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

Adoption of new management techniques that improve soil water storage and soil N plant availability yet limit N leaching may help improve environmental quality. A benchtop study was conducted to determine the influence of a single urea fertilizer rate (224 kg N ha) applied with band or fully mixed zeolite (clinoptilolite) application rates (up to 90 Mg ha) on NH4-N and NO3-N concentrations in a Portneuf silt loam (coarse-silty, mixed, mesic, durinodic Xeric Haplocalcid). Two additional greenhouse experiments were carried out to test the soil moisture status and corn (Zea mays L.) growth in a Wolverine sand (mixed, frigid Xeric Torripsamment). Mixing urea fertilizer into silt loam soil resulted in greater urea mineralization as compared with band application of fertilizer + zeolite, and the mixed zeolite was more effective at sorbing and protecting NH4-N against nitrification. 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 with band zeolite applications. After 6 weeks of corn growth in amended sandy soil, zeolite application at 22 Mg ha seemed to increase corn weight compared with controls. However, increasing zeolite rate up to 90 Mg ha caused a decrease in corn weight, likely caused by the elevated zeolite Na content (3%). Fully mixing zeolite into soil reduced the rate of nitrification likely because of NH4 + 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.