Bangladesh Rice Research Institute

Much of the Ganges’ coastal region remains fallow during the dry (Rabi) season due to the unavailability of freshwater, soil and water salinity, and inadequately tested irrigation strategies. Therefore, the aims of this research were: (i) to assess the effectiveness of irrigation with brackish water for crop yield, water use, and water productivity (WP), (ii) to analyze how irrigation affects soil solute potential (SP) during the growing season and its implications for crop growth. Two field experiments tested four irrigation treatments (T1-one irrigation at crown root initiation (CRI) stage, T2-two irrigations at CRI and booting, T3-two irrigations at CRI and grain development, T4-three irrigations at CRI, booting, and grain development) with three replications on wheat and barley in 2018–2019 and 2019–2020 in two locations (Dacope and Amtali) in the coastal region of the Ganges delta. The brackish water (≤ 4 dSm-1) irrigation had a significant effect on wheat and barley yields. When irrigation water was provided at later growth phases of wheat, treatment T4 produced highest yield of 2.5 tha− 1 at Amtali and 1.7 tha− 1 at Dacope. In both locations, barley grain yield significantly increased with each additional irrigation. WP of wheat and barley under different irrigation regimes varied with an average of 0.9 and 1.5 kgm− 3 at Dacope and 1.5 and 1 kgm− 3 at Amtali, and 1.1 and 1.6 kgm− 3 at Dacope and 1.6 and 1 kgm− 3 at Amtali in 2019 and 2020, respectively. Irrigation had significant effect on WP, and increased SP as well as yield in both locations and years. SP rose as soil dryness decreased and vice versa. In February-March SP was significantly lower in the upper soil depths. Two or three irrigations with brackish water may be useful for increasing cropping intensity and WP of wheat and barley with a little yield reduction in the Ganges delta.

Abstract Rice-based cropping systems remain dominant in Bangladesh’s agricultural landscape, yet their long-term sustainability and profitability are increasingly constrained by high input requirements, ecological pressures, and evolving food consumption patterns. This study investigates the agronomic and economic performance of four rice-based farming sequences in the Karatoa–Bangali Floodplain, comparing the conventional T. Aman–Fallow–Boro (R–F–R) rotation with three diversified alternatives: Mustard–Mungbean–T. Aus–T. Aman (M–M–R–R), Potato–Maize–Dhaincha–T. Aman (P–M–D–R), and Potato–Sweet gourd–Jute–T. Aman (P–S–J–R). Field experiments conducted during 2021–2022 evaluated system productivity, profitability, land use efficiency (LUE), and sustainability indicators such as marginal benefit–cost ratio (MBCR), sustainable yield index (SYI), and rice equivalent yield (REY). The results showed that the gross return, benefit–cost ratios (BCR), LUE, and production efficiency (PE) of all intensified cropping systems significantly outperformed the baseline pattern (R–F–R). Among them, P–S–J–R sequence demonstrated the highest REY (31.81 t/ha), SYI (98.97%), and MBCR (2.75), highlighting its strong agronomic and economic potential. The integration of short-duration rice cultivars and high-value non-rice crops facilitated more efficient land utilization—up to 94%—and enabled continuous year-round cultivation. These findings underscore the value of strategic crop diversification and intensification, particularly through the use of short-duration varieties and relay cropping, in enhancing system resilience, resource optimization, and farm-level income in rice-centric regions. Scaling up such cropping systems, with support from policy and research initiatives, could foster more sustainable and climate-adaptive agricultural systems across the Indo-Gangetic Plains.

Rapid urbanization and climate change are intensifying outdoor heat stress in tropical megacities, yet most urban heat assessments rely on air temperature or land surface temperature (LST) metrics that do not directly represent physiological thermal strain. This study presents a high-resolution (100 m) spatial characterization of heat stress in Dhaka, Bangladesh, using Wet Bulb Globe Temperature (WBGT) derived from the UrbClim urban climate model for 2008-2017. Daily minimum (WBGTmin), mean (WBGTmean), and maximum (WBGTmax) values were analyzed and classified according to internationally recognized occupational heat-stress thresholds. Results reveal substantial intra-urban variation in heat exposure, with central and northern wards-including Tejgaon, Motijheel, Mirpur, Pallabi, Uttara, and Kafrul-experiencing persistently elevated thermal risk. Monthly WBGTmax peaked in May (similar to 34.6 degrees C) and reached its minimum in January (similar to 22.2 degrees C), while WBGTmin was highest in July (similar to 26.9 degrees C) and lowest in January (similar to 13.9 degrees C), indicating pronounced seasonal contrasts in diurnal thermal exposure. WBGTmax exceeded the "extreme" occupational stress threshold (>32.2 degrees C) on 56 to 78 days annually in multiple wards during the pre-monsoon and monsoon seasons, with spatial patterns of exceedance showing strong consistency across years. Given the 10-year observational period, this study focuses primarily on characterizing persistent spatial patterns and seasonal dynamics of heat stress exposure rather than establishing long-term climatic trends. By applying a physiologically grounded heat-stress index at neighborhood scale, this research provides actionable spatial intelligence for climate-responsive urban planning, occupational safety regulation, and targeted heat-adaptation strategies in Dhaka and other rapidly growing tropical megacities.

Continuous rice cropping using organic and inorganic fertilizers might affect greenhouse gas emissions and their balance, rice yield, and soil aggregate stability, as investigated at the experimental farm of Bangladesh Rice Research Institute. The influence of vermicompost (VC) rates with chemical fertilizers on greenhouse gas (GHG) emission, GHG intensity, emission factor, and rice yields was evaluated in a Boro (January-May)-Fallow-T. Aman (July-November) cropping system. The static close chamber technique estimated methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2). Total CH4, N2O, CO2 flux, net carbon emission (NCE), GHG intensity, and GHG emission factors (EFs) were significantly lower with 0.5 t ha− 1 VC + recommended chemical fertilizers (RCF) dose and reduced about 28–29

This study explores crop diversification (CD) in smallholder farming systems in the coastal zone of the Ganges Delta in southern Bangladesh, which faces significant environmental challenges such as drought, erratic rainfall, soil salinity, waterlogging, and cyclones. These factors undermine agricultural sustainability and contribute to poverty and food insecurity. This research examines how environmental, farm resource, and socioeconomic factors influence CD across 200 farms in the Barguna, Khulna, and Patuakhali districts of Bangladesh. The Herfindahl index was used to measure crop diversity, showing an average value of 0.36, indicating moderate concentration and relatively high diversity, although half of the farmers exhibited higher values. The Fractional Probit model findings show that environmental factors such as reduced waterlogging and soil salinity positively influenced CD, while farm resources like access to irrigation, number of land parcels, and access to machinery facilitated greater diversity. Socioeconomic factors, such as greater distance from markets and the availability of hired labour, also promoted CD, but seasonal migration of the household head and low household savings hindered it. The study found that Khulna exhibited greater CD, while tidal flooding limited agricultural potential in Patuakhali district . The study recommends improving environmental and socioeconomic conditions in Bangladesh’s coastal farming systems through targeted soil rehabilitation, drainage and irrigation, expansion of water infrastructure and harvesting solutions, and improving access to affordable mechanisation. Strengthening rural infrastructure and financial tools, such as crop insurance and low-interest loans, will enhance resilience, farm incomes, and long-term sustainability. Tailored strategies are recommended for the Khulna and Patuakhali districts to support region-specific cropping systems and diversification.