Sirajul Hoque

Long-Term Effects of Tillage on Physicochemical Properties of Modified Andisol of Northeast Honshu Island

Many reports suggest that tillage practices affect crop growth by altering soil properties. However, there is a paucity of information on long-term effects of tillage practices on the properties of modified Andisol in colder region. This study compared the effects of zero tillage (NTg) with continuous fodder crop, zero tillage (NTa) with continuous orchard, conventional tillage (CT) with sweet potato and corn (in summer), and wheat, barley, rye and colza (in winter), and puddling (P) with continuous rice on some selected physical and chemical properties of sandy clay pumice Andisol of colder climate. Mean dry bulk density was 0.92 Mg m−3 for CT, compared with 1.14 Mg m−3 for NTg, 1.16 Mg m−3 for NTa and 1.21 Mg m−3 for P. Total porosity was 63.75% for CT, compared with 55.16% for NTg, 53.72% for NTa and 52.24% for P. Highest content of organic matter (OM) was found in NT compared to other practices. On the other hand, soil pH and electrical conductivity (EC) were significantly lower under NT than other practices. The tillage had significant effects on soil hardness at different matric suction. Gaseous phase was greatest in CT soils, compared with NTa soils, and P soils. Mean solid phase was 44.84%, 45.29%, 47.46% and 36.25%, while liquid phase was 45.50%, 46.06%, 51.21% and 31.65% under NTg, NTa, P, and CT, respectively. Conventional tillage held highest moisture at 0 pF. On the other hand, puddled soil showed highest moisture retention capacities between 1.5 and 7.0 pF than zero tillage and conventional tillage. Gravitational water (GW) and gravitational capillary water (GCW) contents was highest while capillary water (CW), shrinkage water (SW) and hygroscopic water (HW) contents were lowest under CT. Gravitational drainage (GD) and non-easily available water (NEAW) were significantly lowest and easily available water (EAW), total available water (TAW) and non-available water (NAW) were significantly highest under puddling condition compared to other tillage systems. Highest content of boron (B) was found in NT compared to other practices. On the other hand, sulfur (S) and manganese (Mn) were significantly lowest under NT than other practices. Tillage practices had no significant effect on zinc (Zn) content. Compared with CT and P, the use of NT may result in soils having different soil physical and chemical properties, because the soil matrix undergoes fewer disturbances with NT.

Phosphate sorption in some representative soils of Bangladesh

An experiment was conducted to observe the phosphate sorption potential of some soils of Bangladesh. Three soil series of calcareous origin, namely Sara (Aquic Eutrochrept), Gopalpur (Aquic Eutrochrept) and Ishurdi (Aeric Haplaquept), and two soil series of non-calcareous origin, namely Tejgaon (Rhodic Paleustult) and Ghatail (Aeric Haplaquept), were selected. The soils were equilibrated with dilute solution of calcium chloride containing graded concentrations of phosphate (0, 1, 2, 5, 10, 25 and 50 μg P mL−1), and the amount of phosphate sorbed or desorbed was determined. Although all the soils showed potential for sorbing phosphate from applied phosphorus, their ability to sorb phosphorus differed. Increasing rates of phosphate application increased the amount of P sorption but reduced phosphate sorption percentage in all soils except Tejgaon. Phosphate was sorbed by the soils in the order: Tejgaon > Ghatail > Ishurdi > Gopalpur > Sara at 50 μg P mL−1 application. Soils possessing higher amounts of free iron oxide and clay sorbed more phosphate from applied phosphorus.

Emergence of two novel sublineages Ind2001BD1 and Ind2001BD2 of foot-and-mouth disease virus serotype O in Bangladesh

Foot-and-mouth disease (FMD) is endemic in Bangladesh, and the implementation of a control programme for this disease is at an early stage, according to the FAO- and OIE-proposed Progressive Control Pathway for FMD (PCP-FMD) Roadmap. To develop an effective control programme, understanding of foot-and-mouth disease virus (FMDV) serotypes, even subtypes within the serotypes is essential. The present investigation aims at viral VP1 coding region sequence-based analysis of FMD samples collected from 34 FMD outbreaks during 2012-2016 in Bangladesh. Foot-and-mouth disease virus (FMDV) serotype O was responsible for 82% of the outbreaks in Bangladesh, showing its dominance over serotype A and Asia1. The VP1 phylogeny revealed the emergence of two novel sublineages of serotype O, named as Ind2001BD1 and Ind2001BD2, within the Ind2001 lineage along with the circulation of Ind2001d sublineage in Bangladesh, which was further supported by the multidimensional scaling with distinct clusters for each sublineage. The novel sublineages had evident genetic variability with other established sublineages within Ind2001 lineage. Ten mutations with three or more amino acid variations were detected within B-C loop, G-H loop and C-terminal region of the VP1 protein of FMDV serotype O viruses isolated exclusively from Bangladesh. Furthermore, two amino acid substitutions at positions 197 and 198 within the VP1 C-terminal region are unique to the novel sublineages. The existence of widespread genetic variations among circulatory FMDV serotype O viruses makes the FMD control programme complex in Bangladesh. Adequate epidemiological data, disease reporting, animal movement control, appropriate vaccination and above all stringent policies of the government are necessary to combat FMD in Bangladesh.

Assessing Surface Water Quality Using Landsat TM and In Situ Data: An Exploratory Analysis

The objective of this chapter was to explore the potential of Landsat TM data, calibrated by in situ measurements, to map the spatial distribution of water quality in the rivers and lakes of Dhaka. The relationship of satellite brightness values and ground measurement was established through correlation and regression analyses. The results showed that the ratio of TM1 and TM3 was highly correlated with Secchi disk transparency (SDT), a measure of water clarity, while total suspended sediment (TSS) was strongly correlated with brightness values in the near-infrared portion of the electromagnetic spectrum. Regression analysis indicated that TM1 and the ratio of TM1/TM3 was the best predictor for SDT, and TM3 and the ratio of TM1 and TM3 was suitable for the estimation of TSS in waters. Maps of SDT and TSS are presented that illustrate the spatial variation of water quality in the inland water systems of Dhaka.