The challenge the researchers set out to address is both local and global. Coastal Bangladesh is dominated by soils that turn saline during the dry season, when seawater intrusion and capillary rise push electrical conductivity in the root zone to between three and four decisiemens per meter, a level classified as slightly saline but still enough to stress young crops. Traditionally, farmers in the region grow a single monsoon rice crop and leave their fields fallow for the rest of the year. Maize has emerged as a promising dry-season crop for these fallow lands, valued for food, feed and biofuel, yet fertilizer guidelines for the region remain rudimentary. Farmers commonly broadcast urea without regard to timing, placement or the crop’s actual demand, wasting money and losing nutrients to the environment.

Nitrogen is the engine of maize productivity, but it is also the most easily lost nutrient. Applied too early, urea sits in soil that the young crop barely taps during its first month of growth, when uptake is minimal. In warm, moist, salinity-affected soils, that idle nitrogen is vulnerable to ammonia volatilization, leaching and the ionic imbalances that salinity imposes on roots. The research team framed their experiment around the 4R nutrient stewardship framework, the right source, right rate, right time and right place, focusing on the two dimensions most neglected in coastal practice: timing and placement. Their question was whether synchronizing nitrogen supply with the crop’s rapid vegetative and reproductive growth phases could recover the yield potential that indiscriminate broadcasting squanders.

The trial was laid out as a randomized complete block design with seven treatments and three replications, all receiving the same total nitrogen rate of 225 kilograms per hectare, alongside uniform phosphorus and potassium. The treatments varied the schedule and method of delivery: some placed a third of the nitrogen at sowing by broadcasting, side banding or row placement before two later side dressings; others delayed or reshuffled the splits entirely. One treatment applied 20 percent of the nitrogen at fifteen days after sowing followed by 40 percent at each of the later dates, while others applied half the nitrogen at 35 days, or the entire dose in a single side dressing at 35 days. The test crop was the hybrid DON 111, a medium-duration variety with a yield potential of 12 to 13 tonnes per hectare under good management.

The winner was unambiguous. Applying nitrogen in three equal side-dressed splits at 15, 35 and 60 days after sowing produced the highest grain yield in every season: 10.87 tonnes per hectare in 2022, 11.76 in 2023 and 10.79 in 2024, all statistically significant at the one percent level. The pooled stover yield of 11.78 tonnes per hectare and root yield of 1.44 tonnes per hectare were also highest under this schedule. By contrast, the treatment that placed a third of the nitrogen directly in the seed furrow at planting recorded the lowest yields, a result the researchers attribute to urea’s close contact with seeds, which hampered germination and produced an uneven plant population. The conventional farmer practice of basal broadcasting followed by two side dressings fell well short of the delayed-split strategy.

The physiological story behind the yield gap is revealing. Side-dressed nitrogen delivered near the plant rows maintained an adequate supply through the later growth stages, extending the active life of green leaves and sustaining the accumulation of photosynthetic assimilates during grain filling. The delayed-split treatment produced the longest cobs, the most grains per cob, reaching 620 grains on pooled data, and the heaviest thousand-grain weight at 217 grams. Correlation analysis underscored how these components stack up: thousand-grain weight showed the strongest association with grain yield, with a correlation coefficient of 0.79, while root yield correlated at 0.77, suggesting that a well-fed root system underpins the whole yield architecture. Cob length and grain number per cob were likewise tightly linked to final yield.

Root development deserves particular attention in saline soils, where osmotic stress makes water and nutrient acquisition harder. The three-split side-dressing schedule produced the highest root yields in 2022 and 2023, and the pooled root yield advantage was highly significant. The researchers argue that delaying the first application until active root establishment improves the synchronization between nitrogen availability and crop uptake, which in turn enhances nitrogen use efficiency. Adequate nitrogen supports healthy root architecture, and a denser root system improves the plant’s capacity to buffer the salt-induced nutrient imbalances that characterize coastal soils in March and April, when conductivity peaks just as the crop approaches maturity.

The economics reinforce the agronomy. Compared with the farmer practice of basal broadcasting, the optimized schedule added 860 kilograms of grain per hectare on pooled yields, worth roughly 287 US dollars at local grain prices. The only extra cost was labor for the additional first side dressing at fifteen days, about 15 dollars per hectare for two extra workers. That leaves a net gain of more than 270 dollars per hectare from a change that requires no new inputs, no new varieties and no machinery, only a shift in when and where existing fertilizer is applied. For smallholders in one of the world’s most densely populated and climate-vulnerable deltas, that margin could determine whether dry-season maize is worth planting at all.

The findings also carry environmental weight. Nitrogen that is not captured by the crop does not simply vanish; it can escape as ammonia gas, leach into groundwater, or be transformed into nitrous oxide, a greenhouse gas nearly 300 times more potent than carbon dioxide. Previous work cited by the team shows that interactions between salinity and fertilizer type significantly shape ammonia and nitrous oxide fluxes, meaning that mismanaged nitrogen in coastal soils is doubly wasteful. By matching supply to demand, the delayed-split approach minimizes these losses while maintaining nutrient availability during the critical vegetative and reproductive phases. The authors note that their results align with the 4R stewardship principles and with earlier studies showing that split applications extend leaf greenness beyond anthesis in stay-green maize hybrids.

Caveats remain, as they always do. The trial was conducted on a single soil series, a silty clay loam of the Ramgoti series, at one site near the Bay of Bengal, and the 2023 season benefited from warmer vegetative-stage temperatures and some rainfall during grain filling. Salinity dynamics vary across the coastal zone, and recommendations will need validation across a wider range of soils and weather patterns. Still, the core insight travels well beyond Bangladesh: in seasonally saline environments, the cheapest yield gain available to farmers may lie not in more fertilizer but in better-timed fertilizer. As maize expands into the fallow lands of coastal deltas worldwide, the humble act of waiting two weeks before the first urea application could reshape the economics of farming at the salty edge of agriculture.

Subject of Research: Optimizing the timing and placement of split nitrogen fertilizer application to improve maize yield and nitrogen use efficiency in slightly saline coastal soils of Bangladesh.

Article Title: Optimizing split nitrogen application for enhanced maize yield in slightly saline coastal soils (ECe 3–4 dS m−1)

Article References: Haque, M. A., Bhuyan, M. I., Jharna, D. E., Jahiruddin, M., & Bell, R. W. (2026). Optimizing split nitrogen application for enhanced maize yield in slightly saline coastal soils (ECe 3–4 dS m−1). Discover Soil, 3(1), Article 123. https://doi.org/10.1007/s44378-026-00282-1

Image Credits: AI Generated

DOI: 10.1007/s44378-026-00282-1

Keywords: maize, nitrogen fertilizer, split application, side dressing, soil salinity, coastal agriculture, Bangladesh, Ganges delta, nitrogen use efficiency, 4R nutrient stewardship, grain yield, fertilizer timing

The tool at the heart of the study is the Modified Geosite Assessment Model, or M-GAM, a quantitative method that evaluates geosites on two complementary dimensions. The Main Value (MV) captures intrinsic scientific and educational qualities: how representative a landform is of regional geomorphic processes, how rare it is, how well it records geological history, and how intact it remains. The Additional Value (AV) covers the practical and experiential attributes that determine whether a site can actually attract and serve visitors: accessibility, infrastructure, scenery, safety, and the presence of interpretive facilities. By separating what a site means from what a site offers, the model prevents spectacular but remote landforms from being judged by the same criteria as accessible viewpoints, and vice versa.

What distinguishes this application from earlier uses of the model is its dual-audience design. Experts scored each geosite on 27 standardized sub-indicators, but the researchers then modified those expert judgments with importance factors (Im) derived from visitors themselves. A structured survey collected opinions from 202 respondents, whose ratings of how much weight each attribute deserved were folded into the expert assessment. This is a meaningful methodological refinement: geotourism planning often fails because scientists and tourists value different things, and a ranking that ignores visitor priorities risks protecting sites nobody visits while promoting sites with little scientific substance. The visitor survey instrument showed acceptable internal consistency, with Cronbach’s alpha of 0.79 for the Main Value subscale and 0.84 for the Additional Value subscale, indicating that respondents answered in a coherent and reliable pattern.

The results reveal striking variability across the state’s inventory. Scores differed widely on all five attribute clusters the authors examined: scientific and educational value, scenic and aesthetic appeal, protection status, functional capacity, and touristic potential. Perhaps the most telling headline number is the comparison of the two value dimensions. The mean Additional Value score across the 42 geosites was 11.90, notably higher than the mean Main Value score of 8.53. In plain terms, the sites of West Bengal, on average, offer better functional and tourism-supporting conditions than their intrinsic scientific scores alone would suggest, and those practical attributes pull substantial weight in the final relative rankings. For planners, this means that infrastructure and access, not just geological significance, drive which sites rise to the top.

Using quartile-based thresholds within the study inventory, the team sorted the 42 geosites into three priority classes: 13 sites of relatively high priority, 18 of moderate priority, and 11 of low priority. This relative classification is deliberately comparative rather than absolute; a site’s rank depends on how it performs against the other sites in the same dataset, which makes the method well suited to allocating limited conservation and promotion budgets across a state-wide portfolio. The high-priority group represents the landscapes where scientific value, visitor experience and management readiness converge, and where investment in geotourism is most likely to pay both educational and economic dividends.

Correlation analysis of the model’s components added quantitative texture to these patterns. Accessibility correlated strongly with visitor numbers (r = 0.74), a relationship that will surprise no one who has watched a well-paved viewpoint outdraw a more remarkable but unreachable landform. The correlation between the touristic component and Additional Value was even stronger (r = 0.81), but the authors treat this figure with appropriate caution, because the touristic component is itself part of the Additional Value construct, making the association partly circular. This kind of statistical self-awareness is a strength of the paper: rather than presenting every correlation as a discovery, the authors flag which relationships are independent evidence and which are artifacts of how the model is built.

One of the most interesting analytical moves in the study is the direct comparison of expert and visitor assessments, which identifies sites where geomorphological significance and perceived importance either converge or diverge. Convergence suggests a site where scientific merit and public appeal reinforce each other, the ideal profile for flagship geotourism destinations. Divergence cuts both ways: some sites of genuine scientific importance score poorly with visitors, often because they lack the scenery, access or interpretation that makes geomorphology legible to non-specialists, while other visually spectacular sites may attract crowds without carrying exceptional scientific weight. Mapping these convergences and divergences gives managers a practical triage tool, showing where investment in trails, signage and interpretation could close the gap between what a landform is and what visitors think it is.

The geographic sweep of the inventory is itself a contribution. Geosite assessments have often focused on single provinces, a mountain range or a coastline, evaluated in isolation. By sampling across the Himalaya, the Sub-Himalayan piedmont, the plateau, the fluvial plains, the delta and the coast within one consistent framework, the study makes it possible to ask, for the first time in this region, which landscape types deliver the highest combined value. That matters for a state whose geomorphic identity is defined by this extraordinary gradient, and it matters for geotourism strategies that could link sites into itineraries tracing the full descent from high mountains to the sea.

The authors are candid about the uncertainties inherent in the approach. Visitor sampling may not represent the full population of potential tourists; expert scoring involves judgment calls; the weighting and aggregation of sub-indicators embed assumptions; and the quartile-based classification is relative, meaning a different inventory could reshuffle the ranks. None of these caveats undermines the core contribution, which is to demonstrate M-GAM as a comparative decision-support framework. The study was approved by the Institutional Ethics Committee of the Department of Geography at Syamaprasad College, conducted in accordance with the Declaration of Helsinki, and carried out with informed consent from all survey participants. The authors declare no competing interests, and the work received no external funding.

Published as an open-access article on 30 September 2026, the paper arrives at a moment when geotourism is gaining traction as a sustainable alternative to mass tourism in ecologically sensitive regions. For West Bengal, the practical implications are concrete: the 13 high-priority geosites form a ready-made shortlist for infrastructure investment, interpretation programs and heritage designation, while the divergent sites identified through the expert-visitor comparison point to where low-cost interventions such as signage and access improvements could unlock hidden value. More broadly, the study offers a template that other geomorphologically diverse regions, from Andean valleys to Rift Valley escarpments, could adapt. By putting numbers on the sometimes vague language of geoheritage, and by insisting that visitors have a formal voice in how landforms are valued, the research moves geosite assessment from description toward decision, and gives the landscapes of West Bengal a quantified case for the protection and promotion they have long deserved.

Subject of Research: Quantitative assessment and prioritization of geomorphosites for geotourism and geoheritage conservation in West Bengal, India

Article Title: Geomorphosite assessment and prioritization across diverse landscapes of West Bengal India using expert and visitor modified geosite assessment model

Article References: Bhandari, U., Mondal, S., Basak, I., Roy, M., Koley, B., Das, S., & Nath, A. (2026). Geomorphosite assessment and prioritization across diverse landscapes of West Bengal India using expert and visitor modified geosite assessment model. Discover Sustainability. https://doi.org/10.1007/s43621-026-04880-5

Image Credits: AI Generated

DOI: 10.1007/s43621-026-04880-5

Keywords: geomorphosites, geosites, geoheritage, geodiversity, geotourism, M-GAM, West Bengal, Eastern Himalaya, Ganges Delta, sustainable tourism, site assessment, geomorphology