Phosphate Desorption Characteristics of Some Representative Soils of Bangladesh: Effect of Exchangeable Anions, Water Molecules and Solution to Soil Ratios

Establishment of phosphate (P) retention and release capacity of soils is essential for effective nutrient management and environmental protection. In this experiment, we studied the influence of soil properties on P desorption and the relationship between phosphate sorption and desorption. Among the soil series, the Ghior soil had the highest percent clay (59.32%) and free iron oxide (15241 mg·kg–1) content. Along the catena of the calcareous soils, percent clay contents increased. For sorption study, the soils were equilibrated with 0.01 M CaCl2 solution containing 0, 1, 2, 4, 8, 16, 25, 50, 100 and 150 mg·P·L–1 solution. For desorption, three extractants namely, SO42- (0.005 M) as Na2SO4, HCO3- (0.01 M) as NaHCO3 and distilled water were used at extractant to soil ratios of 30:1, 60:1 and 100:1 (v/w). Among the sorption equations, the Langmuir equation showed better fit to the sorption data at higher P concentrations. The amount of phosphate desorbed by all the three extractants increased significantly with the increasing extractant to soil ratios. Phosphate desorption by and water molecules was highly correlated with pH, percent clay and free iron oxide content of the soil. Significant positive correlation (r > 0.64, P L). Phosphate desorption by SO42- and water molecules was also positively correlated with Freundlich constant, N (r > 0.67, P 0 (r > 0.72, P –0.77, P L). The results suggest that freshly sorbed phosphate ions (inner-sphere complex forming species) can be readily desobed by outer-sphere complex forming species like sulphate and bicarbonate ions. Water molecules also desorbed significant amount of freshly sorbed phosphate from the soil colloids.

Release of Arsenic from Arsenic Removal Water Filter Sludge in Soil and Its Uptake by Red Amaranth

There is a major concern among scientists over the elevated levels of arsenic (As) in drinking water in Bangladesh and some parts of India. Investigating the release of As from water filter sludge in soil and its uptake by plants may provide information about the management of As contaminated filter sludge. In this macrocosm study, iron based sludge con- taining granular ferric hydroxide (GFH) was mixed with air dried silt loam surface soil at rate of 0 (control, no sludge), 1.5 and 2.5 t?ha?1 and red amaranth (Amaranthus tricolor L.) plants were grown for 45 days. Addition of filter sludge did not affect the height, fresh weight and dry matter yield of amaranth. However, the highest concentration of As and Fe were found both in shoots and roots of amaranth grown in the pot of the highest rate of sludge treated soil. The con- centration of As, Fe and S was higher in the roots than that in the shoots of Amaranth. Translocation of As, S and Fe in- creased with the rates of sludge application. Elevated concentration of As in sludge treated plants is a sign of environ- mental hazard and should be taken into consideration.

Amelioration of Saline Soil by the Application of Gypsum, Calcium Chloride, Rice Husk and Cow Dung

A pot experiment was conducted to investigate the effect of cow dung, rice husks, calcium chloride and gypsum on soil reclamation and compare the effect of organic and inorganic amendments on soil reclamation during the period of 5th March to 20th April, 2017. The experiment was laid to fit a completely randomized design (CRD) with seven treatments [Reference soil (T0), Cow dung (T1), Rice husk (T2), Gypsum (T3), Calcium chloride (T4), Cow dung + Rice husk (T5) and Gypsum + Calcium chloride (T6)] each having three replications for this experiment. After incubation (45 days), the laboratory investigation was carried out in the Soil, Water and Environment Discipline, Khulna University, Khulna, Bangladesh. Results indicate that the individual or combined effect of gypsum (T3) was more effective in changing EC and SAR. Gypsum application in combination with calcium chloride (T6) improved the soil chemical properties by reducing the EC. Among the treatment, calcium chloride (T4) had a remarkable effect in reducing sodium adsorption ratio and gypsum had a remarkable effect in reducing pH. Cow dung (T1), rice husk (T2), combination of cow dung and rice husk (T5) were less effective to reduce EC, pH and SAR. It’s measured for soils of different soil amendments varied significantly

Microplastic Can Decrease Enzyme Activities and Microbes in Soil

An in vitro study was conducted to investigate the impacts of microplastics on enzyme activities and soil bacteria. The study included four different treatments of microplastics including a control. Different levels of microplastics were applied to the soil ranging from 0% to 5%, to assess the impacts of microplastics on soil enzymes and subsequent soil bacteria. After 30 days of incubation, the soil samples were collected and growth parameters of bacteria were assessed. Activities of β-glucosidase, urease and dehydrogenase enzymes were also determined. Our results showed that the presence of microplastics in the soil significantly reduced bacterial population together with bacterial strains. The activities of β-glucosidase, urease and dehydrogenase enzymes were reduced significantly to approximately 32%, 40% and 50% in microplastics treated soils respectively. Concentration of microplastic has a role to play towards this direction;the higher the concentration of microplastic the greater is the impact on enzymes and soil bacteria. The present study on the microbial soil health vis-à-vis microplastic application indicates that the material can have negative effect on the soil bacterial population of and thus ultimately may jeopardize soil health and crop production.

Interaction between Biochar and Algae on Problem Soil

An in-vitro experiment was conducted to assess the interaction between biochar and algae on a problem soil. Experiments were performed with and without algae to observe the effectiveness of algae for overcoming the challenges posed by problem soils. At the end of incubation periods, the adsorption and desorption of phosphorus (P) on a problem soil vis-á-vis algal inoculation were determined. Our results showed that different types of biochars adsorbed different amounts of P suggesting that the source of biochar played a crucial role in determining its behavior towards P. Tannery waste biochar significantly adsorbed 147% and 35% more P compared to that of the chicken litter and orange peel biochars respectively. Significant reductions in adsorption were observed when the biochar was used in combination with the algae which could be due to the beneficial effects of algae leading to the amelioration of the problem soil. Adsorption was reduced to 34%, 24% and 20% for the orange peel biochar + algae, chicken litter biochar + algae and tannery waste biochar + algae, respectively compared to the corresponding biochars present as a single solid. Phosphorus (P) desorption was also reduced significantly in presence of algal inoculation. Overall our findings suggest that the application of algae along with biochar in the problem soil could reduce the adsorption of P which would influence the availability of P.

Assessment of physicochemical properties of water and their seasonal variation in an urban river in Bangladesh

To assess the magnitude of water quality decline in the Turag River of Bangladesh,this study examined the seasonal variation of physi-cochemical parameters of water,identified potential pollution sources,and clustered the monitoring months with similar characteristics.Water samples were collected in four distinct seasons to evaluate temperature,pH,dissolved oxygen(DO)concentration,five-day biochemical oxygen demand(BOD 5),chemical oxygen demand(COD),electrical conductivity(EC),chloride ion(Cl^(-))concentration,total alkalinity(TA),turbidity,total dissolved solids(TDS)concentration,total suspended solids(TSS)concentration,and total hardness(TH)using standard methods.The analytical results revealed that 40%of water quality indices were within the permissible limits suggested by different agencies,with the exception of EC,Cl^(-)concentration,TA,turbidity,DO concentration,BOD 5,and COD in all seasons.Statistical analyses indicated that 52%of the contrasts were significantly different at a 95%confidence interval.The factor analysis presented the best fit among the parameters,with four factors explaining 94.29%of the total variance.TDS,BOD 5,COD,EC,turbidity,DO,and Cl?were mainly responsible for pollution loading and were caused by the significant amount of industrial discharge and toxicological compounds.The cluster analysis showed the seasonal change in surface water quality,which is usually an indicator of pollution from rainfall or other sources.However,the values of different physico-chemical properties varied with seasons,and the highest values of pollutants were recorded in the winter.With the change in seasonal tem-perature and increase in rainfall,the seasonal Turag River water followed a self-refining trend as follows:rainy season>pre-winter>summer>winter.

Single and Sequential Extraction of Copper by Different Extractants from Different Peat Soil Samples of Bangladesh

A comprehensive in vitro study on single and sequential extraction methods for Cu exraction by different extractants of distinct chemical nature from some peat soils of Bangladesh was conducted to assess the pattern of metal-extractability in drying and wetting sequences. Samples were collected from peat basins of two different districts of Bangladesh (Gopalgonj and Bagerhat) and an incubation study was designed and conducted in which soils were incubated to three alternate drying and wetting cycles for 21 days. Single and sequentially extracted Cu ions in all three cycles and by all three selective extractants were compared. Maximum amount of Cu was extracted in drying days and 1M HCl extracted the largest proportion of Cu from all the soils in each incubation time. Conversely, 1M NH4Cl was the least effective extractant for extracting Cu by both single and sequential process in either day of incubation. Considerable amount of Cu was extracted by 0.005 M DTPA in dry periods. In general, single extraction was found to be more effective in extracting Cu in the alternate drying and wetting cycles from the peat soil samples except for 1M HCl in initial drying days.

Fractionation of Organic Carbon and Stock Measurement in the Sundarbans Mangrove Soils of Bangladesh

Mangrove soils are well known for their high capacity of storing organic carbon (SOC) in various pools;however, a relatively small change in SOC pools could cause significant impacts on greenhouse gas concentrations. Thus, for an in-depth understanding of SOC distribution and stock to predict the role of Sundarbans mangrove in mitigating global warming and greenhouse effects, different extraction methods were employed to fractionate the SOC of Sundarbans soils into cold-water (CWSC) and hot-water (HWSC) soluble, moderately labile (MLF), microbial biomass carbon (MBC), and resistant fractions (RF) using a newly developed modified-method. A significant variation in total SOC (p < 0.001), SOC stock (p < 0.001) and soil bulk density (p < 0.05) at the Sundarbans mangrove forest were observed. In most soils, bulk density increased from the surface to 100 cm depth. The total SOC concentrations were higher in most surface soils and ranged from 1.21% ± 0.02% to 8.19% ± 0.09%. However, C in lower layers may be more resistant than that of upper soils because of differences in compositions, sources and environmental conditions. SOC was predominately associated with the resistant fraction (81% - 97%), followed by MLF (2% - 10%), HWSC (1% - 4%), MBC (~0% - 4%), and CWSC (~0% - 3%). The significant positive correlations between different C fractions suggested that C pools are interdependent and need proper management plans to increase these pools in Sundarbans soils. The SOC stock of the studied areas ranged between 16.75 ± 3.83 to 135.12 ± 28.61 kg·C·m−2 in 1 m soil profile and has an average of 31.80 kg·C·m−2. The substratum soils had more carbon than the upper layers in the Sundarbans wetland due to burial and preservation of carbon by frequent tidal inundation. A higher SOC stock in the soil profile and its primary association in resistant fractions suggested that Sundarbans mangrove soil is sequestering carbon and thereby serving as a significant carbon sink in Bangladesh.

Plant Growth as Affected by Concomitant Movement of Arsenic and Sulphur in Saline Soils

A study was carried out to assess the interaction of Arsenic with excess Sulphur present in saline soil and their impact on plant growth. Two different types of saline soils S1 (2.0 dS/m) and S2 (5.061 dS/m) were collected from the southwestern part of Bangladesh. The experiment was conducted in two parts: in vitro incubation study and pot experiment. Arsenic treatments at the rates of 0, 0.05 and 1.0 mg/L were applied with water. The incubated soils were sequentially extracted with three different extractants, viz, distilled water, 0.01 M CaCl2, and 1 M HCl. 1 M HCl was found to extract the maximum amounts of soluble salts as well as arsenic from the saline soil. Rice was selected as the test plant for pot experiment. An improved variety of rice (BRRI 41) was grown on the experimental soils. Sulphur in saline soil was found to reduce the accumulation of Arsenic by rice plant.

Macro and Micro Nutrient Supply to Soil and Plants from Sugar Mill Mud

The effects of sugar mill mud application on the availability of nutrients for plant uptake were investigated. Mill mud generated from conventional sugar mill operations was applied in three different rates and a leafy vegetable, locally called “PuiShak” or Indian spinach (Basellarubra L.) was grown for 60 days as a test crop in a pot culture experiment. Crop yield and essential nutrients like N, P, K and Zn uptake concentration was determined to come up with an inference that higher doses of mill mud application impose better effect on root and shoot uptake of these elements. A little infraction was observed for nitrogen uptake by plants for the maximum dose.

Effects of Biochar on the Abundance of Three Agriculturally Important Soil Bacteria

An in vitro study was conducted to make a comparative study of biochar and biomass on soil bacteria. The responses of three agriculturally important bacteria viz., Bradyrhizobium, Sulphate reducing and Iron oxidizing bacteria, were studied. Total viable counts were also made. Three different types of biomasses viz., rice husk, rice straw and saw dust, and biochars produced thereof were used for the study. The biomasses or biochars were applied to the soil at a rate of 5 t/ha. The study included seven different treatments of biomasses and corresponding biochars including a control. Total counts were made on the original materials as well as on the treated soils at 30, 60 and 90 days of incubation. Bacterial count was higher in all the biomass treated soils than the corresponding biochar treated ones including control. Although the presence of Bradyrhizobium, sulphate reducing and iron oxidizing bacteria were not noted in the fresh soils, their presence, however, was noted after incubation periods. The counts of all three bacteria are however lower in the biochar treated soils than the corresponding biomass treated soils. The paper discusses about the microbial soil health vis-à-vis biochar application, indicating that the materials exert negative effect on the soil microbial population and thereby likely to jeopardize soil health and crop production.

Animal Manure, Neem Cake, Biochar, Vermicompost or Urea: Choosing the Better Option for <i>Spinacia oleracea</i>Growth and Soil Fertility

Production of safe food through organic farming while maintaining soil sustainability is the crucial challenge of recent time. As such a pot experiment was conducted using animal manure (TAM), neem-cake (TNC), vermicompost (TVC), biochar (TBC) and urea (TU) with control (TC) to assess their capacity to stimulate Spinacia oleracea growth under field condition and their impact on soil fertility. Six treatments: TC, TAM, TNC, TVC, TBC, TU with three replications were used in completely randomized design (CRD). All the plant growth parameters were measured at regular interval up to maturity. Complete chemical analysis of plant tissue, amendments and soil was carried out. Nitrogen use efficiency (NUE) under different treatments was calculated at 45 and 60 days. All the treatments showed statistically significant (P < 0.001) increase in yield over control and urea. The highest plant height (24 cm), leaf area index (0.154), and dry weight (1254 kg/ha) were found at TNC which increased respectively 132%, 258%, 450% over control and 125%, 431%, 448% over urea. TVC was the second best treatment followed by TBC for plant growth. NUE was significantly (P < 0.001) higher in treatment TVC than any other treatments and was higher at maturity than vegetative state. TNC had lower NUE than TVC and TBC but the inherent N content was higher in TNC than TVC and TBC. Uptake of certain macro nutrients showed significant (P < 0.05) positive correlation with plant growth parameters i.e., plant height with P (R = 0.887);leaf area with N (R = 0.957) and P (R = 0.985);dry weight with N (R = 0.996), P (R = 0.994) and K (R = 0.860). Significant (P < 0.001) increase in post-harvest soil C and CEC content was found with all the treatments. The highest availability of N, P and S was observed under treatment TNC. For short duration crop like spinach, TNC is the best option followed by TVC as they release nutrient quickly than TBC and TAM.

Preparation, Characterization and Evaluation of Efficacy of Phosphorus and Potassium Incorporated Nano Fertilizer

Phosphorus and Potassium incorporated nano fertilizer were prepared using zeolite as a carrier material at a laboratory scale. X-ray diffraction (XRD) analysis was done for the characterization and confirmation of the incorporation. Chemical analyses also indicate the sorption of fertilizer material into zeolite. An in vitro incubation study was conducted for 30 days at field moisture condition to see the release of the fertilizer materials and was compared with a conventional fertilizer. The release pattern of nutrients from either source showed a substantial decreasing trend with time although the release of P and K was higher for nano fertilizer than the conventional one. A pot culture experiment with Ipomoea aquatica (Kalmi) was also conducted to see the efficacy of the nano fertilizer in the growth promotion of the plant. Analysis showed higher accumulation of P and K in plants grown with nano fertilizer. Post-effect of nano fertilizer application in soil showed better pH, moisture, CEC, available P and K under nano fertilizer treatment than the conventional fertilizer.

Remediation of Arsenic Toxicity in the Soil-Plant System by Using Zinc Fertilizers

Availability of soil arsenic (As) and plant As at various levels of zinc (Zn) and As applications were examined. A pot-culture experiment with a leafy vegetable, Kalmi (Ipomoea aquatica), on an Inceptisols, was conducted where As was applied with irrigation water at the rates of 0 mg/L (As control), 0.5 mg/L, 1 mg/L and 2 mg/L and Zn was added to the soil as ZnCl2 solution at the rate of 0 mg/L (Zn control), 1 mg/L, 2 mg/L and 3 mg/L during pot preparation. The experiment was conducted in triplicates for 45 days till the plants were grown to maturity. At the end of the experiment the remedial effect of Zn on As toxicity was examined and as such, yield parameters, As and Zn accumulation in Kalmi plants, residual concentrations of As and Zn in soils and plants were measured. It appeared from the present study that there exists an antagonistic relationship between Zn and As i.e., Zn in soils was found to reduce As availability in soils as well as its accumulation in plants, particularly at an elevated application rate of 3 mg/L Zn. The findings could be used as a strategy to mitigate arsenic toxicity in As contaminated soils.

Chemical and Morphological Characteristics of Particulate Matter Suspended in the Air of the Dhaka University Area of Bangladesh

Total suspended particulate matter (SPM) in the urban atmosphere of Dhaka city was collected using a high volume sampling technique for a period of one month (August 2017-September 2017). Chemical characterization of particulate matter (PM) was investigated, and characterized concerning the size distribution, morphological features such as count, total area, average size, perimeter, circularity, aspect ratio (AR), roundness;equivalent spherical diameter (ESD), surface area and volume of PM. The results of elemental analysis showed that the presence of heavy metal in PM was ten to hundred times higher than the standard value prescribed by WHO and USEPA. Several morphological analysis indicated that particles varying in shape from nearly spherical to various irregular shape, had higher surface energy, higher content of Cl and S bearing particles and had a large surface area which can cause greater damage to lungs. The presence of various organic compounds containing functional groups like alcohols, ketones aldehydes, carboxylic acids as well as unsaturated and saturated carbon bonds was observed by FT-IR analysis. Scanning Electron Microscopy (SEM) was used to characterize the morphology of the PM. Agglomerates and shoots type particles were mostly seen in SPM.

Pollution in the Bay of Bengal: Impact on Marine Ecosystem

The study focused on heavy metal concentration in sea water, sea sediment and their toxic effect on sea shells, and on oyster along the east coast of the Bay of Bengal. The hierarchy of heavy metals in sea sediment of the bay showed as: Fe > Zn > Ni > Cr > Pb > Cd. The average concentration of nickel exceeded ERL (20.9 μg·g-1) value and the incidence of adverse effects on biological components exceeded 16.7%. The present study showed that the concentration of Cd, Fe, Pb and Cu in sea water were relatively higher than the standard concentration. The study showed a considerable amount of heavy metals (0.035%) such as Zn, Pb, Cu, Fe, and Mg in sea shells, and oyster which may make them toxic. The toxic effect of Pb and Zn may reduce their growth which is a great threat to marine ecosystem.

Impacts of Different Sources of Biochar on Plant Growth Characteristics

A net-house experiment was conducted to assess the impacts of different sources of biochar on growth and development of plant. Three different types of biomasses viz., cow dung, poultry manure and sewage sludge produced were used for the study. An upland leafy vegetable commonly known as kalmi (Ipomoea aquatic) was used for pot culture experiment. The biomass or biochar was applied to the soil at a rate of 5 t/ha and the pots were arranged following completely randomized design. A number of physical, chemical and physico-chemical properties of the soil, biochar, biomass and plant samples were analyzed in the laboratory. Biochar treated soils showed higher CEC than the corresponding biomass treated ones. Organic carbon in biochar treated soils was also higher. Total nitrogen contents of biomass treatments were higher than biochar treatments. Phosphorus, potassium and sulphur concentrations of the treated soils increased after harvesting. The paper discusses plant growth and agricultural crop production vis-à-vis biochar application, indicating that the materials might not exert similar positive effects as their biomass sources and thereby likely to jeopardize crop production and soil health.

A Feasible Way of Degrading Malathion Pesticide under Laboratory Condition Using Phosphate Solubilizing Bacteria

An experiment was carried out for identification and determination of malathion degrading phosphate solubilizing bacteria isolated from the agricultural fields. In this study, malathion degrading phosphate solubilizing bacteria were identified using NBRIP (National Botanical Research Institute’s phosphate growth medium) media. A number of bacterial colonies were screened from agricultural fields. From primarily screened colonies 4 isolates were identified as phosphate solubilizing bacteria through qualitative and quantitative analysis. The isolated 4 bacterial colonies were inoculated in NBRIP broth media enriched with malathion pesticides to observe degradation of malathion pesticide under incubation study at three different temperatures (25°C, 30°C and 37°C). However, all the four isolates showed capability in degrading malathion pesticide. The study clearly revealed that phosphate solubilizing bacteria can be used in bioremediation of environmental pollution caused by malathion pesticide.

Encroachment of the Buriganga River in Bangladesh

A survey on different aspects of Buriganga River encroachment was conducted in a 300 meter long encroached part of the river located in Dhaka, Bangladesh. A total of 100 respondents were surveyed and three Focus Group Discussions (FGDs) were arranged prior to the semi-structured questionnaire survey. It was observed that almost all of the respondents migrated to the study area. The majority of the respondents had better business opportunity (69.23%) as the cause of encroachment. Significant portions of the respondents occupying the encroached area were found to be landless (36.84%), small businessmen (31.58%) and people with political affluence (26.32%). Major portions (23.33%) of the encroached land were used for industrial development as well as housing and developmental projects. Negative health impact (40%) was found to be the main adverse effect of encroachment of the river. Other adverse effects included economic loss through obliteration of fisheries (35.71%), scarcity of clean water (32.14%), reduction of aesthetic value of the surroundings (25%) etc. For the protection of the river, the majority of the respondents opted for relocation of the industries (46.15%) and enforcement of strict rules and regulations (38.46%).

Heavy Metal Contents of Different Wastes Used for Compost

A study was conducted to assess the heavy metal (As, Pb, Cd, Cr, Cu, Zn and Hg) contents of different sources of wastes generated in Dhaka city which was further used for a compost plant. The study consisted of both field survey and laboratory analyses. Relevant primary and secondary sources of data were collected to identify the source and nature of wastes generated near the compost plant. A total of eight households, ten officers and ten waste collectors were surveyed for data collection. For laboratory analyses, wastes from various socio-economic niches (lower, lower middle, middle and high) were collected. The result showed that wastes generated in the lower income niche contained the minimum contents of heavy metals compared to middle and high niches. The increasing trend of heavy metal contents of the wastes from lower to high income groups has been found to be linked to the life style, attitude, profession, culture and food habit. Most of the heavy metals did not meet the standard level for almost all the niches. Most of the correlations were found to be insignificant between the contents of nutrient element (C, N and P) and heavy metals (As, Pb, Cd, Cr, Cu, Zn and Hg).