20

Up one level

Assessment of Cu, Zn content in alluvial soils of Red and Thai Binh rivers

Analysed results from 24 alluvial soil samples in Red and Thai Binh rivers on total and available Cu, Zn show that: In alluvial soils, total Cu content changes from 18,00ppm to 43,50ppm and total Zn content changes from 42,25ppm to 119,50ppm. Comparing with Vietnam limit 2002 for agricultural soil, all 24 samples haven’t been polluted, but alluvial soils in Thanh Tri may have been affected of Cu and Zn metal. Content of available Cu in 24 samples changes from 9,41ppm (TT03) to 17,80ppm (TT01) and available Zn changes from 7,96ppm (KX01) to 29,95ppm (TT01). They haven’t been depended on the content of total Cu, Zn but depended on some characteristics of soils. This available Cu content maybe toxic for plant. Between total Cu and total Zn have an positive correlation, r = 0,92.

Assessment of water environmental quality in Dong Anh district, peri-urban of Hanoi city

Water samples including ground-water, surface water in lakes and ponds and water in the irrigation systems are collected from different places in Dong Anh district. The chemico-phisycal dates and heavy metals in water samples are analysed. The study results show that water environmental quality in Dong Anh district has been polluted, especially waste water untreated from industrial areas; typicalIy, there have shown the waste water samples from the Equilized Company Tien Ha in Duc Tu commune.

Cadmium content in Mekong river delta flooded rice soils and warning of cadmium contamination in soils

The long-term application of phosphorous fertilizers in the intensive production of rice in the Mekong delta may have resulted in cadmium contamination of the soils. To assess the contamination, a survey of the phosphorous fertilizer application and the extent of the resulting soils were conducted. Using GF-AAS, the cadmium concentration in the analyzed soils was found, it ranges from 0.01 to 0.56 mg kg-1. The alluvial soils were found to contain significantly cadmium content than saline soils, which consistently showed the lowest level of contamination of this heavy metal. The concentrations were lower than the critical values considered by Vietnamese (TCVN-2000) and the international levels (EC Directive, Canada), but the results of the present study strongly indicate an anthropogenic impact on soil cadmium levels. Concerning with food-chain contamination should be evaluated more closely, especially the areas with dykes. Because these areas appear a potential Cd contamination of the ecosystems.

Characteristics of coastal arenosol soils and present utilization in Northern Central region

Extent of coastal arenosol soils in the Region is 205.698 ha, accounting for 41,5% of all Vietnam's coastal arenosol soils. Natural fertility of coastal arenosols soils has an upward tendency in organic matter, total nitrogen, total phosphorus, soluble phosphorus and CEC by compansion with that's in sixties but is still low. Although there is soil fertility constraint, with even relief, lisht coarse texture and easy access, some 79.076 ha of this soil category has been utilized in agriculture of which 60.818 ha for rice, 49.621 ha for protective forest. Unused soil has an extent of 41.775 ha, including 35.064 ha sandy dune. Economic efficiency per area unit has been increasing but is still low in comparision with country’s average, which ranges between 15-20 millions VND/ha.

Clay mineral composition of soils derived from limestone in the North of Vietnam

Study on clay mineral composition plays an important role in soils genesis research, in determining the soil fundamental physical and chemical properties and soil potential fertility. Until now, very few studies have been carried out on the clay mineralogy in the soils of Vietnam, especially on the soils derived from limestone. In this study, 6 typical soil profiles of the soils derived from limestone were collected in the North of Vietnam. The clay mineral was analyzed by the X-ray diffraction (XRD) method; Soil samples were taken from each horizon of profiles and air-dried; Specimens of soils had treated by Mg-saturated, K-saturated, Mg-saturated after solvation with glycerin and K-saturated specimen was after heating at 330oC and 600oC. The results showed that Kaolinite was a predominat mineral in the soils derived from limestone, occupied more than 80% in the clay fraction.

Current situation of hydro-structures in water resources systems serving shrimp culture in coastal provinces of North Vietnam

The paper presented some results on investigation, assessment of current situation of hydro-structures in water resources systems serving shrimp culture in coastal provinces of North Vietnam. The four popular models of shrimp culture (extensive, improved extensive, mid-intensive and intensive shrimp culture) in Northern coastal provinces are investigated and assessed. The prevail layouts of water resources systems in shrimp culture areas and their main items have been analysed and assessed. The improved extensive shrimp culture model proved to be the most suitable one for Northern coastal provinces. For sustainable development, it is necessary to build water supply systems separately from drainage systems in those areas where the model is being applied. Waste water from shrimp ponds must be treated before being released to the sea.

Effect of four kinds of herbicides (Rafale, tillers, cantanil, satunil) on alluvial soils' microbial activity and carbon nitrogen biomass in Dong Thap province

A field experiment was conducted to study the effect of four kinds of herbicides on soil microbial activity and carbon-nitrogen biomass of alluvial soil in An Phong village. Thanh Sinh district, Dong Thap province in 2000 Summer-Autumn cropping season; the experiment was arranged a completely block randomized design with four replications and five treatments consist of four kinfs of herbicides (Rafale, Tillers, Cantanil, Satunil) and weed-handle control. The results showed that four herbicides decreased bacterial, fungal, actinomycetal and algal propagule numbers and they also reduced soil microbial carbon-nitrogen biomass. Rafale and Tillers toxicity affected on bacterial and fungal propagule numbers seriously and their toxicity prolongation on soil microbial biomass during rice cultivation time; Cantanil had the lowest toxicity on microbial numbers and soil biomass.

Effect of phosphate to the growth and yield of short day verieties of rice in midland region of Bac Giang

The research was carried out in some districts of Bac Giang provine during period of 2002-2003. Two short day varieties of rice were used (DT 122 and VL20). There are 7 treatments in the experiment, three phosphorous doses from 60-100kg P2O5/ha, each level with two ways of using: - Mix superphosphate together with organogenic fertilizer 2 months before use; - Phosphorus presowing fertilization. The results are following: 1. Treatments, in which rice was fertilized with phosphorus gave high yield (even 0.99 tons/ha higher than without phosphorus); 2. DT 122 reachs the yied of 5.91 tons/ha at the dose of 80kg P205/ha. Variety VL20 gives the highest yield at the level of 100kg P2O5/ha; 3. At the same dose of tons/ha higher than, if superphosphate was mixed together with organogenic fertilizer 2 months before fertilizing, rice grew more stronger, the yield of VL20 was 0.24 tons/ha higher than in comparison with phosphorus presowing fertilization.

Effect of urea application on phytoplankton activity and nitrogen losses in rice field

Poor N fertilizer-use efficiency is characteristic of rice cultivation system. As documented low efficiency is largely attributed to rapid losses of applied N from NH3 losses water pH is a major determining factor, from which photosynthetic aquatic biomass has a key role in increasing the floodwater pH. The research was conducted on alluvial soil at Chau Thanh, Can Tho during wet season 2002. The biomass of phytoplankton reached maximum within 2-4 days after urea application. The biomass of phytoplankton at the CuS04 treatment was lower than that of the control. Algaecides are suggested to test for reducing NH3 volatilization loss. The noticeable amount of ammoniacal-N can remain in floodwater within 6-7 days after fertilization. Consideration of the flood water N concentration will greatly help to minimize N losses by leaching or run-off from lowland rice soils.

Effects of application of different fertilized formulas on earthworms in soil of Hiep Hoa station for improving degraded soil, Bac Giang province

The paper presents effects of fertilized formulas application on earthworms in soil of Hiep Hoa Station for improving exhausted soil, Bac Giang province. The results were 9 of earthworms species belonging to 8 genera, 7 families were found in four formulas of fertilizer application. Among these formulas, the highest earthworm species were found in formula 4 and 6 (7 species) and the lowest species were found in formula 7 (3 species). There were differences in earthworm species between soil with and without byproducts. The paper also suggests that formula 5b be increased of earthworms in soil the most appropriate for exhausted soil. This formula have very high recorded earthworms species (6 species) as well as density (34, 4 individual/m2) and biomass (22, 27 gr/m2). Among earthworm species, Pheretima acidophila is a species with the highest abundance of both quantity and biomass; and Allolobophora parva is species with very high abundance of quantity in soil with formulas of fertilizer application. NPK have major effects on not only ameliorating quality of exhausted soil but also increase of earthworms in soil .

Effects of land use/land cover changes and practices on sediment contribution to the Tri An reservoir of Dong Nai watershed

This study is aimed at assessing factors contributing to reservoir sedimentation as well as deriving the predictive models of reservoir sedimentation using land use factors in Dong Nai watershed as case study. It is especially important in the Dong Nai watershed where the soil is highly erodible and forest conversion for agricultural cropping is in serious condition. The mathematical statistical models for predicting reservoir sedimentation were formulated through multiple regression analysis using data from Tri An reservoir to correlate with hydrological and various land use parameters during the period 1990 to 1998 . All significant variables (annual rainfall, X1-, forestland, X3, natural forest, X4, Plantation forest, X5, and agricultural land, X6) have correlation to the RS with r-value higher than 0.5. Among the factors contributing to the reservoir (-0.92), while agricultural and RS have positive correlation (0.936). The annual rainfall and RS have the lowest positive correlation (0.78). Among the land use and hydrological factors used in deriving the relational function, only three parameters were statistically selected as significant factors for the prediction of reservoir sedimentation (RS). These are average annual rainfall (X1), forestland (X3), and agricultural land (X6).

Effects of multipurpose organic microbiological fertilizer (MOMF) for peanut on the exhausted soil in Bac Ninh

- Multipurpose organic microbiological fertilizer (MOM F) had an effect to decrease soil acidity, to increase effective microorganisms amount in soil and to improve the soils fertility in Bac Ninh; - MOMF increased germination rate 17,3%, plant height 35,81 %, plant weight 35,12%, effective nodule quantity 76,1%, seed/plant 34,49, fulfilled seeds 9,46%, biomass yield 8,27T/ha (47,9%), seed yield 0,46 T/ha (33,82%). Decreased disease rate 16,42%.

Heavy metal content in soils and vegetables in the Hanoi peri-urban area

This study was carried out within the framework of the RURBIFARM (ICA-4-CT2002-10021) EU granted project by National Institute for Soils and Fertilizers team. The results of study showed that soils in the Hanoi peri-urban area, which affected by waste water (Thanh Tri) and intensive cultivation (Tu Liem) are still considered as the clean soils (safe for agriculture purpose) when referring to Vietnam and International standards. However, 8 heavy metals were analyzed in vegetables: Cu, Zn, Pb, Cd, Cr, Hg, As; Pb and Cd should be warned a possible contamination because they exist at and or higher than maximum limit (Vietnam standard 1998/WHO 1993). In Tu Liem, Pb content in 13 vegetable samples (in 18 samples taken) was detected at the higher maximum limit, of which Pb content in most herb vegetable and leafy-cooked vegetables was detected at higher maximum limit. In Thanh Tri Pb content in 7 vegetable samples (in 8 samples taken) was detected at the higher maximum limit. For Cd content in vegetable: 11 samples in Tu Liem (in 18 samples taken) were found at higher maximum limit. Cd in leafy-cooked vegetable was higher than that in herb and noncooked vegetables. 3 samples in Thanh Tri (in 8 samples taken) were found at higher maximum limit. Cd in herb vegetable was higher than that in leafy-cooked and morning glory.

Identification of critical levels for soil quality indicators for assessment of sustainable tea cultivation

The objective of this study is to identify soil quality indicators, critical levels for assessment of sustainable tea cultivation. The study based on the theory that crop yield responds to soil conditions. The study results indicated that long - term tea cultivation resulted in declining soil quality and crop yield. The lower crop yield in 40 years old tea is mainly due to soil degradation. Therefore, if tea receives enough fertilizer inputs, the yield will be higher compared to its current yield. Economic analysis indicated that benefit cost ratio of 40 years old tea is only marginally above the "break even" point. Any further decline in soil quality is likely to reduce yields to the point where system would no longer be economically viable. Among soil quality indicators as being sensitive to cultivation-induced changes, the organic C, total K, available P and plant available water capacity were key soil quality indicators for modeling the economic sustainability of tea cultivation.

Land evaluation and orientation of agricultural land use in My Hao district, Hung Yen province

My Hao is an agricultural district of Hung Yen province belong to ecological zone of Red river delta. The land use management and orientation of agricultural land use in this district is very important. Agriculture land of My Hao district, Hung Yen province is evaluated by guidelines for land evaluation of FAO. There are 19 land mapping units in My Hao district. Based on the results of land evaluation the orientation of agricultural land use up to 2010 years. Wals determined five optimum land utilization types were selected for agricultural development. The coefficient of land use will increase from 2,58 at present time to 2,94 up to 2010 year.

Merging decision support system for agrotechnology transfer (DSSAT) with GIS for evaluation of land use planning

A case study on merging decision support system DSSAT with GIS technique is aimed to test for the ability to delineate the spatial distribution of predicted rice yield at different fertilizer levels in the area, which will help for the dicision makers in soil fertility evaluation, land use planning, and develop the strategies in fertilizer use, crop productions,.. The results of this study show that GIS can link with decision support system by using the the output results of DSSAT on yield of rice at different fertilizer levels, which assigned on different land mapping units combined with predicted climate. Sixteen land mapping units were assigned with output result of rice yield at five levels of N fertilizer (0, 30, 60, 90, 120 kgN/ha), created from DSSAT, by Idrisiw to create five maps of rice yield at five N fertilizer levels.

Mineralogical characteristics and the variability of acid sulfate soils (ASSs)

ASS is one of the important soils in Viet Nam. Acording to different conditions of each ASS region : their genesis, origin, weather and climate, field nanorelief... and human activities during ASSs evolution process, some different ASSs types may be formed. In the study, the author is dealing with two contents: (i) the main minerals maybe indicator to each ASS type and (ii) clay minerals in ASSs of Viet Nam, especially in Southern region of the country. Some conclusions are noted as following: 1. Pyrite, forming indicator for potential ASSs, are FeS2 microcristal groups under the form of intact spherical shape or decomposed into individual microcristals; 2. Ferrous and Ferric sulfates (with very low pH) are proper indicator for young active ASSs, when no Jarosite formed yet; 3. Jarosite, common forming indicator for developed active ASSs, are small cristals KFe3(OH)6(S04)2, coating around root chanels and on clay particles in soil; 4. Sulfuric horizon with Jarosite and Goethite (alpha-AI2OOH) mottles in the upper part, readily identified in the field, may be indicator for strong developed active ASSs; 5. Sulfuric horizon, as above-mentioned in conclusion 4, but with dark-yellowish color, added hematite (alphaFe203) mottles in the upper part and greyish - white mottles of Vivianite (Fe3(P04)28H20) in the lower one, may be the specific trait for some developed active ASSs altered by rice planting; 6. Dark-yellowish horizon appears near of soil surface with red and yellow mottles in the lower part, may indicate for rice planting old ASSs in river-marsh origin areas; 7. AI-bearing minerals in ASSs are almost dissoluted basic aluminium sulfates. They can strongly increase soil solution pH and release A13+, a very toxic matter or plants; 8. Clay minerals of ASSs in Vietnam are also abundant. In potential ASSs, Illite gets the highest ratios. Kaolinite often predominates in developed ASSs. The lowest contents always belong to other clay mineral groups having larger sizes.

Oscillatoriaceae (order family Nostocales) in the cultivated soils of some districts of Dak Lak province

1. The species composition of Oscillatoriaceae family in the cultivated soil of Dak Lak province is rather diverse. There are 41 species and sub-species found, in which dominant genera are Oscillatoria and Lyngbya; 2. Of the cultivated soils of Dak Lak province, the rice-cultivated soil has the most species of Cyanobacteria, the cotton-paddy soil has the second and the coffee- planted soil has the least.

Phosphorus fixation and transformation in some soil types of Vietnam

Phosphorus is an important nutritient for plant growth. Phosphorus deficiency is often observed in tropical soils because of high fixation capacity of soils. So that farmers usually fertilize crops with phosphate to improve yields. However that also effects on dynamic and Phosphorus accumulation in soils. To understand these effects, the research is carried out on some soil types of Vietnam. The results showed that the most of the studied soils have high phosphorus fixation capacity. The fixation capacity of soils decreases from ferralit acrisols to xanthic ferrasols, gleyic fluvisols, eutric fluvisols and haplic arenosols. In term of fractions, the fract on of Fe-P is predominant in the most of the studied soils, except xanthic ferrasols. The fraction of Al-P is higher than Ca-P in soil With highly ferralitization intensity in rhodic ferrasols, but lower in soils with weakly ferralitization intensity in eutric fluvisols and haplic arenosols. Logged water has high effects on phosphorous fractions in soils. The contents of Org-P, Ca-P and Al-P decrease but the contents of Fe-P increases due to logging. Phosphorous applications also have the significant effect on the sorption capacity as well as the fractions of phosphorus in soils. At high rates of applied phosphate, all the fraction s of phosphorus increase significantly, especially Fe-P and Ca-P.

Physico-chemical properties of soil and water in shrimp ponds at Thoi Binh, Cai Nuoc and Dam Doi districts of Ca Mau province

As the extremely high benefit gaining from shrimp compared to other agricultural production, unprompted converting of rice field to shrimp culture in the saline intrusion areas have been increased enormously. In Ca Mau province, more than 200,000 ha of cultivated shrimp was established in which large areas of potential and actual acid sulfate soils have used for shrimp in rotation with rice and intensive shrimp cultivation. High risk failure of these systems are remaining. Characterization of bottom soil sediment and water column have not much documented. Experiment was executed during dry season 2002-2003 in one shrimp cultivation cycle on two systems of shrimp monoculture and shrimp rice rotation. Shrimp ponds were selected on potential, actual acid sulfate soils and saline soils in different tidal affected regimes. Soils and water samples were taken three times for chemical analysis in laboratory. Experimental results showed that, in general, bottom soil pH of shrimp ponds in potential and actual acid sulfate soils were dropped below 5 after drying. Soil salinity was increased up to 41 mS.cm-1 at the end of shrimp cycle. Organic matter content in shrimp pond was gradually increased in potential acid sulfate soil. Labile organic nitrogen which is easily decomposed to release nitrogen available tended higher in shrimp ponds on acid sulfate soil compared to those in alluvial soils. Water quality was not different in both shrimp cultivation systems. Dissolved oxygen, pH, COD, BOD, total suspended solid, total dissolved solid were recorded in an optimum range for shrimp growth during the dry season. Other factors need to be improved: Salinity varied in large extent (from 6ppt- 37 ppt), alkalinity was below optimum value during the first half shrimp cycle, nitrogen and phosphorus nutrients were low led to low chlorophyll-a content, meaning of effect to natural food chain in ponds. Hydrogen sulfide was found from 0,03-0,71 ppm which was rather not suitable for shrimp.

Soil resources and land use in Trung Khanh district, Cao Bang province

Soil map compilation and land evaluation provide the necessary and important information on biological and nonbiological subjects with their environments (soil and land). In order to sustain the total development and development of agriculture sector, the more effective utilization of natural factor including soil cover and land is required. The studied results on soil map compilation and land evaluation of project area show that: - The third of total area of Trung Khanh district is covered by moderately fertile soils; - The dominant area of this district is covered by degraded soils and bare mountain of limestone. In order to ensure the environmentally sound land use in project area, the integrated measures should be implemented.

Some study results on heavy metals in the world

Study on effect of waste water irrigation of Hanoi urban on yield, quality of rice and vegetables

Content of heavy metals was highly uptaken on plant as it was used waste water resources. Irrigating waste water of To Lich and Kim Nguu rivers not only affects actively on growth and yield of plant but also positively on quality of crop products . While waste water irrigation from Van Dien Satery and Phosphorus and Net Soap Factory maked growth of crop and decrease of the yield as well as increase of accumutation of heary metal in product.

Study on nutrient balance for robusta coffee in productive stage on basaltic soil of Western Highlands of Vietnam

Based on the total of nutrients added to soil as well as amount of nutrients loss, the research results (in 2002) showed that application of only organic fertilizer without chemical ones resulted in deficiency of major (N, P, K) and secondary (Ca and Mg) nutrients for coffee. Application of 270-300 kg N, 100-150 kg P2O5 and 270-300 kg K20 in combination with 5000 kg of cattle dung ha-1yr-1 has led to surplus of 15.8-27.8% N, 7.3-18.9% P and 0.5-6.7% K, but lack of 41.6-58.1 kg Ca and 15.2-31.1 kg Mg in comparison with the requirement of plant.

Study on the application of participatory land use planning (PLUP): Case study in Vinh My village, Vinh Loi district, Bac Lieu province

Land use planning related to the production activities in the rural area, and to the livelihood of the farmers who living in the area. Therefore, land use planning should be carried out carefully in order to meet the objectives of the government, but also to the interest of the community, especially at the village level for socio-economic development. Study on "The application of participatory land use planning (PLUP) in case study at Vinh My A village, Vinh Loi district, Bac Lieu province" were done to respond to the issues above. The results of study showed that the area of shrimp culture have been expanded into large scale due to the change of physcial conditions such as drought spell, salt water intrusion. In the area where rice cultivated inefficiently has been converted to the shrimp cultivation and has given more benefit as compared to rice. From that it appeared the confliction between the objectives of the government and the interest of farmers in term of the land use planning. In this study show that participatory rural appraisal (PRA) was as a tool for PLUP in order to indicate the resources of household in term of physical and socio-economic conditions. A procedure of PLUP were built up in this study and can be carried out the land use planning at local levels.

The potassium status in acid sulfate soil in the North of Vietnam

The study focused on following subjects: - To determine the potassium forms; - To determine the potassium potential and the buffering capacity of the soil with potassium; - To determine the influence of the use of potash fertilizer on the potassium status and the yield of rice C70 in acid sulfate soil. Based on the study results on the potassium status in the acid sulphate soil in the North of Vietnam, the following conclusions can be withdrawn: 1. The acid sulphate soil is comparatively high in total potassium. The total concentration of this element is 1.66 - 2.22 %. The quantity of available potassium isn't high, Its average concentration is 11.07 mg/100g soil. The concentration of non-exchangeable is higher. It is 18.27 - 39.28 mg/100g soil in surface soil horizons; 2. The potassium potential in acid sulphate soil ranges from 2.11 to 2.79; 3. The potassium buffering capacity of the acid sulphate soil is high. It ranges from 30.42 to 53.38 me/100g soil)(mol/I)"1/2; 4. The utilization of potash fertilizer in acid sulphate soil had no effect on the concentration of potassium forms except available potassium and on the yield of rice C70.

The results of sustainable cultivation demonstration on slopping land at Ban Peo commune, Hoang Su Phi district, Ha Giang province

The demonstration (carried out in 2001-2002) has accomplished the objectives and the content. It contributes solutions to overcome difficulties in agricultural development on slopping land at the poorest commune of Ha Giang province. - The results of the demonstration bring for the people there the self-confident in accepting and application of new technology to their agricultural production; - The demonstration results determined the role of science and technology development in high degree only when there is tight whole hearted collaboration of extension workers of different level and the farmers. This really bring to the farmers a lot of long-term benefit in different aspects: yield increase, better husbandry, income ... This consequently contribute to the sustainable development on slopping land.

The status of agricultural land use in Viet Yen district, Bac Giang province

Viet Yen is a district, which has advantageous position and land condition to diversify cropping systems and expanding into cash crops. However, land use systems in region have been still in traditional agricultural production with subsistence crops. The need for more employment and wish to increase incomes is behind the growing cash orientation in most cases.