Automatic apparatus for the determination of pH and nitrate in soils

Abstract

An apparatus is described that automatically extracts and analyses batches of up to 60 soil samples. Analysis is performed electrochemically by means of either a pH or ion-selective and reference electrodes. The electrode output is amplified and recorded on a chart recorder, thereby allowing the electrode performance to be monitored. Results of tests with both pH and nitrate ion-selective electrodes are reported. Good agreement was obtained between automatic and manual methods. Difficulty was experienced with the operation of an Orion nitrate electrode but tests using a Corning electrode on the apparatus gave excellent recoveries and reproducibility.