SOIL FERTILITY CONSTRAINTS FOR RICE CULTIVATION IN THE MEKONG DELTA, VIETNAM(International symposium on volcanic ash soils and field workshop in the Mt. Fuji area)

  • Minh Vo Quang
    Department of Soil Science and Land Management, College of Agricultural and Applied Biology, Cantho University

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In the Mekong delta, areas of intensive rice production have been rapidly enlarged. Soil fertility degradation in this system can be one of the most important factors contributing to the yield decline. Information on soil fertility and recommendations on improving soil constraints will provide basic data for proper soil management, land evaluation and land use planning. A Fertility Capability Classification (FCC) system, based on the work of Sanchez (2003), incorporates characteristics of soil morphology, soil physics, and soil chemistry. Most of the class limits are borrowed from Soil taxonomy (Soil Survey Staff, 1994) or the FAO/Unesco soil classification system (FAO, 1974). Data from 300 soil profiles and 28 field experiments were collected from field surveys and other sources to develop and validate the FCC system. The FCC system developed for classifying intensive rice production in the Mekong delta, consists of three new categories : -Category 1 : Topsoil depth (0-20cm) ; substrata topsoil depth (20-50cm), and subsoil depth (50-100cm). -Category 2 : Soil texture : Clay (C) ; Loam (L) for topsoil (0-20cm); clay (C) and loam (L) for substrata topsoil (20-50cm), and clay (C), loam (L), and sand (S) for subsoil (50-100cm). Category 3 : Fourteen modifiers that effect rice growth were determined : a, a^-, c, c^-, e, f, f^- , g^+, i, n^-, s, s^-, o, and p. Among these parameters, a, a^-, e, g^+, i, k, n^-, o, p, s^- apply to the topsoil, a, a^-, c, f, g^+, k, i, s, s^-, n^-, apply to the substrata topsoil, and c^-, f, s, s^- apply to the subsoil. There were 6 modifiers added to the system : p, o, c, c, f, f.The structure of soil name in the system needs to be changed as follows : topsoil layer depth (1) plus soil texture of topsoil layer (C, L) plus modifiers of topsoil layer (a, a^-, e, g+, i, k, n^-, o, p, s^-) plus Substrata topsoil depth (2) plus soil texture of substrata topsoil (C, L) plus modifiers of substrata topsoil (a, a^-, c, f, g^+, k, i, s, s^-, n^-) plus subsoil depth (3) plus soil texture of subsoil (C, L, S) plus modifiers of subsoil layer (c, f, s, s^-). Our results showed that there is a relationship between modifiers of the FCC system with the soil diagnostic horizons, properties and materials of the soil World Reference Based (WRB) map. This relationship was determined as follows : a, a- with Sulfuric horizon, Alic, and Thionic properties, modifier c with Sulfuric horizon, Thionic property, and Sulfidic material, modifiers g, g^+ with Gleyic, Stagnic properties, modifiers i, i^- with Plinthic horizon, and Rhodic properties, but modifier i^+ has an additional relationship with Gleyic property. Modifier n^- related to Hyposodic property, modifier s^- with Hyposalic property and modifier v with Vertic horizon. Specially, modifier k has a relationship with Sandy texture. The major soil constraints in the intensive rice cultivation areas can be listed as follows : low organic carbon content (o) ; high P fixation and high Fe toxicity potential (i) ; potential salinity (s^-) ; low available P (p) ; high acidity and Al toxicity (a) ; the separation of actual acid sulfate soils (c, c^-) and potential acid sulfate soils (f, f^-). The new FCC system, and FCCMD software developed can be applied to the soil fertility evaluation of paddy soils in the Mekong delta. However, as in the 3^<rd> FCC (Sanchez et al, 2003), this evaluation is considered "open ended" ; if a soil cannot be adequately classified, then it is possible to create a new phase or modifier. It needs to accommodate more modifications in the future for better evaluation and management.

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詳細情報 詳細情報について

  • CRID
    1571135652283879552
  • NII論文ID
    110006390923
  • NII書誌ID
    AN00239079
  • ISSN
    04656083
  • 本文言語コード
    en
  • データソース種別
    • CiNii Articles

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