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Cadmium Immobilization in the Rice – Paddy Soil with Biochar Additive

Thi Khac Vu, Lan Phuong Dinh Thi, Hang Nga Nguyen Thi, Thanh Hoa Nguyen

Journal of Ecological Engineering

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2022

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Vol. 23, nr 4

85--95

EN

Cadmium (Cd) is toxic for humans, but its effects on the yield and quality of rice under contaminated irrigation conditions remain uncertain. In this study, paddy soils in the Red River Delta (Vietnam) were selected for experiments with the purpose of understanding the effects of Cd contaminated irrigation water on growth, yields, and grain Cd accumulation. In addition, biochar was produced from rice husk (BRH) and rice straw for preventing Cd infiltration into rice was also studied in this experiment. A field experiment was established with applicated BRH and straw into polluted paddy soil, as a result the Cd content in grains reduced significantly. The Cd contaminated soil was added to the BRH and rice straw (RS) with six ratios, including: (1) RS 2.5%, (2) BRH 2.5%, (3) RS-BRH: 1.25–1.25%, (4) RS 5.0%, (5) BRH 5.0%, (6) RS-BRH: 2.5–2.5%, (w:w). Besides, three content levels 0.01–0.05–0.5 mg/L of Cd in irrigation water were applied throughout crop season. The results showed that the Cd accumulation in rice was in the following order: roots > stems > seeds. With 3 contaminated irrigation levels which were applied, the Cd concentrations of 0.05 mg/L and 0.5 mg/L affected plant height and yield. However, the Cd content in grains under contaminated soil condition can be controlled from 82.47–83.94% by applying a BRH ratio from 2.5–5% (w:w).

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Reforming specialized inspection procedures to improve business environment in Vietnam for trade facilitation implementation

Nga Le Thi Viet, Huy Dinh Tran Ngoc, Hang Nga Nguyen Thi, Lan Leng Thi, Thach Nguyen Ngoc

Management

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2021

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Vol. 25, no. 1

234--258

EN

Our study aims to analyze and assess the process of reforming the specialized inspection procedures in Vietnam which is included in Vietnam’s trade facilitation implementation program, and suggesting some recommendations for Vietnam to do the reform to improve business environment and enhance Vietnam’s national competitiveness. By synthesizing and analyzing secondary data from creditable sources such as World Bank, UNESCAPE, UNCTAD, WTO, VCCI, General Department of Vietnam Customs, as well as interviewing officials from Ministry of Industry and Trade of Socialist Republic of Vietnam, etc. Ha and Lan (2021) stated Economic regulatory reform in Vietnam started in the early 1990s and accelerated when the country shifted its focus to economic integration policy by acceding to the World Trade Organization (WTO) in 1995 and engaging in regional free trade agreements in the Association of Southeast Asian Nations (ASEAN). After analyzing and assessing the real situation of Vietnam’s trade facilitation and specialized inspection reforms, this paper would like to suggest some recommendations to continuously implement specialized inspection reforms, implement trade facilitation, improve Vietnam’s business environment and enhance Vietnam’s national competitiveness.

3

Sandy Soil Reclamation Using Biochar and Clay-Rich Soil

Thi Diep Pham, Hang Nga Nguyen Thi, Viet On Tran, Van Loc Nguyen, Viet Anh Nguyen, Lan Phuong Dinh Thi, Van Nguyen Vu

Journal of Ecological Engineering

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2021

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Vol. 22, nr 6

26--35

EN

The investigations on the effects of biochar application in improving the physio-chemical properties of soil have been carried out in many studies; however, there are very few studies on the combined use of both biochar and clay-rich soil for poor nutrient soil reclamation. Therefore, this study demonstrates improved water retention and nutrient retention of sandy soil by using biochar and biochar combined with clay-rich soil. The experiments were conducted on a small scale (greenhouse) with nine different application rates of biochar and clay-rich soil were mixed and then cultivated peanut, along with the drip irrigation technique using field moisture limit (about 70-80%) was applied under the condition of ensuring a sufficient supply of NPK for plant’s growth. The results showed that at the rates from 10.0-15.0% (w/w) clay-rich soil mixed with from 0.5-1.5% (w/w) of biochar applied to the tested sandy soil resulted in the positive effects on soil water holding, bulk density, permeability, pH, CEC, OM, total N, total P and peanut yield. The physical and chemical characteristics of the tested sandy soil have been improved by time and the application rate of 10.0% clay-rich soil and 0.5% biochar had the highest efficiency of pod fresh weight and pod dry weight during three studied seasons.

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Rice Growth, Grain Zinc, and Soil Properties under Saline Irrigation Conditions

Thi Lan Phuong Dinh, Hang Nga Nguyen Thi, Nguyen Hoa Thanh, Nguyen Lien Thi

Journal of Ecological Engineering

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2021

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Vol. 22, nr 9

59--70

EN

This research evaluated rice growth and yield as well as Zn accumulation in both soil and grain under saline water irrigation conditions. The experiment consisted of a series of pots containing rice plants and paddy soil, with the application of irrigation treatments of five different salinity levels (1.5, 2, 3, 4, and 5‰ with a drip irrigation system). The results show that the salinity accumulation levels in soil can increase by up to 2.8‰ following the application of 5‰ salinity irrigation water during the development stages. Besides, this study also aimed to evaluate the influences of saline water irrigation on the observed rice yields, plant height, leaf length, and leaf width. In the results, irrigation with 3‰ saline water reduced potential rice yield by 58.6% and the length of rice leaves by one-third. Higher salinity of 4‰ in the irrigation water produced only 24% of average potential productivity, and 5‰ water salinity resulted in no yield. Furthermore, salt stress limited the mobile Zn content in paddy soil, reducing the Zn accumulation in grains by between 36.27% and 83.21%. Thus, the study shows that controlling salinity in irrigation water management is essential for controlling the yield and nutrient Zn content in rice grains.