ACID SOIL INFERTILITY AS RELATED TO SOIL-SOLUTION AND SOLID-PHASE EFFECTS

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Abstract
Lettuce and barley plants were grown in a column of pots with a soil soln. circulating through soil mixed with sand, and through sand alone. In the acid soil columns, plants grew poorly both in the sand pot and in the one containing soil + sand. Where the soil had been limed, plants grew equally well in the 2 phases. Barley plants were grown in acid soil suspensions and in solns. at equilibrium with each other across a collodion membrane. Similar plants were grown in limed acid soil suspensions and in solns. at equilibrium with each other across a collodion membrane. The plants grew equally poorly on both sides of the unlimed set and equally well in the limed set. Barley plants were grown in soil solns. displaced from an acid soil. Shoot growth and more especially root growth were inhibited in the unaltered soil soln. having a pH of 4.2. Adding Ca(OH)2, NaOH, or KOH to raise the pH to 5.8 resulted in normal plant growth. Barley plants were grown in soil solutions displaced from a limed acid soil. Shoot and root growth were good in the unaltered soil soln. having a pH of 58. Reducing the pH to 4.2 by addition of H2SO4 caused a slight decrease in yield. Addition of Al in the amt. found in the acid soln., and of H2SO4 to bring the pH to 4.2 produced very poor plants similar to the ones grown in the unaltered acid soil soln. Addition of Mn produced brown spots on the leaves but no appreciable change in dry wt. Similar effects were produced in water cultures based on analyses of solns. displaced from acid soils.