ABSTRACT
A prototype N-fertilizer applicator was designed and constructed (U.S. Patents 5,797,459 and 5,913,368), to apply N-fertilizer to locally tilled soil, construct a hydraulic barrier (compacted soil) over the fertilizer, and form a surface dome or ridge. This localized compaction and doming (LCD) applicator was compared with a conventional knife applicator by investigating soil physical properties of the injection zone, nitrate redistribution during a growing season, com yield response, and leaching to subsurface drains. Data from these evaluations suggest that N applied by the LCD applicator is less susceptible to water percolation and leaching than N injected by a conventional knife injector. Soil nitrate concentrations were closer to the surface and less dilute when fertilizer was applied by the LCD versus the conventional knife. Subsurface drain water concentrations show that after 1 0 cm of drainage, 5% of knife injected chemicals were recovered, compared to just 1% of LCD applied chemicals. Modifying surface soils to alter water flow paths is a valuable tool to guard against groundwater or tile drain contamination by Nfertilizers.
