Behavior and availability of ammonium in flooded soils /
Mongkorn Somsud.
- Los Baņos, Laguna : Cavite State University- Main Campus, 1980.
- 80 pages : illustrations ; 28 cm.
Thesis (Ph.D. - - Soil Science) University of the Philippines, College, Laguna.
Includes bibliographical references.
SOMSUD, MONGKORN, University of the Philippines at Los Banos, June, 1980. Behavior and Availability of Ammonium in / Flooded Soils. Major Professor: Dr. Santiago N. Tilo
The studies were conducted to find out the native fixed-Ni;, the extent and magnitude of ammonium fixation of some Philippine and Thai soils, ammonium volatilization, availability of native fixed-NHy and recovery of applied ammonium in the presence of a growing lowland rice.
The values of native fixed-Buy varied from 5 to 200 ppm of nitrogen, there appeared to have no definite trend in the distri of fixed-NH, with soil depths, The amounts of native fixed-NH, were related to the Orders of soil. The amounts of fixation of applied ammonium ranged from 3 to 108 ppm of nitrogen. Oven- drying tended to fix more applied ammonium than air-drying treatment.
The average ammonia volatilization ranged from 1.79% to 11.06% and 0.13% to 1.97% of applied ammonium without and with rice plant, respectively. The volatilization was related to the amounts of exchangeable Ca, initial soil pH, and a standing rice crop caused to decrease the volatilization.
Volatilization rate was rapid at first, then it slowed down during the second week. Fixation of applied ammonium at different periods of submergence varied from 0.42% to 85.83% and 10 to 17% of applied ammonium without and with a crop, respectively. The fixation decreased with time of submergence. The availability of native fixed-NH, ranged from 2 to 8% and from 5 to 26% without and with rice crop, respectively. Recovery of applied ammonium by the rice plant ranged from 0.7 to 4.2%. The percentages were quite low owing to the immaturity of the plants.