AMMONIUM RETENTION IN SAND AMENDED WITH CLINOPTILOLITE.

Clinoptilolite zeolite has a rigid three-dimensional lattice with 10** minus **9 m sized tunnels, and an affinity for NH** plus //4 on its internal exchange sites. These internal tunnels are too small for 10** minus **6 m size microbes to access; hence, clinoptilolite has the potential to physically protect NH** plus //4 from nitrification by microbes, and may reduce volatilization losses. The objective of this study was to evaluate NH** plus //4 retention of sand amended with clinoptilolite. Retention of NH** plus //4 on clinoptilolite amended sands incubated at 20% volumetric water content, was studied in the laboratory. Clinoptilolite reduced NH** plus //4 losses from the soil mix and would allow increased plant N fertilizer-use efficiency. Thus clinoptilolite-amended sands have potential as a growth medium for turfgrasses on golf greens, where N use efficiency is typically low.