BORON TESTS AND DETERMINATION FOR SOILS AND PLANTS

Abstract

The quinalizarin color reaction for the detn. of B in various materials is giving satisfactory results and has come into general use. Improvements made in the procedure since the first report on the method include the use of a combination quinalizarin-H2SO4 soln. and special equipment for storing and dispensing this reagent. The color reaction is virtually instantaneous, and readings can be made as soon as the test color soln. has been cooled to room temp. Use of a photoelectric colorimeter is satisfactory when proper precautions are taken in the selection and care of colorimeter tubes for holding the test soln. Visual readings by means of comparator tubes give equally satisfactory results. Detailed directions are given for the application of the quinalizarin reaction to the detn. of the available B of soils extracted with boiling water, total B of soils brought into soln. after fusion with Na2CO3, and total B of plant materials after ashing and extraction with dilute acid. The quinalizarin procedure was compared with the curcumin procedure; both gave equally satisfactory results. The former is less laborious and more expeditious; the latter has the advantage of using reagents that are more easily prepd. and handled.