|Dontsova, K - PURDUE UNIVERSITY|
Submitted to: Soil Science Society of America Annual Meeting
Publication Type: Proceedings
Publication Acceptance Date: September 15, 2002
Publication Date: November 2, 2002
Citation: DONTSOVA, K., NORTON, L.D. ATR-FTIR STUDY OF AMMONIA SORPTION BY SOIL AND SPECIMEN CLAYS. CD-ROM. INDIANAPOLIS, IN: SOIL SCIENCE SOCIETY OF AMERICA ANNUAL MEETING. 2002. Technical Abstract: Soil clays are known to enhance ammonia retention when anhydrous ammonia fertilizer is injected into the soil. In this study, ammonia absorption by SAZ-1 smectite and the clay fraction of Blount soil (fine, illitic, mesic Aeric Epiaqualfs) was observed in situ using (define) ATR cell. FTIR was used to identify the species of ammonia present on the clay surface. Clays saturated with Ca or Mg were deposited onto the ATR cell, dried, equilibrated at high or low partial pressure of water vapor, and exposed to NH3 gas. It was observed that immediately after exposure of clay sample to ammonia, the FTIR spectra indicated a presence of ammonia in a protonated form as NH4+ and in unprotonated form as physically absorbed NH3. After ammonia gas was removed from the ATR cell by flowing air, the peak belonging to physically absorbed ammonia soon decreased in intensity and disappeared, while ammonium was retained. The total amount and form in which ammonia was adsorbed was affected by clay mineralogy, water content and the exchangeable cation. At high clay water contents more ammonium was adsorbed on Mg-clays than on Ca-clays. In SAZ clay, more ammonia was protonated to ammonium at a low partial pressure of water vapor. The impact of this research is improved management of nitrogen and protection of ground water quality.