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 study matters because nitrogen is the engine of corn production. The nutrient sits at the center of photosynthesis, protein synthesis, and biomass accumulation, and Maritime provincial recommendations call for roughly 115 to 150 kilograms of nitrogen per hectare to reach economically viable yields. Yet corn typically recovers only a fraction of what is applied. Losses occur through ammonia volatilization, nitrate leaching, denitrification, nitrification, and surface runoff, eroding nitrogen use efficiency, inflating production costs, and raising environmental concerns. Enhanced-efficiency fertilizers were designed to close that gap by slowing the transformation or release of nitrogen in soil, ideally synchronizing availability with the crop’s uptake curve.

The two products tested work by fundamentally different mechanisms. Polymer-coated controlled-release urea relies on a physical barrier whose permeability changes with soil temperature and moisture, metering out nitrogen over weeks or months. Stabilized fertilizers, by contrast, use chemistry rather than coatings: SuperU contains N-(n-butyl) thiophosphoric triamide to slow urea hydrolysis and dicyandiamide to inhibit nitrification, the microbial conversion of ammonium to nitrate, which is the form most vulnerable to leaching. Whether either strategy pays off, however, depends heavily on environment, and Atlantic Canada presents a distinctive one: a short growing season, cool spring soils that slow both crop uptake and soil microbial activity, and precipitation patterns that swing widely from year to year.

The experimental design was deliberately practical. Fifteen fertilizer treatments were arranged in randomized complete block designs at Truro, Nova Scotia in 2024 and at the Agriculture and Agri-Food Canada Research Station in Harrington, Prince Edward Island in 2024 and 2025. Treatments spanned conventional urea, both enhanced-efficiency products, single versus split applications, nitrogen rates of 75, 100, 125, and 150 kilograms per hectare, and one-to-one blends of each specialty product with uncoated urea. The researchers measured grain yield at 15.5 percent moisture, test weight, hundred kernel weight, harvest index, agronomic efficiency, partial factor productivity, and a partial return on investment calculated against fertilizer cost alone.

When the data were combined across site-years, fertilizer source, application timing, and their interaction showed no significant effect on grain yield at the standard 125-kilogram rate. The story sharpened only when results were parsed by site. At Harrington in 2024, splitting nitrogen between planting and roughly the six-leaf stage lifted yield to 9.31 tonnes per hectare from 8.43 tonnes for a single application, and also raised agronomic efficiency from 27.6 to 34.6 kilograms of grain per kilogram of nitrogen applied. But that advantage vanished at the other site-years. Notably, the split benefit appeared in the year with the driest May and June, hinting that early-season rainfall patterns, not fertilizer chemistry, may govern whether a second pass with the spreader is worth the diesel.

The reduced-rate hypothesis fared no better as a general rule. The researchers asked whether enhanced-efficiency products could maintain yield at lower nitrogen rates, an idea supported by earlier work in northeastern Australia where inhibitor-treated fertilizer performed as well as urea with ten kilograms less nitrogen. Here, the answer was stubbornly site-specific. At Truro in 2024, where a prior manure application and a soybean rotation had built substantial residual fertility, the unfertilized control itself yielded a remarkable 7.40 tonnes per hectare, muting differences among all fertilized treatments. At Harrington in 2025, a much drier year in which growing-season precipitation fell to 299.7 millimeters and August delivered just 12.2, yields dropped roughly 30 percent and SuperU outperformed the polymer-coated product on yield, test weight, and efficiency metrics, with higher nitrogen rates generally winning. The authors caution that without direct measurements of soil moisture or nitrogen fluxes, the mechanism behind that product difference cannot be pinned down.

Perhaps the most commercially intriguing result concerned blending. Mixing the expensive specialty products half-and-half with ordinary urea, matched by nitrogen content, produced no significant yield, quality, or efficiency penalty relative to full-rate enhanced-efficiency treatments at any site-year. Under the assumed prices, with urea at CAD $839 per tonne, SuperU at $1,386, and PurYield at $1,288, blending cut fertilizer costs by roughly CAD $65 to $74 per hectare. A break-even analysis showed those savings could absorb a yield reduction of about 0.22 to 0.25 tonnes per hectare before the economics turned negative. Since the blends showed no measurable yield penalty, the strategy looks like a low-risk entry point for producers hesitant to commit fully to premium fertilizers, though the authors stress the thresholds shift with any change in fertilizer or grain prices.

The economic analysis also revealed how much background soil fertility shapes the payoff from any nitrogen strategy. At Truro, partial returns on investment did not differ significantly among treatments, a consequence of the site’s high native nitrogen supply. At Harrington, where crops depended more heavily on applied nitrogen, fertilizer treatment strongly influenced returns in both years, with the unfertilized control and single applications of plain urea generally faring worst. Intriguingly, the highest 150-kilogram rate did not consistently improve returns, suggesting that choosing the right rate for the field matters more than choosing the flashiest product.

Grain quality told a subtler story. Test weight, a proxy for kernel density, responded to fertilizer management at the Harrington site-years, with the highest values in split-applied treatments and high-rate SuperU, while hundred kernel weight remained essentially flat everywhere. That pattern implies nitrogen availability during grain filling influences how densely kernels pack rather than how large they grow, consistent with earlier maize research showing nitrogen supply affects grain filling and protein accumulation more than kernel size.

The overarching lesson is one of humility toward one-size-fits-all fertilizer marketing. Site-year accounted for 71 to 96 percent of the total variance across response variables, dwarfing treatment effects. Enhanced-efficiency fertilizers, the authors conclude, are best viewed as components of an integrated nitrogen management system rather than stand-alone yield boosters. In Atlantic Canada’s humid, variable Maritime climate, their value may lie in expanding the menu of management options, particularly through cost-saving blends, rather than in delivering guaranteed harvest gains. For farmers, the calculus remains local: soil history, rainfall, and price spreads, not product labels, should drive the decision.

Subject of Research: Agronomic and economic performance of enhanced-efficiency nitrogen fertilizers in Atlantic Canadian grain corn production

Article Title: Grain corn response to enhanced-efficiency nitrogen fertilizers under different rates, timings, and blending strategies in Atlantic Canada

Article References: Lynds, B., MacEachern, D., McLean, N., Lumactud, R., Smith, E., & Jiang, Y. (2026). Grain corn response to enhanced-efficiency nitrogen fertilizers under different rates, timings, and blending strategies in Atlantic Canada. Journal of Agriculture and Food Research, 31, Article 103313. https://doi.org/10.1016/j.jafr.2026.103313

Image Credits: AI Generated

DOI: 10.1016/j.jafr.2026.103313

Keywords: grain corn, nitrogen fertilizer, enhanced-efficiency fertilizers, controlled-release urea, nitrification inhibitors, split application, nitrogen use efficiency, Atlantic Canada, 4R nutrient stewardship, fertilizer blending, agronomic efficiency, return on investment