A farm on an island in the Ganges delta, Sundarban area (Credit: Arne Hückelheim)
Across the coastal landscapes of the Sundarbans delta, water shapes every aspect of farming. Too much water after the monsoon leaves fields waterlogged, while too little fresh water during the dry season allows salt to accumulate in soils. For decades, this combination of waterlogging and salinity has restricted cultivation across large areas of coastal Bengal, leaving many fields uncultivated during the Rabi season.
Yet a new study published in Agricultural Systems suggests that these constraints may not be permanent. By combining improved water management with carefully timed agricultural practices, researchers have identified pathways that can restore dry season crop production in some of South Asia’s most vulnerable coastal farming landscapes.
The study, “Achieving the once-unthinkable: Successful Rabi cropping via technology integration in coastal saline Bengal", led by researchers including Donald S. Gaydon and Sukamal Sarkar, combines field experiments with advanced crop modelling to assess how farmers can manage salinity, waterlogging and climate risks simultaneously. The findings point to the importance of treating water management, crop selection and soil health as interconnected challenges rather than isolated problems.
Map of the study area (Credit: Donald S. Gaydon et al)
The paper, led by researchers including Donald S. Gaydon and Sukamal Sarkar, is particularly important because it moves beyond isolated field trials. Instead, it combines multi-season experiments with advanced crop modelling using the Agricultural Production Systems Simulator (APSIM), enabling the researchers to simulate 25 years of cropping outcomes under different salinity, rainfall, drainage, and sowing conditions. The result is a scientifically grounded framework for climate-resilient intensification in one of South Asia’s most vulnerable agricultural regions.
Coastal agriculture in Bengal faces multiple water-related challenges. In parts of coastal West Bengal, soil salinity regularly exceeds 4 dS m⁻¹ during the cropping season, significantly affecting crop productivity. At the same time, nearly 30 percent of Bangladesh’s cultivable coastal land experiences monsoon season waterlogging, while around one million hectares are affected by dry season salinity.
Traditionally, many farmers have relied on monsoon-season Aman rice cultivation and left fields fallow during the Rabi season because of the high risks associated with dry-season farming. Several factors contribute to this situation. Long-duration rice varieties delay harvests, fields remain saturated after the monsoon, fresh irrigation water becomes scarce, and salts rise through the soil profile as fields dry. Late sowing further exposes crops to increasingly saline conditions. Together, these factors create a cycle of low cropping intensity, limited income opportunities and greater vulnerability to climate variability.
The once-unthinkable formula: A 4-part integration (Image made using Gemini AI)
What distinguishes this study is its systems approach. Rather than focusing on a single crop or intervention, researchers evaluated different crop sequences involving rice, wheat, maize, sunflower, lentil and grass pea across sites in Bangladesh and West Bengal with varying salinity and hydrological conditions.
The study combined field experiments with simulations using the Agricultural Production Systems Simulator (APSIM), enabling researchers to model 25 years of cropping outcomes under different combinations of rainfall, groundwater conditions, drainage systems, salinity levels and sowing dates. This approach helped identify not only what works in a particular season, but also which strategies remain effective over the long term.
Pillars 1 and 2: Shifting the timeline to escape salt (Image made using Gemini AI)
One of the clearest findings from the study was the importance of sowing crops early. Across almost all crops studied, delayed sowing reduced yields by 25 to 56 percent. Wheat and maize yields declined sharply when sowing occurred after mid-November, while sunflower, lentil and grass pea also experienced significant yield reductions when planting was delayed.
The reason is closely linked to water and salinity dynamics. Early sowing allows crops to use residual soil moisture remaining after the monsoon and complete key growth stages before salinity intensifies during late winter and the pre-monsoon period. Crops planted later face higher evaporation rates, increasing salt accumulation around roots and raising irrigation requirements.
APSIM simulations over a 25-year period showed that groundwater conditions and salinity influenced yield losses more strongly than temperature increases alone. However, the study also highlights an important challenge. Sowing earlier increases exposure to waterlogging because fields may still contain excess moisture immediately after the monsoon. This creates a critical trade-off between avoiding salinity and managing waterlogging.
The study found that successful dry season cultivation depends on integrating four key interventions:
Short duration Kharif rice varieties
Early Rabi sowing
Effective field drainage
Crop residue retention
Researchers emphasise that none of these measures is sufficient on its own. Productivity gains occur when all four are implemented together. Short-duration rice varieties play a particularly important role because they mature earlier than traditional Aman rice, creating a larger planting window for Rabi crops. Earlier harvests reduce exposure to increasing salinity and lower irrigation requirements.
Field drainage is equally important. Surface and subsurface drainage systems help remove excess water after the monsoon and reduce ponding caused by unexpected rainfall events. Previous studies cited in the paper found that integrated drainage systems nearly doubled yields of early-sown Rabi crops under saline conditions. The findings highlight how managing water movement across fields can be as important as managing water availability itself.
The study also identifies crop residue retention as an important adaptation strategy. Across South Asia, crop residues are often removed from fields for fodder or fuel. However, APSIM simulations showed that retaining rice straw reduced soil evaporation, improved soil moisture retention and limited the upward movement of salts.
These benefits became particularly important during periods of drought and salinity stress later in the growing season. The findings add a new dimension to discussions around crop residue management. Beyond reducing air pollution, residue retention may also help farmers manage salinity and improve resilience in coastal agricultural systems.
Pillar 3: Beating the early-waterlogging risk (Image made using Gemini AI)
The study repeatedly stresses that salinity and waterlogging cannot be managed effectively at the level of individual farms alone. Water moves across landscapes through canals, ponds, drainage channels and groundwater systems. As a result, successful adaptation depends on collective action.
The authors argue that community-managed drainage systems, coordinated irrigation schedules and collective responses to extreme weather are essential for expanding Rabi cultivation in coastal regions. This has important governance implications. Coastal resilience depends not only on agricultural interventions but also on coordination among irrigation departments, local governments, agricultural agencies and farmer groups.
(Pillar 4: Mulch as a physical salt shield (Image made using Gemini AI)
The research also advances understanding of how modelling tools can support future agricultural planning. Researchers modified APSIM to account for daily changes in groundwater depth and salinity, enabling more realistic simulations of soil moisture and salt movement. The study proposes linking APSIM with hydrological models such as MODFLOW and FEFLOW to better predict future groundwater behaviour and crop responses under changing climate conditions.
Such integrated systems could eventually support localised decision-making by helping farmers and planners identify suitable sowing dates, crop choices and irrigation strategies based on expected salinity conditions. For coastal regions facing increasing climate uncertainty, this type of water-focused decision support may become increasingly valuable.
The findings offer several lessons for policymakers working on agriculture, water management and climate adaptation. The study highlights opportunities to promote crop diversification beyond rice through wheat, sunflower, maize, lentil and grass pea cultivation under improved management conditions.
It also underscores the importance of investing in drainage infrastructure, supporting residue retention, strengthening community-based water governance and developing localised salinity advisory systems. Importantly, the research suggests that salinity adaptation should not be viewed solely as a protective measure. Better water management can also increase cropping intensity, improve productivity and enhance livelihood opportunities.
The authors acknowledge that APSIM requires further refinement for some crop responses and future climate scenarios. However, they conclude that the framework is already robust enough to inform policy and field-level interventions.
For many years, large parts of the coastal Bengal delta were considered unsuitable for reliable dry season agriculture. Rising salinity, prolonged waterlogging and growing climate uncertainty reinforced the perception that agricultural decline was inevitable. This study presents a different perspective.
Its findings suggest that the future of coastal farming may depend less on overcoming a single challenge and more on managing the interactions between water, soil, crops and climate. Through a combination of improved drainage, timely sowing, short-duration rice varieties and residue retention, farmers can create conditions that support productive dry-season cultivation even in saline environments.
As sea level rise, changing rainfall patterns and salinity intrusion continue to reshape coastal landscapes, the lessons from the Sundarbans highlight the importance of integrated water management. The study shows that restoring agricultural productivity is not simply a question of improving crops. It is also about understanding how water moves through landscapes and using that knowledge to build more resilient farming systems.