Studies were conducted to determine why certain soil test methods fail to indicate the actual lime requirement in many Ohio soils. Samples of 14 soils from various areas of the State were collected for study. The soils were incubated with various rates of applied CaCO3 to determine actual lime requirement of each soil. Attempts were made to find laboratory methods that would accurately indicate the lime requirement of each. For these soils the Woodruff method had indicated only about half the amount of the actual lime requirement. The Mehlich triethanolamine method indicated accurately the amount of lime required for the unlimed acid soils. However, this method indicated too high a lime requirement on soils partially limed. Subtraction of the acidity measured above pH 6.8 by the triethanolamine method and then addition of the extractable Al, gave a very good indication of lime needs on all soils not limed above neutrality regardless of lime additions. Addition of extractable Al to total bases and triethanolamine‐measured acidity to pH 6.8 gave nearly constant cation‐exchange capacities of soils regardless of lime additions. These studies have led to development of an improved soil test buffer method for rapid routine laboratory analyses. It appears to be adequate for indicating lime needs of soils regardless of extractable (soluble) Al present.
A greenhouse experiment was carried out with 16 columns of an undisturbed Oxisol that had sufficient subsoil acidity to restrict root growth of a wide variety of crop plants. The objective was to determine the effects of surface applied CaCO3, CaSO4·2H2O, and water on subsoil pH and exchangeable Al, Ca, and Mg. Eight soil columns were treated with CaCO3 or CaSO4·2H2O at rates equal to 0.25 and 1.50 × the lime equivalent (KCl‐extractable Al). The irrigation treatments consisted of trickle irrigation applied at 8.94 and 17.88 mm day−1 for 6 months. These treatments were superimposed on the amendment treatments. Observations included volume and composition of drainage water during the course of the experiment and chemical composition of the soil column by depth increments once the irrigation treatments were completed. Soil analysis included pH, cation exchange capacity (CEC), exchangeable cations, and composition of saturation extracts of soil. Effects of CaCO3 treatments were observed only in the upper 20 cm of the profiles irrespective of irrigation and fertilizer treatments. The CaCO3 treatments increased soil pH, CEC, and exchangeable Ca while decreasing exchangeable Mg and exchangeable Al; and CaSO4·2H2O treatments reduced the level of exchangeable Al and Mg throughout the 100‐cm depth profiles while increasing the level of exchangeable Ca. Soil pH and CEC were unaffected by the latter treatment. Based on the effectiveness of CaSO4·2H2O in reducing exchangeable Al and Mg while increasing exchangeable Ca, the combination of dolomitic lime and gypsum appears to be an appropriate amendment treatment for Oxisols with toxic concentrations of available Al.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.