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

The research team, led by Kisman Bhattarai and Nithya Rajan of Texas A&M’s Department of Soil and Crop Sciences, conducted field experiments at the university’s research farm near College Station in 2021 and 2022. The site sits on Weswood silty clay loam in a humid subtropical climate, and the region’s rivers ultimately drain into the Gulf of Mexico, where nutrient-driven hypoxia has become a serious ecological concern. Maize in central Texas is grown primarily as a rainfed crop, making the interaction between fertilizer timing and rainfall a matter of both economic and environmental consequence.

The experimental design was thorough. The researchers tested eight different split nitrogen applications in 2021, ranging from applying all nitrogen at planting (a 100:0 split) to dividing it evenly between planting and the R1 silking stage (a 50:50 split). The full fertilizer rate was 240 kilograms of nitrogen per hectare, based on the highest recommended rate for corn in the region. In 2022, they added two reduced-rate treatments—50 percent and 25 percent of the full rate—to see whether cutting nitrogen inputs could maintain yields under stress. All treatments were replicated four times in a randomized complete block design, and the team measured everything from plant height and leaf area index to chlorophyll content, biomass, grain yield, plant nitrogen uptake, and residual soil nitrate at multiple depths down to 60 centimeters.

The two growing seasons could not have been more different, and that contrast turned out to be the study’s greatest asset. In 2021, growing-season precipitation totaled 572 millimeters, above the 20-year average of 508 millimeters, and timely rains coincided with the reproductive stages. In 2022, by stark contrast, only 100 millimeters of rain fell during the growing season—just 20 percent of the long-term average—accompanied by air temperatures one to three degrees Celsius higher than the previous year. The 2022 season was classified as drought-prone, and the results reflected it: average grain yield in fertilized plots collapsed from 11.67 megagrams per hectare in 2021 to 4.09 megagrams per hectare in 2022, a 63 percent decline.

Under the favorable conditions of 2021, the timing of nitrogen application had surprisingly little effect on final outcomes. Split applications did not change aboveground biomass or grain yield, although delaying 50 percent of the nitrogen until the R1 stage temporarily reduced leaf area index and chlorophyll content. Crucially, the plants recovered. Once the second fertilizer dose was applied, all split treatments showed rapid nitrogen uptake during early reproductive growth, and by the R5 stage there were no significant differences in plant nitrogen uptake among the split treatments. This recovery demonstrates that maize can compensate for early-season nitrogen deficits when water is available, absorbing substantial nitrogen during grain filling when demand peaks.

The drought year told a different and arguably more important story. Under severe water stress, reducing the nitrogen rate to 50 percent of the full application—120 kilograms per hectare instead of 240—did not reduce biomass or grain yield compared to full rates. Even more striking, the reduced rate improved nitrogen uptake efficiency and agronomic efficiency while slashing residual soil nitrate. The 50 percent treatment left 83 percent less residual nitrogen in the soil than the full-rate treatments, and the 25 percent treatment left 58 percent less. In 2022, between 40 and 60 percent of applied nitrogen remained as residual soil nitrate after harvest in the full-rate plots, with the highest treatment accumulating nearly 160 kilograms of residual nitrogen per hectare—fertilizer that had been paid for but never used, sitting in the soil as a future source of water contamination.

The physiological measurements revealed why drought changed the calculus. When soil moisture is scarce, plants cannot take up nitrogen regardless of how much is available, so extra fertilizer simply accumulates. Chlorophyll readings, taken with a handheld SPAD meter, declined from the V6 stage onward in all plots in 2022, even as plant nitrogen uptake continued to rise slowly. In 2021, by contrast, plant nitrogen uptake explained 86 percent of the variability in chlorophyll content at the silking stage, but in 2022 that relationship broke down entirely when both growth stages were combined. The study also found that cutting nitrogen to 25 percent of the full rate significantly reduced plant height, leaf area, chlorophyll content, and grain yield—establishing that there is a floor below which nitrogen reduction becomes genuinely yield-limiting, even under stress.

The efficiency metrics told a nuanced story. In the drought year, nitrogen uptake efficiency and agronomic efficiency were highest in the reduced-rate treatments, meaning each kilogram of fertilizer produced more grain and was recovered more completely by the crop. However, nitrogen utilization efficiency—grain yield per unit of nitrogen in the plant—declined at the 25 percent rate, showing that the crop could not convert such scarce nitrogen into grain effectively. Delaying 50 percent of nitrogen until R1 produced the highest nitrogen utilization efficiency in 2022, hinting that well-timed late applications help the crop convert absorbed nitrogen into yield even under stress.

The practical implications are significant for dryland maize systems facing increasingly erratic weather. The findings suggest a strategy of applying 50 percent of nitrogen at planting and holding the remainder in reserve, then deciding based on seasonal conditions whether to apply it. In a wet year, the second application supports rapid uptake during the nitrogen-hungry reproductive stages. In a drought year, farmers can skip or reduce the second application, saving money on fertilizer and fuel while avoiding the accumulation of unused nitrate that could leach into groundwater or run off into the Gulf of Mexico. With nitrogen fertilizer prices having risen sharply in recent years, the economic argument aligns neatly with the environmental one.

The authors caution that the differences in seasonal precipitation limited their ability to test nitrogen strategies under ideal conditions in both years, and they recommend further validation in non-drought seasons. Still, the core message is clear and actionable: adaptive nitrogen management—splitting applications, monitoring the weather, and adjusting rates in real time—can maintain productivity, enhance nitrogen use efficiency, and reduce environmental risk in dryland maize production. In an era when agriculture must feed a growing population while shrinking its footprint on water and climate, getting the timing and amount of nitrogen right may be one of the most powerful levers available.

Subject of Research: Effects of split and reduced nitrogen fertilizer application on maize growth, yield, and nitrogen use efficiency under variable rainfall conditions

Article Title: Split nitrogen application to soil improves maize agronomic performance and nitrogen use efficiency

Article References: Bhattarai, K., Salehin, S. M. U., Rajan, N., & Schnell, R. W. (2026). Split nitrogen application to soil improves maize agronomic performance and nitrogen use efficiency. Discover Soil, 3(1), Article 144. https://doi.org/10.1007/s44378-026-00295-w

Image Credits: AI Generated

DOI: 10.1007/s44378-026-00295-w

Keywords: maize, nitrogen fertilizer, split application, nitrogen use efficiency, drought, dryland agriculture, residual soil nitrate, grain yield, chlorophyll content, leaf area index, agronomic efficiency, sustainable farming