Nitrogen mineralization in tropical wetland rice soils, 2: Application of exponential models
1996
Watanabe, I. (Mie Univ., Tsu (Japan). Faculty of Bioresources) | Manguiat, I.J. | Mascarina, G.B.
Soil N mineralization during flooded incubation at 25 and 30 degrees C in 30 tropical wetland rice soils from the Philippines, Indonesia, Malaysia, and Thailand, reported earlier, were analyzed by applying first-order kinetic (exponential) equations. The slowdown in N mineralization rate in the latter period of incubation was observed in one third of cases at 25 degrees C, and in two thirds of cases at 30 degrees C. Alternatively, exponential equations were applied for mineralization potentials independently of temperature. In 17 cases, single term equation gave the best fit, ant in 13 cases, the two-term exponential equation gave the best fit. The second term expressed net initial immobilization fraction except for one soil. Single term equation gave a better fit when the soil clay content was less than 30% and sand content more than 20%, and the kinetic constants were negatively correlated with the clay content. Average ratio of k1 at 30 to that at 25c was 1.7 in the single term equation, and 1.4 in the two-term equation. Comparison of these data with the reported data from Japanese soils was presented
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