BackgroundGroundwater drawn from shallow tubewells in Bangladesh is often polluted by nearby pit latrines, which are commonly used toilets in rural and sub-urban areas of the country.MethodsTo determine the minimum safe distance of a tubewell from a pit latrine in different hydrogeological conditions of Bangladesh, 20 monitoring wells were installed at three study sites (Manda, Mohanpur and Bagmara) with the vertical and horizontal distances ranging from 18–47 to 2–15 m, respectively. Water samples were collected three times in three seasons and tested for faecal coliforms (FC) and faecal streptococci (FS) as indicators of contamination. Soil samples were analysed for texture, bulk density and hydraulic conductivity following standard procedures. Sediment samples were collected to prepare lithological logs.ResultsWhen the shallow aquifers at one of the three sites (Mohanpur) were overlained by 18–23-m-thick aquitards, the groundwater of the monitoring wells was found contaminated with a lateral and vertical distances of 2 and 31 m, respectively. However, where the aquitard was only 9 m thick, contamination was found up to lateral and vertical distances of 4.5 and 40.5 m, respectively. The soil textures of all the sites were mainly composed of loam and sandy loam. The hydraulic conductivities in the first aquifer at Manda, Mohanpur and Bagmara were 5.2–7.3, 8.2 and 1.4–15.7 m/h, respectively.ConclusionsThe results showed that the safe distance from the tubewell to the pit latrine varied from site to site depending on the horizontal and vertical distances of the tubewell as well as hydrogeological conditions of a particular area.

A pot experiment was conducted in the net house of the Department of Soil, Water and Environment, University of Dhaka to find out the interactive effects of nitrogen (0, 30, 60 and 120 kg/ha) and boron (0, 0.5, 1 and 2 kg/ha) fertilizers on the growth and nutrient contents of okra (Abelmoschus esculentus L.). The increase in height of okra was significant (p<0.05) due to combined application of nitrogen and boron fertilizers. Maximum height, shoot and root dry matter yield and uptake of nutrients in root and shoot of okra were observed in treatment 30 kg N/ha with 1 kg B/ha (N30Bi). But, higher doses of fertilizer combinations (60 and 120 kg of N/ ha with B) responded differently. Higher doses of fertilizer combinations significantly (p<0.05) reduced shoot and root growth as well as the concentration and uptake of nitrogen, phosphorus potassium in okra. It could be concluded that the treatment combination of 30 kg N/ha with 1 kg B/ha can be used for better growth of okra. Asiat. Soc. Bangladesh, Sci. 41(2): 173-181, December 2015

A pot experiment was carried out on the rooftop of a building at Charfasson town Bhola to evaluate the growth and yield performance of strawberry (Fragaria ananassa) as influenced by different doses of vermicompost and inorganic fertilizers in the winter season of 2020-2021. Each pot was filled with ten kg soil and arranged in a completely randomized design having seven treatments with three replications. Treatments were T1: Control (-VC), T2: 5 t VC/ha, T3: 10 t VC/ha, T4: 15 t VC/ha, T5: 20 t VC/ha, T6: 25 t VC/ha, and T7: 50% RDF NPK (40 - 15-25 kg/ha). Different agronomic parameters were measured at the intervals of 30, 60, 90, and 120 days after sowing of seeds. All the treatments of vermicompost showed better responses in agronomic parameters than the control treatment. Among them, T5 treatment tends to show significantly (p<0.05) higher plant height (18.5 cm), number of the leaf (54/plant), root length (15.50 cm), first flowering (at 61 days), fruit length (5.75 cm), fruit diameter (13.75 cm), number of fruits (15/plant), the average weight of fruit (14.50 g), the fresh yield of fruits (13.59 t/ha), fresh weight of root (10.41 g/plant), fresh weight of reproductive structure (3.12 g/plant), weight of the dry reproductive structure (3.12 g/plant) and benefit-cost ratio (9.37). T6 treatment showed significantly (p<0.05) higher leaf area (49.00 cm2), fresh weight of petiole (4,61 g/plant), the weight of dry root (2.20 g/plant), weight of dry leaf (5.87 g/plant), weight of dry petiole (1.42 g/plant) and weight of dry biomass (12.48 g/plant). T2, T3 and T4 treatments showed significantly (p<0.05) higher growth than T7 treatment. The overall findings revealed that the application of vermicompost (20 t/ha) in the strawberry plant might be a suitable method in rooftop gardening to achieve its better agronomic and yield parameters in the southern parts of Bangladesh. Dhaka Univ. J. Biol. Sci. 30(2): 283-292, 2021 (July)

A field experiment was carried out in the research farm of Charfasson Govt. College, Bhola during Rabi season in 2016-2017 to evaluate the effects of poultry litter (PL) compost and NPK fertilizers on growth and yield of sunflower cv. BARI-2 (Keroni-2). Sixteen treatments were used with three replications each. Treatments were T1 : Control (-PL and –NPK), T2 : 1.5 ton PL/ha, T3 : 3.0 ton PL/ha, T4 : 4.5 ton PL/ha, T5 : N40P30K50 kg/ha, T6 : N80P60K100 kg/ha, T7 : N120P90K150 kg/ha, T8 : 1.5ton PL/ha + N40P30K50 kg/ha, T9 : 1.5 ton PL/ha + N80P60K100 kg/ha, T10 : 1.5 ton PL/ha + N120P90K150 kg/ha, T11 : 3.0 ton PL/ha +N40P30K50 kg/ha, T12 : 3.0 ton PL/ha + N80P60K100 kg/ha, T13 : 3.0 ton PL/ha + N120P90K150 kg/ha, T14 : 4.5 ton PL/ha + N40P30K50 kg/ha, T15 : 4.5 ton PL/ha + N80P60K100 kg/ha and T16 : 4.5 ton PL/ha + N120P90K150 kg/ha. Plant height (204.3 cm), number of leaf (44.8/plant), leaf area (376.4 cm2/plant), leaf area index (13.61), dry weight of stem (61.57 g/plant), root (12.66 g/plant), leaf (21.47 g/plant), petiole (8.7 g/plant), total dry matter production (134.0 g/plant) were found highest in T16 treatment. On the contrary, dry weight of inflorescence (32.6 g/plant), dry weight of seed (44.4 g/plant) and number of seeds (663/plant) were found highest in T13 and T14 treatments, respectively. Higher dry weight of 100 seeds (7.4 g) and diameter of inflorescence (54 cm) were also found in T13 treatment. Although highest value was found in T16 treatment, but T16 and T13 were not significantly (p > 0.05) different, it can be treated as best (T13) for future trial. The overall findings of this study indicated that organic fertilizer (poultry litter) in combination with inorganic fertilizers may be a good indicator to achieve better agronomic and yield parameters of sunflower plants under southern coastal edaphic conditions of Bangladesh. Dhaka Univ. J. Biol. Sci. 30(1): 49-57, 2021 (January)

Wetland basin soils are the major store houses of organic carbon where there is a scope to use this carbon in mitigating the climate change. A study was conducted in these basin soils at 100 cm depth regarding their carbon stock. The study showed that total soil organic carbon (SOC) stock in the Sylhet basin soils of Bangladesh is 0.094 Pg where the SOC stock was 0.044 Pg in medium low land sites and it was about 0.050 Pg in lowland sites. There was no previous study on SOC stock in the Sylhet basin soils of Bangladesh. These may act as benchmark SOC stock datasets for the future agricultural planning. The soil organic carbon stock is higher in the lowland than medium lowland sites. The contents of SOC are low is compared to its threshold levels. Moreover, it is apprehended that basin soils may lose their carbon due to the decrease of inundation level by climate change, and other eco-environmental changes. So, it is very much urgent to take steps in preserving the organic carbon of lowland basin soils. Asiat. Soc. Bangladesh, Sci. 46(1): 49-60, June 2020