Correlation between Available Soil Arsenic, Estimated by Six Methods, and Response of Corn (Zea mays L.)

The results of six methods of estimating available As on 28 different soils from eight states in the United States were correlated with the wet tissue weight of 4‐week‐old corn ( Zea mays L.) grown on these soils. Linear correlation coefficients between plant weight and the log of the soil As concentration were determined by the following techniques ( i ) total As; ( ii ) summation of “Easily‐Soluble‐,” Fe‐, Al‐, and Ca‐arsenate fractions; ( iii ) summation of “Easily‐Soluble‐,” Fe‐, Al‐, and Ca‐arsenate fractions modified by their individual phytotoxicity; ( iv ) 0.05 N HCl and 0.025 N H 2 SO 4 mixed‐acid‐extractable As; ( v ) 0.5 N NaHCO 3 ‐extractable As; and ( vi ) selection of the As extracted by 0.05 N HCl and 0.025 N H 2 SO 4 or 0.5 N NaHCO 3 methods, depending on soil pH. The last four techniques were equally effective in predicting plant response ( r = 0.81 to 0.82) to soil arsenic. The mixed‐acid or bicarbonate methods were preferred because they require less labor.