even over very short distances. This study has been designed to gather a better understanding of P dynamics in soil, specifically the relationship between temperature and plant available P when different nitrogen fertilizers are used. Field studies were established in April of 2006 on Kentucky bluegrass (Poa pratensis) at the Ohio Turfgrass Foundation Research and Education Center in Columbus, Ohio. Ammonium sulfate and calcium nitrate fertilizers will be applied at a rate of 1 lb per 1000 sq.ft. at four different dates throughout the season. Soil cores (depth 7.62 cm) will be taken bimonthly for two years and analyzed for plant available P using the Bray 1 test for phosphorus. We hypothesize that there will be an increase in plant available P in accordance with increasing temperatures and there will also be an increase in plots treated with nitrogen fertilizers.