Release of Fixed Ammonium from Soil by Ball Milling

Abstract

RECENT research has shown that some soils have the ability to fix appreciable quantities of ammonium in a form not readily exchangeable with l N potassium chloride or available to plants and micro-organisms. Fixation results from a replacement by ammonium for interlayer cations (calcium, magnesium, sodium, hydrogen) in the expanded lattice of clay minerals. Since many soils contain the types of clay minerals known to fix ammonium, it may be deduced that they will contain fixed ammonium through the reaction of minerals with ammonium produced naturally. This deduction is supported by recent reports^1–4 that some soils contain considerable amounts of naturally occurring fixed ammonium. However, these findings require confirmation, since the methods employed cannot be considered entirely satisfactory.