Zeolite Soil Application Method Affects Inorganic Nitrogen, Moisture, and Corn Growth

Adoption of new management techniques which improve soil water storage and soil nitrogen plant availability yet limit nitrogen leaching may help improve environmental quality. A benchtop study was conducted to determine the influence of a single urea fertilizer rate (224 kilograms of Nitrogen per hectare) applied with band or fully-mixed zeolite (Clinoptilolite) application rates (up to 90 megagrams per hectare) on ammonium-nitrogen and nitrate-nitrogen concentrations in a Portneuf silt loam. Two additional greenhouse experiments were carried out to test the soil moisture status and corn growth in a Wolverine sand. Mixing urea fertilizer into silt loam soil resulted in greater urea mineralization, but the mixed zeolite was more effective at adsorbing and protecting ammonium-nitrogen against nitrification as compared to band application of fertilizer + zeolite. Increasing the rate of mixed zeolite into sandy soil increased the soil moisture content, and mixed zeolite soils contained 1.3% more soil moisture as compared to band zeolite applications. Following six weeks of corn growth in amended sandy soil, zeolite application at 22 megagrams per hectare appeared to increase corn weight compared to controls. However, increasing zeolite rate up to 90 megagrams per hectare caused a decrease in corn weight, likely due to the elevated zeolite Na content (3%). Fully mixing zeolite into soil reduces the rate of nitrification likely due to ammonium adsorption in the zeolite mineral lattice. Thus, mixing zeolite into soil may reduce the leaching of inorganic N. Mixing may also improve the soil water status, although initial leaching of zeolite-borne Na may be necessary before growing crops