AN EVALUATION OF ANION-EXCHANGE RESIN USED TO MEASURE NITRATE MOVEMENT THROUGH SOIL

The attribute that ion-exchange resins remove ions from solutions movi ng through them can be used to measure nitrate transport through soils . The characteristics of nitrate adsorption by resins must be known to interpret nitrate accumulation on ion-exchange resins embedded in soi l. The extent to which anion exchange resins retain NO3- from soil lea chate was measured in 15.9 cm diam.by 60 cm long intact cores of Nolin (fine silty mixed mesic Dystric Fluventic Eutrochroept) soil. A NO3-- selective resin and a non-selective resin were tested. Columns were fe rtilized at a rate of 300 kg N/ha and 150 kg Br-/ha and leached with 5 0 cm of water. Under these conditions, both resins retained approximat ely 80% of the NO3- and Br- leached through the soil. This compared wi th greater than 95% retention in laboratory columns containing only re sin. The difference in retention was attributed to different flow thro ugh the resin associated with the method of resin emplacement.