Husnain, H. Ishiga, T. Wakatsuki and T. Masunaga
The dynamics of a nutrient, as it moves from upland to lowland in a watershed, is important for enrichment of that nutrient in lowland agricultural fields and maintain its productivity (Hirose and Wakatsuki, 2002). In Indonesia, lowland areas are mostly occupied by sawah/wetland rice, and the productivity of rice is hence influenced by nutrient dynamics.
The trend of trace element ratio in soil along a watershed is one reliable method to study nutrient dynamics. The trace element and rare earth elements (REEs) has been used to track soil erosion and sediment movement (Bernard et al., 1998; Polyakov, 2002), study the weathering (Aide and Smith-Aide, 2003) and nutrient cycling in soisl and plants (Wyttenbach et al., 1998). Trace elements are widely used for provenance studies or as a tracer due to their relatively low mobility during sedimentation processes. According to Rollinson (1993), although the absolute content of some elements changes with weathering and leaching, the elemental composition of the clastic rock is still mainly controlled by the provenance area. Therefore, the ratios of some elements do not significantly change. This concept has been used as a basic theory of provenance study.
The question addressed in this research is whether the nutrient enrichment in lowland is derived from upper topographical position or come from other sources. This paper discusses the importance of the trace element behavior in studying the provenance of material accumulation in lowland sawah area that is responsible for the sustainability of rice production.
Keywords: Provenance, Trace element ratio, REE, Nutrient dynamics, sawah
Paper published inProceedings of the 10th International Conference of The East and Southeast Asia Federation of Soil Science Societies.