Relationship between ammonium fixation and some soil properties and effect of cation treatment on fixed ammonium release in a range of Trinidad soils

Abstract

The behavior of a diverse range of soils from Trinidad with respect to strongly fixed dynamics was studied. Fixed contents and additional ammonium fixation capacity (AAF) varied among the soils; the former increasing with clay content and ammonium fixation capacity (AFC) while the latter was related more to the soil's pH CEC and total carbon content Adsorption of ions into intercalary positions more than likely resulted in a reduction of the interlayer and increased the size of the individual clay particles thereby leading to an increase in the proportion of the coarse clay fraction after saturation for all soils. The release of this strongly fixed was significantly affected by the cation treatment and by the soil type. The River Estate soil showed the smallest release (9.56% of AFC), which probably was related to the dominance, in that soil of illitic minerals with a known high retentive potential for fixed Sodium treatment showed the greatest ability to release fixed followed by Ca²⁺ and then K⁺ resulting in the release of 18.6, 13.4, and 12.6% of the AFC, respectively.

Acknowledgments

The authors extend gratitude to the field technicians in the Soil Science Unit of the Department of Food Production and to the property owners for assistance and approval, respectively, in obtaining the samples of soils used in the investigations.