The shortcut in question is loss-on-ignition, or LOI, a technique beloved by monitoring agencies because it is fast, cheap and requires nothing more exotic than a furnace and a balance. A dried sediment sample is heated to 450 degrees Celsius for four hours, and the mass it loses is taken as a proxy for its organic matter content. Because organic carbon typically makes up only a fraction of that organic matter, the LOI value must then be converted into a total organic carbon, or TOC, estimate using a regression equation. The trouble, as the new study demonstrates, is that this conversion is not universal. It shifts with sediment composition, mineralogy and analytical protocol, meaning that a formula calibrated in one setting can quietly mislead in another.

The stakes are far from academic. Continental shelves cover roughly nine percent of the global seafloor, yet the top metre of subtidal, non-vegetated marine sediments is estimated to contain more than 2.3 trillion tonnes of organic carbon and to accumulate between 126 and 350 million tonnes each year. Fine-grained shelf deposits, including the Western Irish Sea mud belt, are recognised as hotspots of carbon accumulation, where silts and clays settling from suspension in low-energy waters carry organic matter down into long-term storage. Ireland’s Exclusive Economic Zone spans roughly 450,000 square kilometres, about ten times its land area, but its seabed carbon inventory remains poorly constrained despite years of mapping and sampling effort.

To test whether a single conversion equation could really serve such a varied environment, the team assembled an unusually rich dataset spanning surveys conducted between 2010 and 2023, drawing on the national INFOMAR mapping programme, Marine Institute monitoring cruises and the QUEST research project. Grab samples, box cores, gravity cores and vibrocores collected from the RV Celtic Voyager, RV Keary and RV Celtic Explorer yielded sediments ranging from coastal shallows less than five metres deep to the central basin at around 115 metres. Grain size was measured by laser diffraction, iron concentrations by portable X-ray fluorescence, and TOC by combustion elemental analysis after careful acid removal of carbonate carbon. Crucially, a subset of samples was analysed by both LOI and direct TOC methods, allowing the researchers to calibrate one against the other.

The paired measurements correlated strongly across the whole dataset, with a coefficient of determination of 0.948, and the baseline Western Irish Sea model took the form TOC equals 0.41 times LOI minus 0.18. That might sound like a success story, and in aggregate it is. But the residuals told a subtler tale. The pooled equation slightly over-predicted carbon in sandy, low-carbon samples and under-predicted it in carbon-rich muds, hinting that a single line was being forced through what were really two different populations of sediment.

Statistical tests made the split explicit. Chow tests, which probe whether a relationship changes abruptly across a threshold, identified significant structural breaks in the LOI-to-TOC relationship at 0.99 percent iron, 19.8 percent mud content and 29.6 metres water depth. Analysis of covariance confirmed that the regression slopes genuinely differed between the groups. The high-mud slope of 0.42 was nearly double the low-mud slope of 0.24, meaning that a given loss-on-ignition value corresponds to almost twice as much organic carbon in fine, deeper sediments as it does in shallow, sand-dominated ones. Mean TOC-to-LOI ratios reinforced the pattern, reaching 0.34 in fine sediments against just 0.20 in coarse ones.

The physical explanation lies in how minerals shelter organic matter from decay. Fine-grained matrices rich in clay minerals and iron or manganese oxides can bind organic molecules and protect them from microbial attack, allowing more carbon to persist per unit of organic matter. Iron phases such as oxyhydroxides and sulfides co-accumulate with organic carbon in quiet, fine-grained or oxygen-poor settings, which is why the iron threshold emerged as the strongest independent statistical split. The researchers are careful, however, to frame iron and water depth as proxies for depositional environment rather than proven causal controls, since all three variables co-vary with the fundamental grain-size regime of the seafloor.

Splitting the dataset at the 19.8 percent mud threshold produced group-specific models that improved fit markedly for high-mud sediments, reaching a coefficient of determination of 0.97, while the low-mud model, at 0.72, retained greater uncertainty. That asymmetry matters. In coarse sediments, where organic content is low and absolute LOI values are small, estimates are acutely sensitive to minor inorganic mass losses, structural water released from clays, salt effects and seasonal inputs of organic material. Prediction uncertainty is greatest in exactly these low-carbon sands, particularly for samples near the classification threshold, and the authors caution that extrapolating the fitted intercepts to near-zero LOI values is unreliable.

The study is equally candid about its own limits. The paired LOI-TOC subset is smaller than the full metadata set, group sizes are uneven at 18 high-mud and 59 low-mud samples, and the thresholds were chosen through exploratory analysis without independent validation. LOI itself, even when carefully performed, cannot match the specificity of direct combustion analysis, since ignition at 450 degrees Celsius drives off not only organic matter but also clay structural water and other volatile components. The authors stress that their models convert LOI to estimated TOC only; they do not by themselves quantify carbon stocks, accumulation rates, burial rates or climate-mitigation potential, all of which require dry bulk density, sediment thickness, spatial data, chronological constraints and rigorous propagation of uncertainty.

What the study does offer is a practical blueprint. Rather than treating LOI as a poor substitute for elemental analysis, the researchers position it as a way to extend the spatial reach of existing datasets, unlocking carbon estimates from archived samples where LOI was measured but TOC was not, provided paired calibration, sediment-class metadata and uncertainty estimates accompany the conversion. Just as importantly, the work demonstrates how routine geotechnical measurements, grain-size data and monitoring samples from mapping programmes, regulators, ports, offshore energy developers and commercial surveys can be woven together into national carbon inventories, reducing duplicated sampling and strengthening the evidence base on which marine spatial planning, protected area design and blue carbon accounting increasingly depend.

Subject of Research: Region-specific loss-on-ignition to total organic carbon conversion models for estimating blue carbon in Western Irish Sea marine sediments

Article Title: Region-specific LOI–TOC conversion models for marine sediment blue carbon assessment in the Western Irish Sea

Article References: Grey, A., Mhaoldomhnaigh, C. N., Chatting, M., Walsh, P., Lee, A., Kelleher, B., & Coughlan, M. (2026). Region-specific LOI–TOC conversion models for marine sediment blue carbon assessment in the Western Irish Sea. Environmental Monitoring and Assessment, 198(10), Article 1078. https://doi.org/10.1007/s10661-026-15918-6

Image Credits: AI Generated

DOI: 10.1007/s10661-026-15918-6

Keywords: blue carbon, marine sediments, loss-on-ignition, total organic carbon, Western Irish Sea, continental shelf, sediment classification, mud content, iron geochemistry, carbon stock assessment, seabed mapping, organic matter preservation

The Cañadón Asfalto Basin formed as part of the tectonic upheaval that accompanied the break-up of Gondwana, beginning in the Early Jurassic and continuing into the Late Cretaceous. North-westerly oriented half-grabens created isolated depocentres, and the Cerro Cóndor depocentre, in the middle Chubut River valley, preserves one of the most complete lacustrine successions of the period. The Cañadón Asfalto Formation itself is constrained between the Late Toarcian and Late Bajocian stages, an age anchored by biostratigraphically useful palynomorphs and a high-precision uranium-lead zircon date. At the Cañadón Lahuincó section, the team measured and sampled the succession bed by bed, collecting 51 outcrop samples of very fine-grained sandstones and siltstones for palynological processing using non-oxidative hydrochloric and hydrofluoric acids, a protocol chosen specifically to protect the natural colour and fluorescence of hydrogen-rich organic particles.

Palynofacies analysis, the technique at the heart of the study, examines the entire acid-resistant organic fraction of a rock rather than only the diagnostic spores and pollen grains. Each sample was quantified by counting a minimum of 500 particles under transmitted light microscopy, classifying them into structured organic matter such as palynomorphs, translucent and opaque phytoclasts, and unstructured amorphous organic matter. The researchers also assessed particle size, shape, colour, and fluorescence, and applied the thermal alteration index to gauge maturity. Cluster analysis using the Euclidean distance and unweighted pair group method grouped the samples into four distinct palynofacies types, designated PT-A through PT-D, plus one outlier sample whose organic matter had been baked by a thick andesite sill that intrudes the section. Total organic carbon measurements on 25 selected samples ranged from a mere 0.13 per cent to an impressive 11.96 per cent.

The sedimentological analysis revealed two complete depositional sequences, each telling a different chapter of the lake’s evolution. Sequence I, extending to about 197 metres above the base of the section, records a full transgressive-regressive cycle. Its lower part consists of fining- and thinning-upward cycles up to 10 metres thick, deposited when the lake was underfilled, meaning that water and sediment inflow could not keep pace with the accommodation space created by subsidence. In this state, lake levels fluctuated dramatically below the basin’s spill point, and marginal areas were periodically exposed, producing arid palaeosols and restricted water conditions that favoured phytoplanktonic productivity. The upper part of Sequence I flips the story: stacked coarsening-upward successions of littoral delta deposits indicate that the lake had transitioned to balanced-fill and ultimately overfilled conditions, in which the water level stabilised at the spill point and coastal progradation became possible.

Sequence II begins with an abrupt increase in accommodation, likely driven by renewed tectonic subsidence, and initially returns to underfilled conditions marked by shales interbedded with sandstones and thin limestones. The limestones, the authors interpret as punctuated episodes of lake restriction and alkaline waters during high-frequency regressive pulses. Then, at roughly 222 metres above the base, a sharp boundary marks what the researchers identify as a forced-regression surface, produced when the lake breached its spill point and entered fully overfilled conditions. Above this surface, thick coarsening-upward sandy cycles up to 30 metres record persistent progradation of littoral deltas into a freshwater lake, an overall progradational parasequence set that continues to the top of the measured section.

The palynological evidence maps beautifully onto this stratigraphic framework. Throughout the succession, land-derived material dominates, with phytoclasts making up between 31 and 100 per cent of the total organic assemblage, testifying to a strong terrestrial input into the basin. Yet the subtle shifts between this allochthonous plant debris and autochthonous algal material encode the climatic rhythm. Palynofacies types PT-A and PT-D signal wetter periods, when intensified rainfall drove extraordinary fluvial discharges, possibly including hyperpycnal flows, that swept high volumes of reworked terrestrial phytoclasts into the lake. PT-B, by contrast, marks drier intervals, and PT-C captures the transition between these opposing states. The ratio of equidimensional to blade-shaped opaque particles, a proxy for flow velocity, further supports this interpretation, with low values indicating distal accumulation from waning flows.

One of the most striking findings concerns the green colonial alga Botryococcus, whose well-preserved colonies with strong yellow fluorescence bloom in the assemblages during drier periods. Botryococcus is a tenacious coloniser of shallow, alkaline, oligotrophic to mesotrophic waters, equipped with desiccation-resistant walls and the ability to store large reserves of food, adaptations that allow it to survive conditions lethal to other algae. When evaporation outpaced runoff and the water body contracted, these algal blooms flourished, and their decay depleted oxygen in bottom waters, creating the dysoxic to anoxic conditions that allowed organic matter to be preserved with exceptional fidelity. The researchers note parallels with modern studies from southern Brazil, where algal dominance in lagoon sediments has been directly linked to twentieth-century drought episodes and falling water levels.

The taphonomic contrast between lake stages proved equally revealing. During the underfilled stage, terrestrial palynomorphs are scarce and poorly preserved, a pattern the authors attribute less to the absence of vegetation nearby than to the hostile chemistry of the lake water, whose pH conditions likely destroyed sporopollenin, the resilient biopolymer forming spore and pollen walls. The robust walls of Botryococcus and plant cuticles survived where sporomorphs did not. In the balanced-fill stage, by contrast, sporomorph-rich assemblages with well-preserved grains appear, dominated by Classopollis pollen from the Hirmerellaceae, which reaches up to 85 per cent of the sporomorph group, alongside araucariacean and podocarpacean pollen whose distribution patterns help distinguish proximal delta-plain settings from more distal depositional environments.

The study also carries practical weight for petroleum geoscience. Kerogen in the analysed samples ranges from gas-prone Type III, dominated by terrestrial material, to mixed Type I/III in the algae-rich intervals, and thermal alteration indices between 2+ and 3− indicate an early to middle-mature, oil- and gas-prone stage. Given the predominance of Type III kerogen, the authors conclude that the Cañadón Asfalto Formation deposits at this locality represent a potential unconventional shale gas reservoir. More broadly, the work underscores that lacustrine basins cannot be treated as miniature oceans: their water levels, chemistry, and organic archives respond to climate with a sensitivity that marine systems rarely match. By reading the microscopic organic particles locked in Patagonian mudstones, geologists can now reconstruct, cycle by cycle, how a Jurassic lake breathed with the rhythm of ancient monsoons, and how those same rhythms determined which carbon was destined to become tomorrow’s energy resource.

Subject of Research: Palynofacies analysis and lacustrine sequence stratigraphy of the Jurassic Cañadón Asfalto Formation in Patagonia, Argentina

Article Title: Palynofacies and lacustrine sequence stratigraphy: a case example from the Jurassic Cañadón Asfalto Formation, Cañadón Asfalto Basin, Extra-Andean Patagonia, Argentina

Article References: Olivera, D. E., Zavala, C., Quattrocchio, M. E., Soreda, M. E., Scasso, R., & Yang, R. (2026). Palynofacies and lacustrine sequence stratigraphy: a case example from the Jurassic Cañadón Asfalto Formation, Cañadón Asfalto Basin, Extra-Andean Patagonia, Argentina. Journal of Micropalaeontology, 45(1), 335-357. https://doi.org/10.5194/jm-45-335-2026

Image Credits: AI Generated

DOI: 10.5194/jm-45-335-2026

Keywords: palynofacies, lacustrine sequence stratigraphy, Cañadón Asfalto Formation, Jurassic, Patagonia, Botryococcus, organic matter preservation, kerogen, total organic carbon, paleoclimate, underfilled lake, source rock

The scale of the problem the review addresses is stark. Intensive monoculture farming has degraded about 33 percent of global soils, stripping away organic matter, eroding fertility, and disrupting the microbial communities that cycle nutrients. Agriculture already consumes around 70 percent of the world’s freshwater, and water scarcity now touches roughly 40 percent of the global population, a figure that climate change is pushing higher through altered rainfall patterns and increased evapotranspiration. Continuous monocropping compounds these pressures by depleting soil organic carbon and leaving fields vulnerable to erosion, while shallow-rooted cereal monocultures exploit only the upper layers of the soil profile, wasting nutrients and water locked deeper below.

Crop diversification attacks these weaknesses through several complementary mechanisms. Intercropping, the practice of growing two or more crop species together on the same land, exploits complementary root architectures and nutrient demands so that the mixture captures resources a single crop cannot. The review’s synthesis of global studies found that intercropping systems consistently reduce pest incidence by 10 to 50 percent compared with monocultures, and that their Land Equivalent Ratios, a measure of yield advantage, reliably exceed 1.0, meaning the same land produces more food when planted with mixtures than when split between separate monocultures. Maize-legume combinations, for example, cut pest pressure by 20 to 50 percent while legumes fix atmospheric nitrogen and enrich the soil for their neighbors.

The soil benefits are measurable and substantial. Crop rotation and cover cropping were found to raise soil organic carbon by 8 to 22 percent and reduce soil bulk density, an indicator of compaction, by 5 to 15 percent across alluvial and black soil environments in India. Conservation agriculture, which combines minimal tillage with permanent soil cover and diverse rotations, improved water retention and cut runoff by up to 40 percent relative to conventional tillage. Cover crops such as cereal rye and hairy vetch suppressed weeds by as much as 95 percent while their deep roots opened channels for water infiltration. In one striking example, maize-soybean intercropping increased fodder production by 28 percent and boosted available phosphorus in the rhizosphere by 26 to 74 percent, alongside a 26 to 46 percent rise in acid phosphatase enzyme activity, a signature of heightened microbial nutrient cycling.

Agroforestry, the integration of trees and shrubs into cropland, emerged as the review’s standout tool for climate mitigation. Tree-based systems sequester soil organic carbon at rates of 0.3 to 1.2 megagrams of carbon per hectare per year, while their canopies buffer crops against heat and wind, their roots stabilize soil against erosion, and their presence creates habitat for beneficial insects that pollinate crops and prey on pests. Farmers gain additional income streams from timber, fruit, and nuts, which cushions them against the market volatility that plagues single-crop operations. The review notes, however, that agroforestry demands longer time horizons and higher upfront investment than other diversification strategies, which limits its uptake among resource-poor smallholders.

The evidence base spans remarkably diverse environments. In India’s wheat belts on sandy-loam alluvial soils, adding chickpea or monsoon-season legumes such as pigeonpea and greengram reduced bulk density and increased organic carbon fractions, infiltration, and available nitrogen, phosphorus, and potassium. Rice-wheat systems diversified with maize, black-gram, cabbage, and sesame delivered higher system productivity and profitability together with greater bacterial abundance and enzyme activity. On heavy black Vertisols, cereal-pulse integrations enhanced total productivity while reducing runoff and soil loss. Cotton systems benefited from legume and millet intercrops under rainfed conditions, and sugarcane fields with strategic intercrops showed enhanced microbial biomass carbon, respiration, and land-equivalent ratios. From West Bengal to Tamil Nadu, the pattern held: diversification regenerated soils while lifting yields and profits.

What makes the review particularly timely is its argument that modern technology can accelerate an ancient practice. Precision agriculture tools, including remote sensing, geographic information systems, drones, and Internet of Things sensors, now allow farmers to optimize which crop combinations suit specific fields and to monitor soil moisture, nutrient status, and crop health in real time. In Brazil, precision techniques manage multi-crop plantings of soybeans, maize, and coffee; in India’s Punjab, soil sensors and satellite imagery complement traditional rotation practices. Digital platforms are also dissolving market barriers: India’s e-NAM electronic trading platform and Kenya’s DigiFarm mobile service, which has enrolled more than 1.3 million smallholder farmers, connect growers of diverse crops with buyers, inputs, and credit, making diversification economically viable rather than merely agronomically sound.

The review is equally emphatic that technology alone will not suffice; social infrastructure matters just as much. Farmer Field Schools in Indonesia and Kenya let growers experiment with intercropping and agroforestry under expert guidance. Community seed banks in Nepal preserve locally adapted varieties and keep genetic diversity in circulation. In Malawi, a farmer-to-farmer extension model called MAFFA, in which trained farmers themselves became the knowledge messengers, produced nearly 1.8 times higher groundnut yields per unit area with significantly lower aflatoxin contamination than conventional approaches. In Latin America, the Campesino a Campesino movement demonstrated that peer-to-peer learning transfers agroecological techniques more cheaply and acceptably than top-down extension services. Participatory plant breeding in Ethiopia produced barley varieties that farmers actually adopted because they helped select them.

Policy emerges as the final, decisive lever. India’s minimum support prices for pulses and millets are nudging farmers away from cereal monocultures, while the European Union’s Common Agricultural Policy pays farmers directly for diversification as part of its greening requirements. Subsidies, tailored credit and insurance schemes, and investment in breeding climate-resilient varieties all lower the barriers to transition. The review’s authors are candid about remaining gaps: long-term field trials exceeding ten years are scarce, particularly in South Asia, and the short-term yield penalties that can occur while a degraded monoculture converts to a diversified system deserve careful quantification. But their overall conclusion is unambiguous. No single practice outperforms all others everywhere; instead, complementary combinations, such as intercropping embedded within rotations or agroforestry paired with cover crops, deliver the greatest cumulative gains in soil carbon, biodiversity, and yield stability. As climate volatility intensifies and arable land shrinks, the review suggests that the future of food security may depend less on inventing something new than on reassembling something old, intelligently, at scale, and with the full toolkit of the twenty-first century behind it.

Subject of Research: Crop diversification practices such as intercropping, agroforestry, and crop rotation for improving agroecosystem resilience, soil health, and food security

Article Title: Crop diversification as an effective approach for improving agroecosystem resilience and food security

Article References: Meena, S., Tater, A., Kumar, S., Meena, A. R., Sharma, N. K., Roy, A., & Thapa, A. (2026). Crop diversification as an effective approach for improving agroecosystem resilience and food security. Discover Soil, 3(1), Article 103. https://doi.org/10.1007/s44378-026-00257-2

Image Credits: AI Generated

DOI: 10.1007/s44378-026-00257-2

Keywords: crop diversification, intercropping, agroforestry, soil health, food security, crop rotation, cover crops, conservation agriculture, biodiversity, climate resilience, precision agriculture, smallholder farmers