Influence of Copper or Cadmium on Soil Potassium Availability Properties

Abstract

AbstractThe objective of this research was to determine the nature and extent of increased soil levels of Cu or Cd on K availability properties. Bozeman silty clay (Typic Argiborolls) samples were equilibrated at soil water potentials of −33 or −100 KPa, at temperatures of 5 or 20 °C for 3 or 14 d after additions of three levels of K and three levels of Cu or Cd. Soil solution was extracted by an immiscible liquid displacement technique. The activity of Ca, Mg, and K in soil solutions were increased by Cu or Cd additions (aCa > aMg > aK). The ratio of K to Ca + Mg (K intensity) was decreased by Cu or Cd additions when no K was applied, but increased at high levels of K addition. Soil temperature and water potential interacted with Cu or Cd additions to alter cation activities. Soil K buffer capacity was decreased by Cu or Cd additions. Increasing addition of K increased the proportion of K in both exchange and solution phases, at the expense of both Ca and Mg. Increasing additions of Cu or Cd decreased the fractional saturation of K and Mg, but increased that of Ca in the solution phase, with the reverse influence being exhibited on the exchange phase. Results indicate that Cu had a stronger influence than Cd (at equal rates of addition) on soil properties which regulate K availability.