Problem Soils of the Paddy Fields in the Eastern Coastal Plain of the Red River Delta, Vietnam

“…The Red River is the biggest river system in the north of Vietnam. While mountainous topography dominates in the upper river basin, the delta plain is built up by alluvial soils, including fluvial and marine deposits (Haruyama et al . 2006).…”

Section: Discussionmentioning

confidence: 99%

Arsenic contents and physicochemical properties of agricultural soils from the Red River Delta, Vietnam

Phương

Kang

Sakurai

et al. 2008

Soil Science and Plant Nutrition

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To evaluate arsenic (As) levels in agricultural soils of the Red River Delta in northern Vietnam, surface (0-5 cm) and subsurface (20-25 cm) soil samples were collected from 18 paddy and six upland fields on both sides of the river. As a reference, forest soils were also sampled at two sites of the upper river basin. The total As contents of approximately 80% of the surface paddy and upland soils exceeded the maximum allowable limit for Vietnamese agricultural soils (12 mg kg -1 ). Arsenic contents higher than 35 mg kg -1 were found in soils from the Hungyen and Hanam provinces, where high As levels in the groundwater have also been reported. Sequential fractionation of As in these soils indicated that the amounts of As in the phosphateextractable and residual fractions were higher than those in the forest soils. Elevated total As contents were also detected in the surface soil of a paddy field near a fertilizer factory in Hanoi (site P10). The amount of HCl-extractable As in the surface soil at P10 corresponded to 84% of the total As, while the proportion never exceeded 40% at other locations. In the surface soil at P10, most of the As was part of the phosphateextractable fraction. Significant correlations between the total As contents of the upland soils and their noncrystalline Fe oxide contents (r = 0.652, P ≤ 0.05) and between As levels of paddy soils and their crystalline Fe oxide contents (r = 0.544, P ≤ 0.01) were observed. Overall, the present study indicated that although serious As pollution was not found in the studied area, there were some point pollutions caused by industrial activities, in addition to some non-point pollutions resulting from high As concentrations in the groundwater. In addition, Fe oxides in the soils are important factors affecting the As contents of agricultural soils in the Red River Delta.

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“…Because an increase in ECe and total soluble cations coincided with an increase in SAR, Na + was considered to be mainly responsible for salt accumulation in the surface paddy soils Kosaki 2007 andFunakawa et al 2000). Moreover, a highly significant positive correlation between the watersoluble cation Na + and water-soluble anion Cl -indicated the influence of NaCl from seawater on the ECe, ECw and total salt content (Haruyama et al 2006). There were positive correlations between ECe and SAR, total cations and total anions.…”

Section: +mentioning

confidence: 99%

“…The important role of elevation in salt accumulation in soils has been reported by many authors, including Funakawa et al (2000), Haruyama et al (2006), Funakawa and Kosaki (2007), Li et al (2007), Sugimori et al (2008), Zheng et al (2009) and Moral et al (2010). However, there is limited information on the influence of minor differences in elevation (on the scale of centimeters to decimeters) on soil salinization, especially for saline soils adjacent to lagoons, such as those in the Thua Thien Hue region.…”

Section: Introductionmentioning

confidence: 99%

Spatiotemporal variability in soil salinity and its effects on rice (Oryza sativa L.) production in the north central coastal region of Vietnam

Nguyen

Watanabe

Funakawa

2014

Soil Science and Plant Nutrition

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To better understand the adverse impacts of soil salinization and promote rice (Oryza sativa L.) production in crops from the north central coastal region of Vietnam, the spatiotemporal variability of soil salinity and its effects on rice production were investigated. Experiments were conducted at 19 plots widely distributed in the Quang Phuoc commune, in the Quang Dien district of the province of Thua Thien Hue in the north central coastal region of Vietnam. We determined the elevation of the 19 plots to evaluate the influence of elevation on salt accumulation. Soil samples from the 19 plots were collected in January, May and September 2012 and 2013 to study the spatiotemporal variability of salinity. A soil saturation paste was prepared and used to measure electrical conductivity (ECe). The elevation measurements obtained suggest that the research site could be divided into low-and high-elevation plots, with elevation of the low-elevation plots ranging from -0.52 to 0.07 m and the highelevation plots from 0.26 to 0.86 m (one of the sampling plot was designated with an elevation of 0 m and the elevations of the remaining 18 plots were measured relative to that). ECe was high at low elevations. In conclusion, although the differences in elevation between the 19 plots were very small (centimeters to decimeters), they still led to large differences in soil salinity levels. In the high-elevation plots, soils were irrigated with freshwater, thus maintaining low ECe levels throughout the year (< 1.0 dS m −1). In contrast, in the low-elevation plots, soils were subject to seawater intrusion, resulting in high ECe levels in all seasons (> 1.9 dS m −1 ). We recommend several solutions to limit the unfavorable effects of salinity and promote rice production. First, a comprehensive dike system should be constructed along the lagoon to prevent seawater intrusion onto land. Second, it will be necessary to construct adequate drainage facilities in the depressed areas to promote rapid water drainage into canals during and after flooding and irrigation. Third, because ECe was high from May to September, adequate fresh irrigation water should be frequently supplied to lower the ECe during this period.

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Problem Soils of the Paddy Fields in the Eastern Coastal Plain of the Red River Delta, Vietnam

Cited by 5 publications

References 12 publications

The earthworm species Metaphire posthuma modulates the effect of organic amendments (compost vs. vermicompost from buffalo manure) on soil microbial properties. A laboratory experiment

The earthworm species Metaphire posthuma modulates the effect of organic amendments (compost vs. vermicompost from buffalo manure) on soil microbial properties. A laboratory experiment

Arsenic contents and physicochemical properties of agricultural soils from the Red River Delta, Vietnam

Spatiotemporal variability in soil salinity and its effects on rice (Oryza sativa L.) production in the north central coastal region of Vietnam

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