THE RELATIONSHIP BETWEEN FLUORIDE-TITRATIBLE (REACTIVE) SOIL ALUMINUM AND PLANT GROWTH

Abstract

The status of phytotoxic Al in soil was determined by means of titrating reactive soil Al with fluoride using fluoride-ion-selective electrode. fluoride-titratible Al was compared with 1 N KCl exchangeable Al in soil samples from Brazil and kaolin clay with and without added Al. Monon wheat plants were grown in soils with different levels of reactive Al as characterized by fluoride titration. Plant yield, as determined by dry weight, decreased significantly with increasing quantities of fluoride-titratible Al. The fluoride-titratible Al was more closely correlated with plant growth than was KCl-extractable Al, and the titration procedure has potential for defining the nature and type of phytotoxic Al in soil.