Fig. 13. A sensitivity analysis of the estimated relative agronomic effectiveness (RAE) as calculated by the phosphate rock decision support system (PRDSS). Factors affecting RAE include phosphate rock solubility measured by a second extraction using neutral ammonium citrate (NAC2), soil pH, organic C (%), sand (%), P fixation (%), Al saturation (%), and rainfall (mm). Values in brackets are the range of values for each factor in the PRDSS.