Fig. 3. Comparisons of iron-oxide impregnated paper–extractable phosphorus in runoff water (FeO-P_w) in reverse osmosis water (RO) and a 50:50 mix of RO water and tap water (RO/Tap) versus Olsen P (P_i), water-soluble P (P_ws), and iron-oxide impregnated paper–extractable P (FeO-P_s) soil tests. Regressions do not differ among RO and RO/Tap waters, except intercepts differ between RO and RO/Tap runoff waters for P_i. All regressions are significant (P 0.05).