Estimation of nitrate retention in a Ferralsol by a transient‐flow method

Abstract

Summary Anion retention is important in highly weathered soils that contain large amounts of iron and aluminium oxides with surfaces of variable charge. Sorption mechanisms retard anionic solute transfer through these soils. We determined the retardation factor for nitrate in highly weathered Ferralsols from New Caledonia from dynamic experiments using a transient‐flow method, and we evaluated the effect of soil solution concentration and organic matter content. A simple method with sectionable tubes was used to determine the nitrate isotherm during non‐steady‐state water flow under unsaturated conditions. The topsoil retarded the movement of nitrate, and the sorption followed a linear isotherm. In subsoils, retardation factors were larger and increased from 1.15 to 2.05 at soil pH as the NO3–‐N concentration of the input solution decreased from 71.43 to 0.35 mm, indicative of a non‐linear isotherm. Positive surface charge sites were considered to be of two types: one with strong affinity for nitrate at small concentrations and one with weak affinity for adsorption of nitrate at larger concentrations. This type of isotherm with high‐ and low‐energy sites is similar to those found for oxyanions and heavy metals. The related anion exchange capacity was larger than that usually observed in soils of variable charge. Not all exchange sites were detected with our method, and some sites were obviously not available for nitrate retention.

Biogeochemical cycles of nutrients in tropical Eucalyptus plantations

“…This feature was a result of various factors: (i) the fast development of tree crowns leading to large nutrient requirements and large amounts of water taken up by trees, from age 6 months onwards (Figs. 2 and 4); (ii) various degrees of ion adsorption on the soil solid phase (oxides, OM and clay minerals) leading to slow transfer of ions in deep soil layers (Duwig et al, 2003;Maquè re, 2008); (iii) very rapid development of fine roots in deep soil layers making it possible to take up nutrients before they were lost by deep drainage Jourdan et al, Fig. 5.…”

Nitrate adsorption in some andisols developed under different moisture conditions

“…Ion-exchange reactions delay the ion movement in soils (Ishiguro et al 1992). In terms of anion retardation, subsoils will usually be more effective because they are likely to exhibit a higher anion-exchange capacity (AEC) than topsoils, with the organic matter content promoting the cation-exchange capacity (Bellini et al 1996;Warren and Kihanda 2001;Duwig et al 2003). This AEC enables to retard nitrate movement and to mitigate groundwater contamination (Wong et al 1990;Reynolds-Vargas et al 1994; Bellini I E-mail: masatani@obihiro.ac.jp.…”

“…Many studies have been conducted to evaluate the surface-charge properties and nitrate retention of soils in tropical and subtropical regions with a high degree of weathering and that are rich in iron oxides and kaolinite (Kinjo and Pratt 1971;Mekaru and Uehara 1972;Ng Kee Kwong and Deville 1984;Bellini et al 1996;Toner et al 1989;Cahn et al 1992;Eick et al 1999;Warren and Kihanda 2001;Duwig et al 2003). Allophanic Andisols, which are derived from volcanic ash and developed under humid and temperate conditions, have both positive and negative variable charges that depend on solution pH and ionic strength (Wada 1989).…”

Numerical Simulation of Fertilizers Movement in Sand and Controlling Transport Process via Vertical Barriers

“…and R. Zhang, 2000; Abdel-Nasser, 2001; Duwing, C., T. Becquer, L. Charlet and B.E. Clothier, 2003) [14], [15]. These models have a varied degree of abstraction concerning the simulation of complex physical and biochemical soil processes and for that reason it is not easy to choose a suitable model to estimate the impact of agriculture on groundwater pollution.…”