The team’s central idea was to change the chemistry of the fertilizer microsite, the tiny zone of soil immediately surrounding each pellet where urea hydrolyzes within hours, pushing local pH above 8.5 and triggering ammonia losses. By coating or blending urea with biochars carrying a wide range of surface charges, the researchers aimed to slow nitrogen release and improve retention right where it matters. Biochar, a carbon-rich material produced by heating biomass in low-oxygen conditions, has long been studied as a soil amendment, but its properties vary enormously with feedstock, pyrolysis conditions, and post-production treatment. Rather than treating biochar as a single material, the team engineered four distinct versions and tested them head to head.

The biochars were produced from sawdust in a semi-airtight brick kiln, with temperatures climbing from 300 degrees Celsius at two hours to a peak of 807 degrees at 28 hours before declining. One batch was left pristine, with a nearly neutral surface charge of about minus 2.6 centimoles of charge per kilogram at pH 7.0. A second was chemically oxidized with hydrogen peroxide, which flooded the surface with carboxylic and phenolic functional groups and pushed the negative charge to minus 34.3 centimoles per kilogram. A third was biologically activated by inoculating it with microorganisms extracted from forest, agricultural, and pasture soils and incubating it for 15 days at alternating temperatures of 40 and 25 degrees. The fourth was pre-doped with iron, aluminum, and magnesium chlorides before pyrolysis, which impregnated the carbon matrix with metals and flipped the surface charge to slightly positive, around 1 centimole per kilogram, with a correspondingly tiny cation exchange capacity of about 2.4.

These four biochars were applied in two different architectures. In the coated formulations, urea granules were tumbled at 30 revolutions per minute with biochar, starch, and soybean oil at a urea-to-biochar ratio of 10:1, creating an external diffusion barrier around each pellet. In the blended formulations, biochar, fertilizer, and clay were physically mixed and pressed into new composite granules, so that nitrogen release depended on internal pore connectivity rather than an outer shell. Potassium nitrate was also blended with pristine and metal-doped biochars, and urea was blended with coal as an additional comparison. Because blending dilutes the nutrient content—the coated fertilizers contained roughly 40 percent nitrogen while the blends held only about 2.5 percent—application rates were adjusted so that every treatment delivered the same nutrient supply.

The field trial took place at the Agronomy Field of Patuakhali Science and Technology University in Dumki, Bangladesh, from January to May 2023, on a slightly alkaline silty clay loam with very low organic carbon of 0.98 percent and total nitrogen of just 0.05 percent. Twelve treatments were arranged in a randomized complete block design with three replications, spanning the biochar formulations, neem-coated urea, guti-urea (urea super granules), conventional prilled urea, and an unfertilized control. The hybrid maize variety Bahubali-881 was sown at 25 centimeters within rows spaced 60 centimeters apart, and nitrogen was split three ways: at land preparation, 40 days after sowing, and 75 days after sowing, just before flowering.

The standout result came from urea coated with biologically activated biochar. This treatment produced the highest grain yield of the entire experiment, 9.84 tonnes per hectare, a 174 percent increase over the unfertilized control’s 3.58 tonnes and a 29 percent increase over conventional urea’s 7.63 tonnes. The same plots produced the tallest plants at 202.73 centimeters, the longest cobs at 19.12 centimeters, the most grains per cob at roughly 590, the heaviest 1000-grain weight at 332.7 grams, and the highest SPAD chlorophyll reading at 54.7. Root biomass reached 3.81 tonnes per hectare, and straw yield peaked at 7.78 tonnes per hectare. Most strikingly, nitrogen use efficiency hit 74.4 percent, compared with just 47.6 percent for conventional urea—meaning nearly three-quarters of the applied nitrogen ended up in the crop rather than the environment.

The efficiency metrics told a consistent story across the board. The researchers calculated not only overall nitrogen use efficiency but also agronomic efficiency, the yield gain per unit of nitrogen applied; physiological efficiency, how well plant nitrogen converts into grain; and apparent recovery efficiency, the fraction of applied nitrogen recovered in plant tissue. The biologically activated biochar-coated urea led every index. Chemically oxidized biochar coatings and iron-aluminum-magnesium pre-doped coatings also matched or beat conventional urea and the commercial enhanced-efficiency products, neem-coated urea and guti-urea. When results were pooled by formulation type, coated fertilizers averaged 9.43 tonnes per hectare of grain and 65.32 percent nitrogen use efficiency, outperforming blended formulations, and oxidized biochar types averaged 9.78 tonnes per hectare and 69.3 percent efficiency.

Intriguingly, the soil itself offered few clues to the yield differences. Measurements of pH, ammonium nitrogen, and nitrate nitrogen during the growing season showed no statistically significant differences among treatments, and post-harvest analysis found most nutrients unchanged, with the notable exception of potassium, which was highest where potassium nitrate had been blended with biochar. Soil organic matter did vary, rising in several biochar-blended treatments. The authors attribute the modest soil effects to the small quantities of biochar applied, suggesting that the fertilizers’ benefits occurred locally around each pellet rather than across the bulk soil. Grain nutrient composition likewise remained stable, with no significant differences in micronutrients such as iron, zinc, and manganese, indicating that the yield gains came without sacrificing nutritional quality.

Multivariate statistics sharpened this interpretation. Pearson correlation analysis showed grain yield strongly and positively linked to plant traits—straw yield, grains per cob, root biomass, cob length, plant height, and 1000-grain weight—with correlation coefficients between 0.78 and 0.96, while residual soil nitrate after harvest correlated only weakly at 0.38. Redundancy analysis separated yield-related plant traits from soil nutrient variables along the first ordination axis, confirming that variation in harvest-time soil chemistry did not explain treatment performance. The authors are careful to note that mechanisms such as slower nitrogen release and improved synchronization between nitrogen supply and crop demand remain plausible explanations drawn from prior literature rather than processes directly measured in this study; urease activity and nitrogen transformation pathways were not evaluated.

Even with those caveats, the practical implications are substantial. Biologically activated biochar-coated urea is built from sawdust waste, soil microbes, starch, and soybean oil—no synthetic polymer coatings that linger in soil—making it an attractive candidate for smallholder maize farmers in Bangladesh and beyond, where yields still fall short of the regional irrigated potential of roughly 12.3 to 13.8 tonnes per hectare. The authors call for direct quantification of nitrogen release dynamics and loss pathways, along with validation across multiple seasons, locations, and economic conditions before large-scale adoption. If those follow-up studies hold up, a coating of microbe-conditioned charcoal could become one of the cheapest levers available for feeding more people while wasting less of the nitrogen that modern farming depends on.

Subject of Research: Biochar-coated and blended nitrogen fertilizers for improving maize yield and nitrogen use efficiency

Article Title: Role of biochar coated and blended nitrogen fertilizers on maize yield and nitrogen use efficiency

Article References: Alam, S. M., Mia, S., Saha, G., Masud, M. M., Al-Amin, M., Mim, M. J., Islam, M. M., & Jindo, K. (2026). Role of biochar coated and blended nitrogen fertilizers on maize yield and nitrogen use efficiency. Discover Plants, 3(1), Article 372. https://doi.org/10.1007/s44372-026-00835-2

Image Credits: AI Generated

DOI: 10.1007/s44372-026-00835-2

Keywords: biochar, urea, nitrogen use efficiency, maize, slow-release fertilizer, soil chemistry, Bangladesh, agronomy, sustainable agriculture, pyrolysis, enhanced-efficiency fertilizer, field trial

The research, published in the journal Plant and Soil, was led by Wenjia Yang, Xiaowei Ma, Jun Hou and Bing Cao of Yangtze University and the Beijing Academy of Agriculture and Forestry Sciences. The team set out to test a deceptively simple hypothesis. Controlled-release blended fertilizers, whose polymer coatings meter out nitrogen in step with crop demand, are known to raise yields and nitrogen use efficiency. But when these fertilizers are broadcast on the soil surface, as is common in practice, much of the nitrogen sits far from the densest concentration of rice roots, leaving it vulnerable to volatilization and runoff. Dense planting, the researchers reasoned, could close that gap by expanding the root absorption zone and intercepting nitrogen before it escapes.

To test the idea, the team ran a three-year field experiment with five treatments: a zero-nitrogen control, the conventional farmer’s practice, an optimized nitrogen practice, a single basal application of controlled-release blended fertilizer, and that same fertilizer combined with dense planting. Rather than tracking yield alone, they assembled an unusually complete environmental audit. They measured fluxes of methane and nitrous oxide from the paddies, ammonia volatilization from the floodwater, inorganic nitrogen in the soil and surface water, redox potential, dissolved oxygen, and the abundances of functional genes that govern the microbial nitrogen cycle. They then folded these measurements into greenhouse gas intensity, carbon footprint, and net ecosystem economic benefit calculations.

The yield results were striking. Compared with the farmer’s practice, the controlled-release fertilizer alone increased grain yield by 10 to 30 percent. Adding dense planting pushed yields a further 10 to 15 percent higher, and the mechanism behind the boost was a genuine synergy: the denser stands produced more effective panicles per unit area while each panicle also carried more grains. In other words, the combination did not simply cram more plants into the same space at the expense of individual performance; it lifted both components of the yield equation simultaneously, under a reduced nitrogen input regime.

The environmental accounting was equally revealing. The controlled-release fertilizer cut cumulative methane emissions by 18 to 35 percent, nitrous oxide emissions by 13 to 52 percent, and ammonia volatilization by 40 to 49 percent relative to conventional practice. These reductions trace back to the fertilizer’s core design. By releasing nitrogen gradually, the coating prevents the floodwater from becoming a concentrated nitrogen soup, which suppresses the microbial processes that generate nitrous oxide and the chemical equilibrium that drives ammonia into the air. The smoother nitrogen supply also alters the soil’s redox dynamics and dissolved oxygen profile, conditions that favor methanotrophs, the microbes that consume methane before it reaches the atmosphere.

Dense planting introduced one complication. Relative to the controlled-release fertilizer alone, the combined treatment showed a modest methane rebound of 13 to 14 percent, likely because denser canopies and root systems alter the carbon inputs and gas transport pathways in the flooded soil. The combination also did not further reduce nitrous oxide or ammonia losses beyond what the fertilizer achieved on its own. For a reader scanning only the emission columns, that might look like a step backward.

But the full accounting tells a different story. When emissions are expressed per unit of grain, the combined treatment held greenhouse gas intensity and carbon footprint at levels comparable to the fertilizer alone, because the yield gains diluted the per-kilogram emissions. The modest methane rebound was more than offset by the larger harvest. This yield-driven dilution is a critical insight for climate-smart agriculture: the goal is not simply to minimize absolute emissions from a field, but to minimize the emissions embedded in every bowl of rice produced.

The economics strengthened the case further. The combined treatment boosted net ecosystem economic benefits by 9 to 97 percent compared with the farmer’s practice, a range that reflects both higher grain output and savings on fertilizer and labor, since the controlled-release product requires only a single basal application rather than multiple split dressings. For smallholder farmers in central China, where rice paddies dominate the landscape and nitrogen overuse remains widespread, a practice that simultaneously raises income and cuts pollution addresses the two pressures that most often pull in opposite directions.

The study also connects to a broader scientific conversation about nitrogen-cycling microbes in paddy soils. By measuring the abundances of functional genes involved in nitrification and denitrification, the researchers could link treatment effects on nitrous oxide to shifts in the microbial communities that produce and consume this potent greenhouse gas, which has roughly 273 times the warming power of carbon dioxide over a century. Previous work by the same group and collaborators had shown that root-zone fertilization with controlled-release urea reduces nitrous oxide and ammonia losses under different irrigation regimes, and that combining controlled-release blended fertilizer with densification lowers ammonia volatilization. The new study extends that framework to a full greenhouse gas and carbon footprint assessment over multiple seasons, which is essential because single-year trials can be misleading in variable climates.

The authors conclude that controlled-release blended fertilizer combined with dense planting represents a promising strategy for sustainable rice production in the middle reaches of the Yangtze River, one of China’s most important rice belts. The findings arrive at a moment when rice systems worldwide face intensifying scrutiny: rice cultivation contributes a substantial share of agricultural methane, and global assessments consistently identify nitrogen management as a key lever for reducing the sector’s climate impact. If the yield-and-emissions synergy documented here holds across other rice regions, soil types, and cultivars, the humble act of planting rice a little closer together, with nitrogen delivered on the plant’s schedule rather than the farmer’s, could become one of the most cost-effective climate interventions in staple crop production. The next step, the researchers suggest, is verifying how the approach performs under the wider range of water management practices and soil conditions that define real-world rice farming across Asia.

Subject of Research: Effects of controlled-release fertilizer combined with dense planting on rice yield, greenhouse gas emissions, and carbon footprint

Article Title: Dense planting amplifies yield benefits of controlled-release urea while maintaining low environmental footprint in rice

Article References: Yang, W., Ma, X., Wang, X., Hou, J., Zou, G., & Cao, B. (2026). Dense planting amplifies yield benefits of controlled-release urea while maintaining low environmental footprint in rice. Plant and Soil. https://doi.org/10.1007/s11104-026-09125-y

Image Credits: AI Generated

DOI: 10.1007/s11104-026-09125-y

Keywords: rice, controlled-release fertilizer, dense planting, greenhouse gas emissions, methane, nitrous oxide, ammonia volatilization, carbon footprint, nitrogen use efficiency, paddy field, sustainable agriculture, Yangtze River

The research team, led by Asheesh Kumar and K. M. Manjaiah, synthesized two versions of the composite by grafting acrylic acid and acrylamide polymers onto bentonite nanoclay, replacing 20 percent of the acrylic acid with starch from either maize flour or mango kernel flour. The choice of biopolymer matters: fully synthetic polyacrylamide-based superabsorbents persist in soil and can generate toxic degradation by-products, whereas starch-grafted matrices biodegrade into benign compounds. Polymerization was carried out under a nitrogen atmosphere with ammonium persulfate as initiator and methylene bis-acrylamide as crosslinker, producing dry granules that were milled and sieved to a uniform two-millimeter size.

Characterization confirmed that the chemistry worked as designed. Fourier transform infrared spectroscopy showed that the characteristic silicate and starch peaks of the raw materials weakened or vanished after polymerization, while new bands near 1552 and 2321 wavenumbers signaled the formation of carbon-nitrogen and carbon-carbon linkages. X-ray diffraction revealed that bentonite’s diagnostic peak at a diffraction angle of 6.4 degrees disappeared entirely in the finished composites, indicating that the clay’s silicate layers had been exfoliated and dispersed throughout the polymer matrix, a hallmark of successful nanohybridization that improves barrier properties and mechanical strength. Scanning electron microscopy showed smooth, compact surfaces before loading and a rough, crystalline texture afterward, direct visual evidence that urea had been deposited across the polymer network.

The composites proved to be exceptional sponges. When one gram of dry material was immersed in water for 24 hours, the maize flour version absorbed roughly 68 grams of water and the mango kernel version about 62 grams, thanks to three-dimensional crosslinked networks of hydrophilic polymers studded with hydroxyl groups. This enormous swelling capacity is what allows the granules to soak up a urea solution, along with suspended microbial cultures, and then release both gradually in soil. The maize flour matrix absorbed more water than its mango kernel counterpart, likely because maize starch is richer in free hydroxyl groups, while mango kernel flour contains more fiber, protein, and phenolics that restrict swelling.

A critical question was whether the beneficial bacteria could survive inside a nitrogen-saturated polymer matrix. The researchers embedded Lactococcus lactis, a phosphorus solubilizer, and Pseudomonas aeruginosa, a zinc solubilizer, into the urea-loaded granules and tracked colony-forming units over 180 days. Both organisms remained viable throughout the six-month period. Lactococcus lactis held nearly steady, dropping only from 34 to 30 colony-forming units per plate, while Pseudomonas aeruginosa declined from 40 to 18. The team attributes this resilience to the composite’s porous structure and moisture retention: hydrogen bonding between water molecules and the polymer’s hydroxyl groups keeps the interior humid even when the exterior feels dry, and the nanoclay creates a protective microenvironment known to support bacterial survival.

The field trial, run during the 2021-22 kharif and rabi seasons on alluvial sandy loam at the IARI research farm, compared ten treatments in a randomized complete block design. The key comparison pitted 75 percent of the recommended nitrogen dose delivered through microbe-loaded composites against 100 percent of the recommended dose applied as prilled urea. Across maize and wheat, the composite treatments maintained higher and more sustained soil ammonium and nitrate levels, peaking around 60 days after sowing when crop demand is greatest. Notably, ammonium concentrations stayed significantly higher under the composite treatments than under full-dose urea, suggesting that the slow-release matrix delayed nitrification and kept nitrogen in a less leachable, less emission-prone form for longer.

The greenhouse gas results were striking. Using closed chambers and gas chromatography with electron capture detection, the team measured nitrous oxide fluxes weekly through the first 50 days of each crop. Full-dose urea produced average fluxes of 39.9 grams per hectare per day in wheat and 16.2 in maize, with peaks exceeding 120 and 35 grams per hectare per day respectively. The mango kernel composite with both bacterial cultures cut cumulative emissions by 17.2 percent in wheat and 21.4 percent in maize, while the maize flour composite performed even better, reducing emissions by 28.7 percent in wheat and 24.2 percent in maize. The mechanism is largely one of synchronization: by metering nitrogen out slowly and delivering 25 percent less of it, the composites shrink the pulses of excess mineral nitrogen that fuel nitrifying and denitrifying microbes, without starving the crop.

The solubilizing bacteria added a micronutrient bonus. Plots receiving composites with both cultures showed significantly higher phosphorus and zinc content in the grain and stover of both crops than plots receiving the composites alone. Phosphorus-solubilizing bacteria convert insoluble phosphates into plant-available forms through acidification and chelation, supporting ATP synthesis and root growth, while zinc solubilizers release zinc ions needed for enzymatic activity, protein synthesis, auxin regulation, and nitrogen metabolism. The result is a form of biofortification: more phosphorus and zinc sequestered in the edible grain, a meaningful consideration in regions where zinc deficiency affects human health.

Intriguingly, wheat emitted more nitrous oxide than maize despite growing in cooler winter conditions. The researchers link this asymmetry to irrigation. In the hot summer maize season, when temperatures reach 40 to 45 degrees Celsius, irrigation water vanishes within a day, allowing some applied nitrogen to leach away and leaving the soil too dry for maximal microbial activity. In winter, dew and cooler temperatures mean fields stay moist for five to seven days after irrigation, creating the anaerobic microsites in which denitrifying microbes thrive. The finding underscores that fertilizer technology interacts intimately with water management, and that emission mitigation strategies must account for both.

The authors are candid about limitations. The study covered a single site, one soil type, one climatic regime, and one maize-wheat rotation, and longer-term, multi-location validation is needed. The use of Pseudomonas aeruginosa, an opportunistic pathogen in clinical settings, also raises biosafety questions that will need addressing before widespread deployment. Still, the concept of a single granule that carries fertilizer, feeds beneficial microbes a moist refuge, and releases nutrients on the crop’s schedule rather than the soil’s is a compelling vision of climate-smart agriculture. If scaled economically, such composites could help cereal farmers grow more food with less nitrogen, fewer micronutrient deficiencies, and a substantially smaller greenhouse gas footprint.

Subject of Research: Slow-release urea nanoclay biopolymer composites with beneficial microbes for nutrient uptake and greenhouse gas mitigation in cereal cropping

Article Title: Urea-loaded nanoclay biopolymer composites integrated with beneficial microbes enhance nutrient uptake and mitigate greenhouse gas emissions

Article References: Kumar, A., Manjaiah, K. M., Roy, D., Saini, R., Bhatia, A., & Chauhan, A. P. S. (2026). Urea-loaded nanoclay biopolymer composites integrated with beneficial microbes enhance nutrient uptake and mitigate greenhouse gas emissions. Discover Soil, 3(1), Article 175. https://doi.org/10.1007/s44378-026-00334-6

Image Credits: AI Generated

DOI: 10.1007/s44378-026-00334-6

Keywords: nitrogen use efficiency, nanoclay biopolymer composite, urea, nitrous oxide, greenhouse gas emissions, plant growth-promoting rhizobacteria, phosphorus solubilizing bacteria, zinc solubilizing bacteria, slow-release fertilizer, maize-wheat cropping system, biofortification, climate-smart agriculture

The study, published in the Journal of Agriculture and Food Research, was carried out in Pingluo County, Ningxia, a warm temperate arid zone receiving a mere 177 millimeters of rain per year. Roughly 30 percent of the cultivated land in this region is moderately saline-alkali, part of the roughly 99 million hectares of such soil across China, of which more than 40 percent lies in the arid and semi-arid northwest. With per capita arable land in China below 40 percent of the global average, and maize covering about 43 million hectares and supplying more than 40 percent of total grain production, the stakes of squeezing more grain from degraded soils could hardly be higher. The research team, led by Yueqi Li and Jili Liu, set out to test whether matching nitrogen release to crop demand could rewire the entire physiology of the plant, not merely feed it more efficiently.

The experimental design was elegantly straightforward. Six treatments were compared in a randomized block layout with three replicates each: a no-nitrogen control, a conventional urea-only treatment, and four treatments in which 25, 50, 75, or 100 percent of the nitrogen was supplied as polyurethane-coated urea with a 60-day release period. Every treatment received identical total nutrients, 300 kilograms of nitrogen, 180 kilograms of phosphorus pentoxide, and 90 kilograms of potassium oxide per hectare, so any difference in performance could be attributed purely to the timing and pattern of nitrogen delivery. The maize cultivar Xianyu 1225 was sown at a high density of 90,000 plants per hectare, and all plots received the same 2,700 cubic meters of irrigation water, applied in equal installments at the six-leaf, twelve-leaf, and grain-filling stages.

The 50 percent substitution treatment, labeled T50, emerged as the clear winner across nearly every metric the team measured. Compared with conventional urea alone, it raised the leaf chlorophyll index by 11.65 percent and the net photosynthetic rate by 18.43 percent, while lowering intercellular carbon dioxide concentration, a sign that carbon was being fixed more vigorously. More dramatically, the activities of four key nitrogen-metabolism enzymes surged: nitrate reductase by 64.95 percent, glutamate dehydrogenase by 36.63 percent, glutamine synthetase by 22.07 percent, and glutamate synthetase by 60.41 percent. These enzymes form the biochemical pipeline that converts soil nitrate into amino acids, and their heightened activity indicates that the slow-release nitrogen was not merely present in the soil but actively being assimilated into plant metabolism throughout the season.

The concept that unifies the paper’s findings is the source-flow-sink framework, a classical model of crop yield formation. The source comprises the leaves that capture sunlight and build sugars; the flow is the vascular transport system that moves stored assimilates from stems and leaves into the developing ears; and the sink is the grain itself, whose capacity and activity determine how much of that assimilate can actually be packed into harvestable kernels. Salt stress sabotages all three links simultaneously. High pH and osmotic pressure impair root uptake of water and nutrients, reactive oxygen species accelerate chloroplast breakdown and leaf senescence, and poor assimilate supply starves the grain-filling process, shrinking both grain number and grain weight. The controlled-release fertilizer, the researchers found, repaired each link in sequence.

On the flow side, the results were particularly emphatic. Dry matter translocation, the movement of carbohydrates stored in stems and leaves into the grain after flowering, rose by 76.06 percent under T50 compared with urea alone, and the contribution of these pre-anthesis reserves to final grain yield climbed by nearly 18 percent. Grain filling, modeled with a logistic growth curve that fit the data with coefficients of determination above 0.98, was faster and heavier: the maximum filling rate increased by 32.48 percent, the average filling rate by 49.01 percent, and the peak filling date arrived nine days earlier. Ear weight, kernels per ear, and hundred-grain weight all rose by roughly 10 to 19 percent, confirming that the sink had genuinely expanded rather than simply being fed longer.

Why did 50 percent substitution outperform both lower and higher ratios? The authors argue that the answer lies in matching the nitrogen supply curve to the crop’s demand curve. Conventional urea floods the soil with available nitrogen early, promoting lush vegetative growth that later collapses into premature senescence when the supply runs out just as the grain-filling demand peaks. Pure controlled-release fertilizer, by contrast, releases nitrogen too slowly at the start, failing to support the rapid canopy expansion between the six-leaf and twelve-leaf stages and limiting the photosynthetic machinery that must be built early. The 50 percent blend, with conventional urea topdressed at two early stages and coated urea releasing steadily through mid-season, delivers what the authors describe as an early-stage support, mid-stage stability, late-stage sustainability pattern, sustaining leaf function precisely when salt stress would otherwise cut photosynthesis short.

The team backed these physiological interpretations with a battery of statistical tools. Mantel tests confirmed significant correlations between the substitution ratio and source traits such as leaf area index, leaf area duration, and chlorophyll content. Random forest modeling ranked dry matter translocation rate, stomatal conductance, and glutamate synthetase activity as the top contributors to grain yield, while grain weight per ear and mean filling rate dominated predictions of nitrogen use efficiency and irrigation water productivity. A partial least squares structural equation model then tied the whole story together: the substitution ratio acted positively on source, flow, and sink characteristics, with the strongest path coefficient, 0.71, linking it to sink traits, and sink characteristics in turn showed the strongest association with grain yield at 0.76. The model also revealed a negative association between the substitution ratio and the source-sink ratio, indicating a better balance between leaf supply and grain demand.

The efficiency gains carry real economic and environmental weight. Agronomic efficiency of nitrogen, the yield gained per kilogram of fertilizer applied, jumped by 72.79 percent under the optimal treatment, while nitrogen recovery efficiency rose by 68.39 percent and apparent recovery by 40.40 percent. Because irrigation volumes were identical across treatments, the 18.06 percent gain in irrigation water productivity reflects purely the yield increase, meaning every cubic meter of scarce irrigation water in this arid basin produced more grain. The authors caution, however, that their conclusions rest on two years of data from a single site, one maize cultivar, and a warm temperate continental climate, and that nitrogen loss pathways such as ammonia volatilization and nitrate leaching were inferred indirectly from plant uptake rather than measured directly in the soil.

Even with those caveats, the implications are considerable for a country wrestling with food security on degraded land. Controlled-release fertilizers remain more expensive than commodity urea, but a 50 percent substitution strategy halves the added cost while capturing most of the agronomic benefit, and the yield and efficiency gains documented here suggest the premium could pay for itself in saline-alkali regions. As China pushes to bring its vast salt-affected reserves into productive agriculture, the study offers a physiologically grounded template: rather than simply applying more fertilizer, farmers may get far more from every kilogram by controlling when the nitrogen arrives. The humble polymer coating, it turns out, does not just slow a chemical reaction. It re-orchestrates the entire source-flow-sink economy of the maize plant, turning hostile soil into a stage for one of the more quietly impressive yield breakthroughs of recent agronomy.

Subject of Research: Controlled-release fertilizer substitution effects on maize source-sink physiology, yield, and water-nitrogen use efficiency in saline-alkali soil

Article Title: Controlled-release fertilizer substitution boosts maize yield and water-nitrogen use efficiency via optimizing source-sink characteristics in saline-alkali soil

Article References: Controlled-release fertilizer substitution boosts maize yield and water-nitrogen use efficiency via optimizing source-sink characteristics in saline-alkali soil. (n.d.). https://doi.org/10.1016/j.jafr.2026.103312

Image Credits: AI Generated

DOI: 10.1016/j.jafr.2026.103312

Keywords: maize, controlled-release fertilizer, saline-alkali soil, nitrogen use efficiency, source-sink relationship, grain filling, dry matter translocation, irrigation water productivity, Ningxia, urea, photosynthesis, soil salinity