Rainfall simulations were conducted on a Class B biosolids application field located in Northwestern Harris County, Texas to evaluate the applicability of the P Index (PI) on these application sites. This was done using small plot rainfall simulations to determine chemical characteristics of runoff water and soil samples. The soil on site was Hockley fine sandy loam, 1 to 4% slopes, fine-loamy, siliceous, semiactive, hyperthermic, Plinthic Paleudalfs. The concentration of dissolved P in the runoff samples from three rainfall events on three plots ranged from 2.1 mg/L to 0.9 mg/L. The amount of dissolved P that the site would contribute to the watershed was calculated to be 0.164kg/ha for a 7.5 cm rainfall event. Although the contribution of dissolved P was low, the concentration of P in the runoff was high. Nitrate concentrations in the runoff decreased from an average of 2.75 mg/L across three plots for the first rainfall event to an average of 0.48 mg/L across three plots for the third event. Soils were analyzed at 0-5, 5-15, and 0-15 cm of depth. The samples were extracted by both Mehlich III and TAMU methods and analyzed for P, Ca, Mg, K, Na, and S. The P concentration at 0-15 cm averaged 301 mg/kg and 1780 mg/kg for Mehlich III and TAMU extracts respectively. The analyses showed a strong disparity between the concentrations of Ca and Mg. The Mehlich III ratio of the soil concentration of Ca to Mg was 89:1 and should be closer to 7:1 for exchangeable Ca:Mg. The high ratio may induce Mg deficiency. There may also be a need to add extra K because high levels of Ca from liming materials can impair K uptake. The K:Mg ratio is 1:1, the same as reported ratios. High Ca concentrations may also result in K deficiencies.