|Wu, Jigang - IOWA STATE UNIVERSITY|
|Barak, Philip - UNIV OF WISCONSIN MADISON|
Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 31, 1997
Publication Date: N/A
Technical Abstract: We investigated the influence of timing and placement of NH4+ and K+ fertilizer on the leaching of NO3- from soils. Treatments included control (Cont), N only (N-only) N before K (N/K), K before N (K/N), and N and K applied simultaneously (N+K). Fertilizer solutions were applied on two consecutive days by injecting 5 mL of 1.26 M NH4Cl, 0.45 M KCl, and/or H20 2 cm below the surface in the center of each of 15 soil columns (7.7 cm diameter by 20 cm long). The columns were leached every two weeks with 200 mL of 0.001 M CaCl2, and the leachate was analyzed for NO3- and NH4+. During the latter part of the experiment (days 68 through 180) NO3- leaching for the N/K treatment was significantly different than that for the N-only treatment; and by day 180, 10% less NO3- had leached from columns receiving both NH4+ and K+ fertilizer (regardless of timing) relative to the N-only columns. The results suggest that placement of K+ in the same soil volume as NH4+ enhances NH4+ fixation and thereby reduces NO3- leaching.