Surface water management under varying drainage conditions for rice on an acid sulphate soil in the Mekong Delta, Vietnam

Hanhart, K.; Ni, Duong Van; Bakker, N.; Bil, F.; Postma, I.; Mensvoort, M.E.F. van

doi:10.1016/s0378-3774(96)01298-x

Cited by 18 publications

(17 citation statements)

References 4 publications

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“…2000). In the dry season, water table depletion results in strong acid soil reactions as a result of oxidation of reduced sulfur compounds (Hanhart et al . 1997; Tipping et al .…”

Section: Introductionmentioning

confidence: 99%

Effects of drying on the release of solutes from acid sulfate soils distributed in the Mekong Delta, Vietnam

Kawahigashi¹,

Minh²,

Nguyen³

et al. 2008

Soil Science and Plant Nutrition

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Acids and soluble metal loads resulting from strong acidification preceded by severe drying of acid sulfate soils are fatal soil conditions for agricultural productivity and aquaculture environments. A greater concentration of dissolved Al and Fe after seasonal drought was confirmed in our previous paper using acid sulfate soils in the Mekong Delta. Furthermore, moisture desiccation resulting from land-use change and subsoil excavation for drainage probably promotes soil oxidation followed by acidification. We prepared air-dried soil moisture condition actual acid sulfate soils in the Mekong Delta to evaluate acidification and the release of acids and metals with drying. The pH values of the deepest horizon in the Hydroaquentic Sulfaquepts drastically dropped and greater concentrations of Al and Fe were released with drying. It was a common change from the sulfidic horizon to the sulfuric horizon. A large increase in Al release without a drop in pH after drying was observed in the sulfuric horizons of the Typic Sulfaquept, which developed on the oldest land in the Mekong Delta. Acidification by oxidation of reduced sulfur compounds might be compensated mainly by exchangeable Al and/or by the dissolution of Fe and Al oxides. In contrast, the concentration of Al increased slightly by drying in the sulfuric horizons in the Hydroaquentic Sulfaquept, which developed in the newer delta. The exchangeable basic cations in these soil horizons might still be effective in compensating for the protons produced by the oxidation of pyrite. The difference in the Al released by drying between the two sulfuric horizons might be attributed to the ripeness of the acid sulfate soils. The ripeness of the soil on the older delta might be higher than that on the younger delta. In this study, drying of acid sulfate soils, even in the sulfuric horizon, can promote metal release due to the exchange by protons derived from the oxidation of reduced sulfur compounds. However, further acidification might be compensated by a substantial amount of exchangeable cation and oxide dissolution.

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“…2000). In the dry season, water table depletion results in strong acid soil reactions as a result of oxidation of reduced sulfur compounds (Hanhart et al . 1997; Tipping et al .…”

Section: Introductionmentioning

confidence: 99%

Effects of drying on the release of solutes from acid sulfate soils distributed in the Mekong Delta, Vietnam

Kawahigashi¹,

Minh²,

Nguyen³

et al. 2008

Soil Science and Plant Nutrition

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“…Moreover, the already high cost of production of irrigated rice would increase further due to the cost of additional irrigation which may result in net loss in terms of economic return to the farmers. Some areas of the lower basin are also vulnerable to acidification -a consequence of how water moves rather than how much is available (Hanhart et al 1997). Changes to flow characteristics through reductions of supply or the construction of irrigation infrastructures might add productivity in some areas but may cause it to decline elsewhere.…”

Section: Risks Due To Increased Irrigation Diversionmentioning

confidence: 99%

Adaptation to climate change for food security in the lower Mekong Basin

2011

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Variability in water cycles driven by climate change is considered likely to impact rice production in the near future. Rice is the main staple food for the population in the lower Mekong Basin and the demand for food is expected to grow due to increase in population. This paper examines the impact of climate change on rice production in the lower Mekong Basin, evaluates some widely used adaptation options, and analyses their implications for overall food security by 2050. Climate change data used in the study are the future climate projection for two IPCC SRES scenarios, A2 and B2, based on ECHAM4 General Circulation Model downscaled to the Mekong region using the PRECIS (Providing Regional Climates for Impact Studies) system. In general, the results suggest that yield of rainfed rice may increase significantly in the upper part of the basin in Laos and Thailand and may decrease in the lower part of the basin in Cambodia and Vietnam. Irrigated rice may not be affected by climate change if increased irrigation requirements are met. Negative impact on the yield of rainfed rice can be offset and net increase in yield can be achieved by applying widely used adaptation options such as changing planting date, supplementary irrigation and increased fertilizer input. Analysis of the projected production, considering population growth by 2050, suggests that food security of the basin is unlikely to be threatened by the increased population and climate change, excluding extreme events such as sea level rise and cyclones

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“…The total volume of leachate depends on management techniques, but is especially high when raised beds are used to cultivate upland (terrestrial) crops (Le Quang Minh et al 1997). As a result, pH values of 2-3 and dissolved aluminium concentrations over 45 mg L −1 (and locally 90-135 mg L −1 ) are frequent (Hanhart and Duong Van Ni 1993;Hanhart et al 1997;Le Quang Minh et al 1997;Tran Triet et al 2000). Drainage water from reclamation of one hectare for rice reduced the pH of 4 km of surrounding canals to around 4 (Hanhart and Duong Van Ni 1993).…”

Section: The Problem Of Acid Sulphate Soilmentioning

confidence: 99%