Traditionally, researchers have evaluated nitrogen fixation in peanut using measurements taken at specific, isolated growth stages. This snapshot approach often fails to capture the full trajectory of the process, which is influenced by a myriad of interacting variables. The review emphasizes that biological nitrogen fixation should be viewed as an integrated, season-long trait rather than a series of discrete events. Key factors influencing this process include the specific peanut genotype, the effectiveness of the rhizobial partners, soil nitrogen availability, water status, temperature, and the developmental stage of the crop. Understanding these interactions is critical for developing cultivars that can reliably fix nitrogen under varying field conditions.

The physiological regulation of nitrogen fixation involves a delicate balance of carbon allocation, oxygen diffusion, and enzymatic activity. The plant must allocate sufficient carbon to the nodules to fuel the energy-intensive process of nitrogenase activity, which converts atmospheric nitrogen into ammonia. Simultaneously, the nodules must maintain optimal oxygen levels to support respiration without inhibiting the oxygen-sensitive nitrogenase enzyme. The review details how feedback inhibition occurs when soil nitrogen levels are high, leading to a reduction in nodule formation and nitrogenase activity. This regulatory mechanism ensures that the plant does not expend unnecessary energy on nitrogen fixation when soil nitrogen is readily available, but it also complicates breeding efforts aimed at maximizing fixation across diverse environments.

Characterizing nitrogen fixation across time and environments requires advanced methodological tools. The review evaluates the complementary contributions of stable-isotope methods, nodulation traits, physiological indicators, and high-throughput phenotyping. Stable-isotope techniques, such as the use of nitrogen-15, allow for precise quantification of nitrogen derived from the atmosphere (Ndfa), providing a direct measure of fixation efficiency. Nodulation traits, including nodule number, size, and weight, offer indirect indicators of symbiotic potential. Physiological indicators, such as photochemical reflectance index (PRI) and poly-β-hydroxybutyrate (PHB) content, provide insights into the metabolic status of the nodules. High-throughput phenotyping enables the rapid assessment of large populations, facilitating the identification of genotypes with superior fixation capabilities under various stress conditions.

Genomic resources are increasingly becoming central to understanding the genetic basis of nitrogen fixation. The review highlights the utility of quantitative trait locus (QTL) mapping, multi-parent advanced generation inter-cross (MAGIC) populations, telomere-to-telomere (T2T) reference genomes, multi-omics approaches, and genomic selection. QTL mapping helps identify specific genomic regions associated with fixation-related traits, while MAGIC populations provide a powerful tool for dissecting complex genetic architectures by combining multiple parental lines. T2T reference genomes offer a complete view of the peanut genome, including previously uncharacterized regions that may harbor important genes. Multi-omics integration, combining genomics, transcriptomics, proteomics, and metabolomics, provides a holistic understanding of the molecular mechanisms underlying nitrogen fixation. Genomic selection allows for the prediction of fixation-related performance in breeding populations, accelerating the development of improved cultivars.

Despite these advances, significant challenges remain in translating genomic insights into practical breeding outcomes. The review notes that direct evidence linking peanut MAGIC populations and genomic prediction models specifically to season-long biological nitrogen fixation is still limited. The transfer of detected QTL into breeding programs is constrained by moderate heritability, genotype-by-environment (G × E) interaction, and methodological variation among studies. G × E interaction means that a genotype that performs well in one environment may not perform well in another, complicating the selection of broadly adapted cultivars. Moderate heritability indicates that a substantial portion of the variation in nitrogen fixation is due to environmental factors rather than genetic differences, further challenging breeding efforts. Methodological variation among studies, including differences in measurement techniques and experimental designs, makes it difficult to compare results and validate findings across different research groups.

To address these gaps, the authors propose a breeding framework in which season-long fixation is measured through standardized longitudinal phenotyping. This approach involves tracking nitrogen fixation over the entire growing season, rather than relying on single-time-point measurements. By evaluating fixation jointly with yield, quality, stress tolerance, and nitrogen-use efficiency, breeders can develop cultivars that are not only high-fixing but also productive and resilient. Standardized longitudinal phenotyping requires coordinated efforts to establish common protocols and data-sharing platforms, enabling the integration of data from multiple environments and genotypes. This framework would allow for a more accurate assessment of the genetic potential for nitrogen fixation and its stability across different conditions.

Addressing the challenges in peanut nitrogen fixation research will require coordinated studies integrating peanut genotypes, rhizobial partners, soil conditions, multi-environment trials, and genomic data. The interaction between the plant and its rhizobial partner is a critical determinant of fixation efficiency, and understanding this interaction at the molecular level is essential for improving symbiosis. Soil conditions, including pH, texture, and nutrient status, also play a significant role in regulating nitrogen fixation, and these factors must be considered in breeding and management strategies. Multi-environment trials are necessary to evaluate the stability of fixation across different agro-ecological zones, while genomic data can help identify the genetic basis of this stability. By integrating these diverse data streams, researchers can develop a more comprehensive understanding of the factors controlling nitrogen fixation in peanut.

Such an approach could support the development of peanut cultivars that contribute more reliably to sustainable and climate-resilient cropping systems. As climate change continues to alter environmental conditions, the ability of crops to maintain productivity under stress is becoming increasingly important. Peanut cultivars with robust nitrogen fixation capabilities can reduce the need for synthetic fertilizers, lowering production costs and environmental impacts. Moreover, these cultivars can improve soil health by increasing organic matter and promoting microbial activity. The development of such cultivars will require a long-term commitment to research and breeding, involving collaboration between scientists, breeders, and farmers. By leveraging the latest advances in physiology, genetics, and phenotyping, the peanut research community can make significant strides toward more sustainable crop production.

Subject of Research: Physiological and genetic regulation of seasonal biological nitrogen fixation in peanut

Article Title: Physiological and genetic regulation of seasonal biological nitrogen fixation in peanut for sustainable crop production

Article References: Abbas, A. A., Wasim, A., Mengistu, A., & Gelaye, Y. (2026). Physiological and genetic regulation of seasonal biological nitrogen fixation in peanut for sustainable crop production. Discover Sustainability. https://doi.org/10.1007/s43621-026-05086-5

Image Credits: AI Generated

DOI: 10.1007/s43621-026-05086-5

Keywords: peanut, biological nitrogen fixation, sustainable agriculture, plant breeding, genomic selection, rhizobium, crop productivity, soil health, climate resilience, phenotyping, Physiological, genetic

The team selected Kanchanpur purposively because of its considerable potential for wheat cultivation, and carried out the research during March and April of 2022. Using a simple random sampling technique, they systematically chose one hundred wheat-farming households across the district. Primary data were collected through pre-tested semi-structured questionnaires administered in face-to-face interviews, while secondary data were drawn from relevant journals and official records. This dual approach allowed the researchers to capture both quantitative production figures and the lived experience of farmers struggling with unreliable inputs and market access.

To determine which variables actually drive wheat production, the researchers applied a multiple regression model to their survey data. The analysis revealed that four factors exerted a significant positive influence on output: the quantity of applied NPK fertilizer, meaning the combined nutrients nitrogen, phosphorus, and potassium; the educational level of the household head; the extent of wheat-cultivated land equipped with irrigation facilities; and the farmers’ years of experience in the field. Each of these variables, when increased, was associated with measurably higher wheat production in the study area.

The fertilizer finding is particularly consequential. Nitrogen, phosphorus, and potassium are the backbone of modern cereal nutrition, and inadequate or poorly timed application directly limits grain filling and tillering in wheat. In Kanchanpur, however, farmers frequently cannot obtain chemical fertilizer at all during the critical growth periods when the crop needs it most. The study identifies this unavailability of fertilizer during key developmental stages as the single most severe constraint on wheat production in the district, a problem that undermines even the most experienced farmers’ efforts.

Education emerged as another powerful lever. Households headed by individuals with more formal schooling tended to produce more wheat, a pattern consistent with the idea that educated farmers are better positioned to interpret agronomic recommendations, calculate appropriate input doses, adopt improved technologies, and navigate extension services. Similarly, the area of wheat land with reliable irrigation proved decisive. Wheat in the Terai plains is often grown after rice on residual soil moisture, and access to controlled water supply allows farmers to time irrigation at critical stages such as crown root initiation and grain filling, protecting yields against the erratic rainfall that increasingly characterizes the region.

Experience also mattered. Farmers with more years in the field achieved higher production, reflecting accumulated knowledge of local soil behavior, sowing windows, variety selection, and pest management. This finding suggests that extension programs could gain leverage by pairing experienced lead farmers with newer producers, transferring practical know-how that formal training alone often fails to convey. It also hints at a generational risk: as older, seasoned farmers retire from cultivation, their tacit agronomic knowledge may not be replaced quickly enough to sustain district-level output.

Beyond the regression results, the researchers used an indexing method to rank the major constraints farmers face. After fertilizer unavailability, the second most damaging problem was crop destruction by wild animals and stray cattle. In Kanchanpur, proximity to forest areas and wildlife corridors means that nilgai, wild boar, monkeys, and roaming domestic livestock frequently invade fields overnight, flattening standing crops and eating grain. Farmers respond with watch huts, night patrols, and noise deterrents, but these measures demand labor and rarely provide complete protection, effectively taxing every harvest.

The indexed ranking also highlighted the lack of access to improved seeds and irrigation as a major constraint. Improved, disease-resistant wheat varieties can raise yields substantially, but many farmers in the district continue to sow saved or uncertified seed because quality seed is not available locally or is priced beyond reach. Combined with limited irrigation infrastructure, this leaves crops vulnerable to moisture stress and to the diseases and pests that the study lists among the significant production challenges. Inadequate market access rounds out the constraint list, with farmers facing poor roads, weak price information, and limited buyer networks that reduce the incentive to invest in higher inputs.

The comparative context sharpens the urgency of these findings. Districts such as Kailali, Banke, Kapilbastu, and Rupandehi, operating under similar weather patterns, achieve higher wheat productivity than Kanchanpur, which indicates that the yield gap is not dictated by climate but by controllable factors: input supply chains, irrigation coverage, seed systems, and market institutions. The study’s authors argue that addressing these bottlenecks could unlock the district’s considerable prospective for wheat cultivation, contributing to national food security at a time when cereal imports and price volatility weigh heavily on Nepal’s economy.

For policymakers, the message is that raising wheat output in Kanchanpur requires coordinated intervention rather than isolated fixes. Ensuring timely fertilizer availability during critical growth periods, expanding irrigation infrastructure, improving the distribution of improved seed, managing human-wildlife conflict around farmland, and strengthening market linkages together form the pathway the evidence points toward. The regression results show that farmers respond strongly when given the means, more nutrients, more water, more knowledge, and more experience, while the constraint indexing shows exactly where the system currently fails them. Closing that gap between potential and performance could transform wheat farming in Kanchanpur from a marginal enterprise into a reliable contributor to Nepal’s grain supply.

Subject of Research: Factors affecting wheat productivity and production constraints in Kanchanpur district, Nepal

Article Title: An assessment of factors affecting productivity and production limitations of wheat farming in Kanchanpur district of Nepal

Article References: Kafle, K., & Joshi, P. P. (2024). An assessment of factors affecting productivity and production limitations of wheat farming in Kanchanpur district of Nepal. Innovations in Agriculture, 7, 1–8. https://doi.org/10.3897/ia.2024.124216

Image Credits: AI Generated

DOI: 10.3897/ia.2024.124216

Keywords: wheat farming, Nepal, Kanchanpur, crop productivity, NPK fertilizer, irrigation, improved seeds, multiple regression, wild animal damage, market access, agricultural constraints, food security

The review begins with a principle that has governed plant nutrition for decades. Essentiality means that the absence of even one essential plant nutrient element renders growth or reproduction impossible. By convention, the essentials for plant nutrition include carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, zinc, manganese, copper, boron, chlorine, molybdenum, nickel, and, to the extent that it is accepted as an essential mineral element, cobalt. On a dry-weight basis, the elements derived from air and water, namely carbon, hydrogen and oxygen, account for roughly 94 to 96 percent of plant biomass. The primary macronutrients make up about 2 to 3.5 percent, the secondary macronutrients about 0.5 to 1.5 percent, and the micronutrients less than 0.1 percent of dry mass. Despite their small share, the authors emphasize, these elements sustain light harvesting, water oxidation, electron transport, ATP and NADPH production, the carbon reactions, and the integration of photosynthesis with the metabolism of the whole plant.

To understand why, it helps to revisit the architecture of photosynthesis. Two pigment-protein systems embedded in the thylakoid membrane of the chloroplast, Photosystem I and Photosystem II, mediate light absorption, excitation energy transfer, primary photochemistry, electron transfer, the oxidation of water, and the reduction of NADP+ to NADPH. In addition to electron transfer, several membrane complexes release protons into the thylakoid lumen, generating a proton gradient that is exploited by ATP synthase to produce ATP. The NADPH and ATP are then used to convert carbon dioxide into carbohydrates via the C3 and C4 pathways, packing energy into sugar bonds. Each of these steps depends on specific elements. Magnesium sits at the center of every chlorophyll molecule, both in the antenna complexes that harvest sunlight and in the reaction-center chlorophylls of Photosystems I and II that drive electron transfer from water to NADP+. Manganese and calcium form the Mn4CaO5 cluster of Photosystem II, the site of water splitting and oxygen evolution. Iron and sulfur together build the iron-sulfur clusters of the cytochrome b6f complex, Photosystem I and ferredoxin, while copper is the redox cofactor of plastocyanin, the mobile carrier that transfers electrons from the cytochrome b6f complex to Photosystem I.

The air- and water-derived elements play roles that go beyond serving as the molecular framework of substrates and products. Carbon is the backbone of all organic molecules, and in plants it is primarily acquired from atmospheric carbon dioxide, which diffuses into leaves through stomata and serves as the inorganic carbon source for the Calvin-Benson-Bassham cycle. But the bicarbonate ion is also a critical cofactor of Photosystem II, regulating the photosynthetic electron transport chain. Hydrogen and oxygen make up the water that is split during water oxidation, the core of oxygenic photosynthesis because it generates molecular oxygen. Furthermore, the hydrogen ions released during water oxidation and other steps play essential roles in generating the pH gradient across the thylakoid membrane that leads to ATP production. The stoichiometry is demanding: the fixation of six carbon dioxide molecules via the Calvin-Benson-Bassham cycle, corresponding to the synthesis of one glucose equivalent, requires 18 ATP and 12 NADPH molecules, while the oxidation of two water molecules at Photosystem II supplies four electrons that drive the formation of two NADPH molecules and a proton-motive force sufficient to synthesize up to three ATP molecules.

Nitrogen occupies a special place among the macronutrients because its influence on photosynthesis does not saturate the way most mineral nutrients do. Leaf nitrogen content shows an approximately proportional relationship with photosynthetic capacity across a wide physiological range, a relationship that arises because a large fraction of nitrogen is invested directly in the photosynthetic apparatus within the leaf, particularly in rubisco and the thylakoid proteins of the electron transport chain. The capacity for electron transport in the chloroplast is directly proportional to cytochrome f content, and nitrogen assimilation is integral to carbon assimilation. Nitrogen is a constituent of amino acids, proteins, chlorophyll, nucleic acids, NADPH and ATP, and it is a building block of the enzymes of the Calvin-Benson-Bassham cycle. Nitrogen use and allocation differ substantially between C3 and C4 plants, a distinction with consequences for how crops respond to fertilization under different climates.

Phosphorus and potassium complete the primary macronutrient picture with distinct technical roles. Phosphorus is a constituent of inorganic phosphate and of the key energy-transfer molecules NADP, NADPH, ADP and ATP, and it is embedded in the thylakoid membrane as phospholipids. Under phosphorus deficiency, the photosynthetic electron transport chain is disrupted, ATP synthase activity is restricted, and carbon dioxide fixation is reduced, linking phosphorus to both the light reactions and the carbon reactions. Potassium, meanwhile, is involved in transmembrane transport and enzyme activation. Ion transporters and potassium channels are integrated into the thylakoid, where a potassium channel activates plastoquinone and a potassium/hydrogen antiporter stimulates electron transport. Energy conversion may be affected by modulation of acidification through thylakoid and lumen potassium and chloride channeling. Potassium also facilitates carbon dioxide diffusion into chloroplasts and is involved in the transport of photosynthates throughout the plant.

The secondary macronutrients and micronutrients reveal how tightly the light and carbon reactions are coupled through metal chemistry. Calcium is part of the Mn4CaO5 cluster required for water oxidation and oxygen evolution, and it is implicated, by still unknown mechanisms, in the regulation of electron transfer and carbon reaction proteins. Magnesium is required for key Calvin-Benson-Bassham cycle enzymes and for rubisco activation, and all reactions involving ATP require magnesium ions. Sulfur is associated with iron in the Rieske iron-sulfur protein of the cytochrome b6f complex and is part of several Photosystem I components and ferredoxin, and it is a component of methionine and cysteine, two amino acids central to photosynthetic protein complexes. Zinc is a cofactor of the copper/zinc superoxide dismutase and carbonic anhydrase, contributing to carbon metabolism. Boron is required for the regulation of carbohydrate metabolism in the carbon reactions. Molybdenum is present in four metalloenzymes that catalyze redox reactions in plants, particularly those involved in nitrogen assimilation, and it improves chloroplast configuration and increases chlorophyll content. Chlorine, in the form of chloride ions, is required for Photosystem II activity and is involved in the regulation of proton transfer during water oxidation, acting as an essential micronutrient for Photosystem II photoassembly and photosynthetic oxygen evolution. Nickel and cobalt play indirect roles, mainly as cofactors of the nickel/cobalt transporter-permease NiCo-PIC1, which transports ferrous iron through the inner membrane of the chloroplast, and cobalt is a chaperone of copper in the copper/zinc superoxide dismutase.

The authors also stress that elements work as teams within protein complexes, and that these team relationships are equally essential. Iron and sulfur partner in a Rieske protein. Calcium and manganese partner in the Mn4CaO5 cluster and again in lectins. Cobalt, zinc and copper cooperate in the copper/zinc superoxide dismutase. Iron, nickel and cobalt cooperate in NiCo-PIC1. Metal transporter families, including ABC, CAX, CCX, CDF/MTP, ECA, HMA, NRAMP, OPT, VIT and ZIP, enable the uptake and movement of these nutrients, and transporters coordinate the interplay of compounds, metals and metalloids that regulate the acquisition, distribution and efficient utilization of essential plant nutrients. Close to a third of all known enzymes are associated with the metal elements calcium, magnesium, iron, manganese, zinc, copper, nickel and cobalt, and these elements are required for the activity of their respective metalloenzymes. The activity of cobalt in chloroplast functions, the authors note, supports its classification as an essential element, and like nickel its optimal foliar dose may be in the nanomolar range.

Signaling and crosstalk emerge as the connective tissue that directs the metabolic pathways of photosynthates such as sugars. Recent work summarized in the review shows that signaling between nitrogen, phosphorus, sulfur, zinc and iron may involve complex crosstalk processes in response to nutrient deficiency, and that dynamic nutrient signaling networks connect sugar, nitrate and phosphate in controlling molecular pathways. Carbon and nitrogen assimilation are integrated processes, and co-application of elevated carbon dioxide with nitrogen promotes the synthesis of nitrogenous products key to growth, while molybdenum plays key roles in nitrogen assimilation. Several enzymes in the path of carbon are activated by the reduction of disulfide bonds on conversion, in light, of ferredoxin reduced in Photosystem I to a thiol signal, meaning that the light and carbon reactions employ sulfur to transmit signals in the process of photosynthesis. Deficiencies of secondary fertilizers such as calcium, magnesium and sulfur in lateritic and leached acid soils are growing concerns for farm production precisely because these minerals are vital to photosynthesis. Where a deficiency of any element is diagnosed, supplementation by foliar applications is recommended, and because the light reactions of photosynthesis are measured in picoseconds, nutrients cannot be drawn up from roots in the soil to the shoot with such rapidity, making foliar placement at the site of the photosynthetic processes potentially important.

The review closes with a forward-looking argument for agriculture and for the transfer of photosynthesis-related technologies to the field. When treating crops with plant growth regulators, nitrogen input plays integral roles in carbon partitioning, and co-application of essential plant nutrient elements with regulators such as methyl-alpha-D-mannopyranoside, a plant growth regulator for photosynthesis, were found to enhance yields as compared to nutrient controls, with a recognized role for manganese and calcium in the lectin cycle. Lectins have roles in the carbon reactions of photosynthesis, the sugar code and cell signaling, and ongoing studies of the plant lectome may lead the field toward glycomimetics, molecules that emulate the structure and function of natural glycans, which the authors suggest could improve the efficiency of photosynthesis. The authors recommend further investigations, especially for cultivated plants, by means of biocuration and genetic tools including transcriptomics, metabolomics, proteomics, genomics, epigenomics, ionomics and lipidomics, seeking information about the specificity of metalloenzymes to corresponding organelles such as chloroplasts, peroxisomes and vacuoles. They also point to silicon as a beneficial mineral whose interactions with photorespiration and with essential and beneficial elements may indicate a critical role. For now, the message is clear: photosynthesis depends on the presence of essential mineral elements at their sites of action, for the most part in the leaves and green stems of crop plants, and securing their sufficiency is inseparable from securing the energy transformation on which all green plants, and the food systems built upon them, ultimately rely.

Subject of Research: The roles of essential nutrient elements in the light and carbon reactions of photosynthesis

Article Title: The essential nutrient elements in photosynthesis

Article References: Shevela, D., & Nonomura, A. (2026). The essential nutrient elements in photosynthesis. Frontiers in Photobiology, 4, Article 1817712. https://doi.org/10.3389/fphbi.2026.1817712

Image Credits: AI Generated

DOI: 10.3389/fphbi.2026.1817712

Keywords: photosynthesis, essential nutrients, mineral nutrition, chloroplast, Photosystem II, Photosystem I, macronutrients, micronutrients, metalloproteins, electron transport, crop productivity, plant signaling

The scale of the problem is staggering. The review reports that roughly 4.8 to 12.7 million metric tons of plastic enter the oceans annually, while approximately 12.5 million metric tons of plastic waste have been dumped on land, with agricultural soils receiving an estimated 23 times more microplastic load than oceanic environments. Global plastic production reached 367 million metric tons in 2020, and a substantial share of that material ends up in fields through mulching films, plastic greenhouses, irrigation pipes, sewage sludge, and organic composts. The authors estimate that microplastic concentrations in soil can reach up to 67,500 particles per kilogram in some agricultural settings, with mulch films alone contributing between 10 and 30 kilograms of plastic debris per hectare each year.

Once in the soil, microplastics do not simply sit inert. The review documents how these particles alter the physical architecture of soil, changing bulk density, water retention, and the stability of aggregates that hold the soil together. They can leach toxic additives such as phthalates, bisphenol A, and heavy metals, and they interact with earthworms, fungi, and the vast microbial communities that drive nutrient cycling. Studies cited in the review show that microplastic exposure can reduce bacterial and fungal diversity, disrupt enzymatic activity, and impair the nitrogen and carbon cycles that crops depend on. Earthworms, the engineers of healthy soil, have been shown to suffer reduced growth and reproduction when exposed to microplastic-laden soils, with some experiments reporting declines in earthworm survival and changes in their burrowing behavior.

Perhaps the most alarming finding concerns how microplastics make their way into the plants themselves. The review details evidence that nanoparticles and small microplastic particles can cross the root barrier and travel through vascular tissues, accumulating in stems, leaves, and even edible organs such as grains and fruits. Studies on lettuce, carrots, and apples have detected microplastic particles in plant tissues, with lettuce showing uptake of nanoplastic particles through roots and apples containing microplastics in their flesh. The mechanisms involve apoplastic and symplastic pathways, where particles slip between cell walls or are actively transported through cellular machinery, though larger particles tend to remain trapped at the root surface or in the root cap.

The consequences for crop physiology are measurable and often negative. The review summarizes experiments showing that microplastic exposure can reduce seed germination rates, stunt root and shoot growth, and interfere with photosynthesis. In wheat, exposure to polyethylene and polystyrene microplastics has been linked to reduced plant height and biomass, while in rice and maize, microplastic contamination has been associated with decreased chlorophyll content and disrupted photosynthetic efficiency. Some studies report yield losses of up to 30 percent under high microplastic concentrations, though the review notes that results vary widely depending on particle type, size, concentration, and crop species. The mechanisms include physical damage to root cells, oxidative stress from reactive oxygen species, and interference with nutrient and water uptake.

Beyond the plants themselves, microplastics threaten the broader agricultural ecosystem. The review highlights how these particles can alter soil microbial communities in ways that reduce the effectiveness of beneficial symbioses, such as the mycorrhizal fungi that help plants absorb phosphorus and water. They can also serve as vectors for antibiotic resistance genes, creating reservoirs of drug-resistant bacteria in agricultural soils. The combination of microplastic contamination with other stressors, including heavy metals, pesticides, and climate change, creates a compounding threat that the authors argue has been largely overlooked in conventional risk assessments.

The human health dimension adds urgency to these findings. Microplastics have now been detected in human blood, lungs, placenta, and breast milk, and the review cites studies suggesting that humans may ingest tens of thousands of microplastic particles annually through food and water. While the full health consequences remain uncertain, preliminary research links microplastic exposure to inflammation, oxidative stress, and potential disruption of endocrine function. The review notes that microplastics in food crops represent a direct exposure pathway that bypasses environmental dilution, making agricultural contamination a matter of food safety as well as environmental concern.

The authors also examine potential solutions, though they acknowledge that most remain in early stages. Biodegradable mulch films made from starch, cellulose, or polylactic acid offer a promising alternative to conventional polyethylene, though their performance and cost remain barriers to widespread adoption. Bioremediation approaches, including the use of plastic-degrading microbes and enzymes, show laboratory promise but face significant challenges in real-world soil environments. Policy interventions, such as restrictions on single-use plastics and improved waste management, could reduce the flow of microplastics into agricultural systems, but the authors note that existing regulations are fragmented and often poorly enforced.

The review calls for urgent interdisciplinary research to address the knowledge gaps that currently limit effective action. The authors identify several priorities, including standardized methods for measuring microplastics in soil and food, long-term field studies that track the fate of microplastics under realistic agricultural conditions, and investigations into the combined effects of microplastics with other environmental stressors. They also emphasize the need for better understanding of how microplastics interact with soil biota at the molecular level, particularly in the rhizosphere where roots, microbes, and soil particles interact in complex ways.

Ultimately, the review paints a picture of an agricultural system quietly accumulating a form of pollution that threatens its own productivity and the safety of the food it produces. The authors conclude that addressing microplastic contamination in agricultural soils requires coordinated action across research, policy, and practice, and that the window for preventing widespread, irreversible contamination may be narrowing. As plastic production continues to grow and agricultural intensification accelerates, the invisible burden of microplastics in the world’s farmland is set to increase, making this one of the most pressing yet underappreciated environmental challenges of the coming decade.

Subject of Research: Microplastic contamination of agricultural soils and its effects on soil health, crop productivity, and food safety

Article Title: Microplastics in agricultural soils: sources, soil–plant interactions, ecotoxicological effects and food security concerns

Article References: Rustagi, D., Kunal, Kumar, R., Kumar, P., Kumar, A., Rajeev, Critykar, J., Mitra, D., Gautam, M. K., Rajput, V. D., & Babatunde, C. A. (2026). Microplastics in agricultural soils: sources, soil–plant interactions, ecotoxicological effects and food security concerns. Frontiers in Soil Science, 6, Article 1899490. https://doi.org/10.3389/fsoil.2026.1899490

Image Credits: AI Generated

DOI: 10.3389/fsoil.2026.1899490

Keywords: microplastics, agricultural soils, crop productivity, food security, soil health, plant uptake, mulch films, bioremediation, food safety, soil microbiome, environmental pollution, sustainable agriculture

The case for alternatives to conventional fertilizers rests on well-documented problems. Chemical fertilizers deliver nutrients quickly and in concentrated form, which is precisely why they dominate modern agriculture, but their overuse has disturbed ecological balance, contributed to environmental pollution, and become increasingly unaffordable for many farmers. The review notes that synthetic fertilizers, pesticides, and herbicides are among the principal drivers of environmental contamination worldwide. By contrast, biofertilizers work more slowly but more gently: they convert nutrients that plants cannot access into forms they can, gradually enriching the soil rather than depleting it. Reported yield gains from microbial inoculants range from 10 to 40 percent, and after three to four years of continuous use, the introduced microbial populations can sustain themselves, reducing the need for repeated applications.

At the heart of the review is a detailed taxonomy of the microbial workhorses involved. Nitrogen-fixing biofertilizers, including symbiotic bacteria from the Rhizobiaceae family such as Rhizobium, Bradyrhizobium, and Sinorhizobium, reside in legume root nodules and can fix 50 to 100 kilograms of nitrogen per hectare, boosting legume yields by 10 to 35 percent. Free-living fixers like Azotobacter and Azospirillum, along with nitrogen-fixing cyanobacteria, extend these benefits to non-leguminous crops; in rice systems, biological nitrogen fixation combined with soil organic matter mineralization is estimated to meet 50 to 60 percent of the crop’s nitrogen requirement. Phosphate-solubilizing bacteria from genera such as Pseudomonas, Bacillus, and Burkholderia tackle a different bottleneck: roughly 95 to 99 percent of soil phosphorus exists as insoluble phosphates that plants cannot use, and these microbes release it through localized acidification and organic acid secretion.

The review extends this catalog to nutrients that receive less attention. Potassium-mobilizing bacteria such as Bacillus mucilaginosus dissolve mineral sources like micas, illite, and orthoclase, improving enzyme activation, photosynthesis, and disease resistance in crops. Sulfur-oxidizing bacteria, including Thiobacillus species, have been shown to improve plant growth in calcareous and saline soils by increasing nutrient accessibility. Zinc-solubilizing microbes address a micronutrient deficiency that causes chlorosis, smaller leaves, and heightened stress susceptibility, while silicate-solubilizing bacteria such as Bacillus megaterium and Pseudomonas fluorescens release silicon from abundant but insoluble crustal minerals, benefiting high silicon-accumulating species under unfavorable conditions. Siderophore-producing bacteria, meanwhile, chelate insoluble ferric iron and deliver it to plant roots, supporting photosynthesis and chlorophyll production.

Perhaps the most biologically intricate section concerns the dialogue between plants and microbes. Roots exude a chemical cocktail of sugars, amino acids, organic acids, vitamins, and phenolic compounds that act as chemo-attractants, guiding beneficial bacteria toward the root surface. A two-step acquisition model describes how microbes first pass through membrane and cell-wall recognition filters and are then further selected by host genetic traits. Recent comparative genomic work suggests that traits related to carbon and nitrogen acquisition, rather than auxin production, determine which strains successfully colonize the rhizosphere. Quorum sensing allows bacteria to coordinate their activities in response to environmental conditions, and multi-omics analyses have revealed that nitrogen fixation genes, phosphate transporters, and ACC deaminase genes are upregulated in the rhizosphere within 48 to 72 hours of root contact—a remarkably rapid functional activation that opens the door to predictive, mechanism-based inoculant design.

Beyond nutrition, the review documents biofertilizers’ role as stress-mitigation agents, an increasingly urgent function as climate change intensifies drought, salinity, and heat. Arbuscular mycorrhizal fungi, which form mutualistic symbioses with about 80 percent of land plant species, produce glomalin, a glycoprotein that aggregates soil particles and retains water. The endophytic fungus Piriformospora indica confers tolerance to salinity and systemic diseases in barley, while Pseudomonas fluorescens has alleviated drought stress in crops by promoting growth under water-limited conditions. Plant growth-promoting rhizobacteria that produce ACC deaminase metabolize the ethylene precursors plants generate under heavy metal stress, and the mycorrhizal fungus Glomus intraradices has improved photosynthetic efficiency and antioxidant defenses in drought-stressed rice. Nitrogen-fixing Rhizobium strains from coastal regions have even enhanced productivity in saline soils.

The authors are refreshingly candid about why biofertilizers so often disappoint in the field. A meta-analysis cited in the review found that biofertilizers increased crop yields by an average of 12 to 18 percent across more than 200 studies, but the coefficient of variation exceeded 40 percent, and in roughly a quarter of field trials the inoculants had no significant effect at all. Strains that boosted wheat yields by 25 percent in greenhouse pots managed only 0 to 8 percent across twelve field locations, largely because introduced bacteria cannot compete with native rhizosphere communities—colonization rates plummet from over 10^8 cells per gram of root in sterile conditions to under 10^4 in natural soil. High native soil nitrogen, low pH, heavy clay content, and temperatures above 35 degrees Celsius all suppress performance, and these constraints rarely appear on commercial product labels.

The futuristic toolkit described in the review aims to close that gap. Nano-biofertilizers encapsulate microbes in chitosan, alginate, or other polymer nanoparticles that protect them from desiccation, ultraviolet radiation, and heat while releasing nutrients in synchrony with plant demand; nano-encapsulated Rhizobium cells have remained viable for six months at 40 degrees Celsius, compared with two weeks for free cells. CRISPR-edited strains of Azospirillum and Pseudomonas have outperformed wild types in proof-of-concept studies, with targets including nitrogenase regulation, ACC deaminase overexpression, and enhanced biofilm formation. Machine learning models trained on metagenomic, climate, and yield datasets can predict which strain-host-environment combinations will succeed, potentially cutting screening time and costs by 60 to 70 percent, while synthetic communities combining complementary functions have shown improved root colonization and more consistent field performance than single-strain inoculants.

The review closes with a reminder that technology alone will not transform agriculture. Pilot programs in India, Brazil, and Kenya show that farmer training combined with subsidized starter kits raised adoption rates from below 10 percent to 40 percent within three to five years, suggesting that decentralized production, quality certification, and digital extension tools matter as much as laboratory breakthroughs. Circular-economy approaches that convert municipal waste, crop residues, and animal manure into biofertilizer formulations with viable counts exceeding 10^8 cells per gram offer the dual benefit of waste remediation and affordable farm inputs. If formulation stability, regulatory frameworks, and farmer knowledge advance in step with the underlying microbiology, the authors conclude, biofertilizers could become a cornerstone of climate-resilient farming—quietly, microbially, and at a fraction of the environmental cost of the chemicals they are meant to complement.

Subject of Research: The role of microbial biofertilizers in enhancing crop productivity, soil health, and environmental sustainability in modern agriculture

Article Title: Optimizing crop productivity and environmental sustainability through biofertilizer application in modern farming systems

Article References: Khan, M. H., Islam, S. M. M., Islam, M. N., Naher, U. A., Tarannum, F., Jannaty, M. J., Islam, T., Debnath, R. R., Zubayer, M., Akter, M., & Islam, M. R. (2026). Optimizing crop productivity and environmental sustainability through biofertilizer application in modern farming systems. Discover Soil, 3(1), Article 166. https://doi.org/10.1007/s44378-026-00326-6

Image Credits: AI Generated

DOI: 10.1007/s44378-026-00326-6

Keywords: biofertilizers, sustainable agriculture, soil fertility, nitrogen fixation, plant growth-promoting rhizobacteria, mycorrhizal fungi, nano-biofertilizers, phosphate solubilization, environmental stress, crop productivity, microbial consortia, synthetic fertilizers

Biofertilizers are formulations of living microorganisms, including nitrogen-fixing bacteria, phosphate-solubilizing microbes, and mycorrhizal fungi, that colonize the rhizosphere and help plants acquire nutrients that would otherwise remain locked in soil minerals or the atmosphere. Unlike synthetic fertilizers, which deliver nutrients in chemically available form but can contribute to greenhouse gas emissions, water pollution, and long-term soil degradation, biofertilizers work by augmenting the soil’s own biological machinery. Their appeal has grown as India, like much of the world, confronts the twin pressures of feeding a rising population and reducing the environmental footprint of agriculture, a sector that is a major driver of several planetary boundaries being exceeded.

To quantify the joint effects of these microbial inputs, the research team, led by Dinesh Chand Meena of ICAR-National Institute of Agricultural Economics and Policy Research in New Delhi, applied the rigorous statistical machinery of modern meta-analysis. Effect sizes were calculated using the natural logarithm of the response ratio, a standard metric in experimental ecology that expresses the proportional change between treated and untreated plots. Mixed-effects models were then used to estimate overall and subgroup responses across biofertilizer types, crop categories, soil types, and agro-climatic zones, while heterogeneity among studies was assessed with the I-squared statistic and the Q-test at a significance threshold of p less than 0.05. This framework allowed the researchers to distinguish consistent, generalizable patterns from the noise inherent in hundreds of individually small field trials.

The headline finding was a robust average yield gain of 14.43 percent, but the subgroup analysis revealed a more nuanced picture. Mixed inoculants, products combining several microbial strains, outperformed single-strain formulations, suggesting that complementary microbial functions, such as simultaneous nitrogen fixation and phosphorus solubilization, deliver synergistic benefits. Among single inoculants, Azospirillum, a genus of plant-associated bacteria best known for biological nitrogen fixation but increasingly recognized for hormone production and root growth promotion, showed the strongest yield response at 16.8 percent. The result aligns with a growing body of work indicating that Azospirillum’s benefits extend well beyond simply adding nitrogen to the plant-soil system.

Crop type mattered considerably. Horticultural crops responded more strongly than field crops, with fruits showing an average yield increase of 18.93 percent and vegetables 16.61 percent. This pattern is consistent with the biology of high-value, intensively managed systems, where root-zone conditions and nutrient demand favor microbial activity. Soil texture also emerged as a decisive variable: loamy soils, with their balanced mixture of sand, silt, and clay, showed the largest positive response at 17.65 percent, likely because their structure supports both moisture retention and the aeration that beneficial microbes require. The findings imply that blanket recommendations for biofertilizer use may be less effective than targeted strategies matched to crop and soil context.

Beyond yields, the analysis documented substantial improvements in the soil itself. Biofertilizer use increased soil nutrient availability by more than 16 percent, reflecting enhanced mobilization of nitrogen, phosphorus, and potassium, and raised soil organic carbon by 5.76 percent. That carbon figure is particularly significant in the context of climate policy, because soil organic carbon is both a key indicator of soil fertility and a reservoir for carbon sequestration. Previous meta-analyses have similarly found that biofertilization raises soil organic carbon concentrations, and long-term field studies in India and China have linked sustained microbial inoculation with improved aggregate stability and carbon storage. The new analysis consolidates this evidence for Indian conditions, where land degradation affects a substantial share of the cultivated area.

Perhaps the most distinctive contribution of the study is its economic dimension. The researchers estimated the total economic value of the ecosystem services associated with biofertilizer use, reaching USD 133.15 per hectare in field crops and USD 239.81 per hectare in horticultural crops. Strikingly, non-market ecosystem services, benefits such as soil formation, nutrient cycling, and carbon storage that do not pass through any market and therefore go unpriced in conventional farm accounting, contributed up to 43 percent of the total value in field cropping systems. This means that nearly half of what biofertilizers deliver to society is invisible in standard yield-and-price calculations, a blind spot that has historically led to the underprovision of practices with large public benefits.

The valuation approach reflects a broader shift in agricultural economics toward recognizing farms as providers of ecosystem services rather than commodities alone. Frameworks for integrating ecosystem service values into landscape planning and decision-making have matured over the past decade, and national bodies in India have begun exploring payments for ecosystem services in agriculture. By attaching concrete dollar figures to the soil health and carbon benefits of biofertilizers, the new analysis gives policymakers a defensible basis for subsidy design, incentive schemes, and climate finance proposals that reward farmers for outcomes beyond raw production. It also helps explain why adoption of biofertilizers has lagged despite their low cost: farmers capture only the market-priced fraction of the benefits, while the rest accrues to society at large.

The study’s authors frame biofertilizers as a scalable pathway toward climate-resilient, Sustainable Development Goal-aligned agricultural development, provided that appropriate policy support is in place. That caveat matters. Meta-analyses of other sustainable intensification practices, from conservation agriculture to integrated nutrient management, have shown that average benefits can mask substantial variability and that adoption barriers, including input quality, farmer knowledge, and supply chains, often determine real-world outcomes. The inherent difficulties of developing soil microbial inoculants, including strain selection and consistency across environments, remain active research challenges. Still, the sheer weight of evidence assembled here, more than two thousand paired observations spanning crops, soils, and agro-climatic zones, makes a compelling case that microbial inputs can deliver productivity and environmental gains together rather than as a trade-off.

For a world grappling with slowing agricultural productivity growth under climate change, rising fertilizer costs, and mounting pressure to cut emissions, the message is timely. Biofertilizers will not replace synthetic fertilizers outright, and their performance is context-dependent, strongest in loamy soils and horticultural systems, and enhanced when multiple strains are combined. But the analysis suggests that integrating them intelligently into nutrient management could raise yields by double digits, rebuild soil carbon, and generate hundreds of dollars per hectare in societal value, much of it currently uncounted. As governments search for win-win interventions in the race to make food systems sustainable, the smallest players in the field, the microbes in the soil, are proving to be among the most consequential.

Subject of Research: The effects of biofertilizers on crop productivity, soil ecosystem services, and their economic valuation in Indian agriculture

Article Title: Effects of biofertilizers on crop productivity and soil ecosystem services: a meta-analysis

Article References: Meena, D. C., Meena, V. S., Kumari, M., & Sharma, I. (2026). Effects of biofertilizers on crop productivity and soil ecosystem services: a meta-analysis. Clean Technologies and Environmental Policy, 28(10), Article 247. https://doi.org/10.1007/s10098-026-03597-3

Image Credits: AI Generated

DOI: 10.1007/s10098-026-03597-3

Keywords: biofertilizers, crop productivity, soil health, ecosystem services, meta-analysis, soil organic carbon, sustainable agriculture, Azospirillum, economic valuation, carbon sequestration, Indian agriculture, soil fertility

The analysis began with the Scopus database, where an initial search for biochar literature returned more than 50,000 documents. After filtering for work connected to carbon farming and the Mediterranean basin, the researchers retained 112 publications for detailed evaluation, mapping the field’s networks with VOSviewer software and adopting a structured narrative review approach. Their central finding is both encouraging and cautionary: biochar consistently builds soil carbon stocks and generally reduces nitrous oxide emissions, but its benefits for crops appear only when it relieves a genuine limitation, such as drought, salinity, or degraded soil structure. Applied indiscriminately to healthy, non-stressed fields, it may deliver little gain, or even cause harm.

The technical foundation of biochar’s appeal lies in pyrolysis, a thermal decomposition process conducted under oxygen-limited conditions at temperatures ranging from 300 to 1000 degrees Celsius. Slow pyrolysis, fast pyrolysis, and gasification each yield materials with distinct physicochemical properties. Higher-temperature biochars, produced at or above 600 to 700 degrees Celsius, are richer in aromatic carbon, more structurally stable, and more porous, making them exceptional long-term carbon vaults. Lower-temperature biochars retain more labile compounds and oxygen-containing functional groups that boost short-term nutrient availability and cation exchange capacity. Feedstock matters too: manure-derived biochars carry higher nutrient and ash content, while lignocellulosic materials from straw and wood produce denser, more porous, more persistent carbon structures.

Unlike compost or other conventional organic amendments, which soil microbes decompose within seasons, biochar’s pyrogenic carbon resists breakdown for centuries, with estimated mean residence times ranging from several hundred years to more than a millennium. Global meta-analyses cited in the review indicate that biochar application raises soil organic carbon stocks by an average of roughly 39 percent, and Mediterranean field studies confirm consistent accumulation even under the region’s punishing wet-dry cycles. Notably, one cited study demonstrated that biochar-induced increases in soil organic matter pools were not significantly altered by simulated climate change scenarios, suggesting that the stored carbon would survive the hotter, drier Mediterranean of the coming decades. Biochar can also slow the decomposition of existing soil organic matter through negative priming, adding a second layer of protection to carbon already in the ground.

On greenhouse gases, the picture is nuanced and, in one respect, troubling. Mediterranean field experiments generally report neutral or reduced carbon dioxide emissions after biochar application, confirming that the amended carbon is not being rapidly re-released, and reductions in nitrous oxide, a greenhouse gas nearly 300 times more potent than carbon dioxide, of 30 to 70 percent have been documented. The mechanism involves adsorption of ammonium and nitrate ions, which starves nitrifying and denitrifying microbes of substrate, alongside improved soil aeration that suppresses the anaerobic microsites where denitrification thrives. Mitigation is particularly pronounced when biochar is paired with organic fertilizers or digestates, stabilizing labile carbon inputs that would otherwise fuel microbial activity.

Methane, however, is the review’s warning flag. Several long-term Mediterranean field studies recorded increased methane emissions following biochar application, especially during warm, moist autumn and winter conditions. The culprit is the formation of biologically induced anaerobic microsites within biochar’s pore network when soils become water-saturated, creating localized oxygen-free pockets that favor methanogenic archaea. Emissions rose in proportion to application rate in at least one study, exposing a stark trade-off between maximizing carbon sequestration and minimizing greenhouse gas losses. The authors conclude that moderate application rates, generally 10 to 30 megagrams per hectare, represent the sweet spot, and that net climate assessments excluding methane risk seriously overestimating biochar’s mitigation value, particularly in fine-textured or poorly drained soils.

Crop responses vary sharply by species and growing condition. Among cereals, durum wheat has benefited from biochar through improved water retention during grain filling and enhanced nitrogen and phosphorus availability, though some controlled studies found reduced early shoot growth when biochar was applied without complementary nutrients. Rice shows consistent gains when biochar is combined with sprinkler or deficit irrigation, boosting yields, photosynthesis, and water-use efficiency while easing the transition away from flooded production. Maize responds strongly in saline soils, where biochar curbs sodium uptake and preserves potassium, but medium-term trials under non-stress conditions reported negligible yield gains despite measurable soil improvements, reinforcing the principle that soil chemistry alone does not guarantee agronomic return.

Legumes and perennial woody crops emerge as the stars of the analysis. Fenugreek, faba bean, and cowpea all showed improved yields, chlorophyll content, antioxidant activity, and stress tolerance, likely because biochar enhances phosphorus availability and rhizosphere conditions that support biological nitrogen fixation. In vineyards, a single biochar application improved vine water status, stomatal conductance, and drought resilience for more than a decade, a persistence that dramatically improves cost-effectiveness. Super-intensive olive groves treated with biochar from olive residues showed higher soil moisture, net photosynthesis, water-use efficiency, and fruit yield even under deficit irrigation. Vegetables tell a more mixed story: tomato and pepper respond reliably well, melon and zucchini benefit when biochar is combined with digestate or compost, while lettuce and onion have suffered yield losses in volcanic Mediterranean soils, apparently due to nutrient imbalances and phytotoxic compounds. Peach trees showed reduced survivability despite normal yields among surviving plants, underscoring the need for species-specific testing before large-scale deployment.

The review’s authors argue that biochar should be deployed selectively, targeting degraded or coarse-textured soils, water-limited or saline fields, and long-lived perennial systems such as orchards and vineyards, rather than applied uniformly across the landscape. They call for long-term, crop-centered field experiments to validate yield persistence and net greenhouse gas balances, with particular attention to methane mitigation strategies and underexplored systems like legumes and diversified rotations. Beyond the agronomy, economics will decide adoption: feedstock collection, pyrolysis processing, transport, and field application are costly in a region marked by fragmented landownership and limited infrastructure, while carbon credit markets remain uncertain and unevenly supported across Mediterranean countries. If pricing frameworks mature and decision-support tools reach farmers, the researchers conclude, biochar could convert the Mediterranean’s agricultural waste streams into a durable bridge between food production and climate stabilization, provided the methane caveat is heeded every step of the way.

Subject of Research: The role of biochar in carbon farming and climate-smart Mediterranean agroecosystems

Article Title: Carbon farming strategies for mediterranean agriculture: the role of biochar in climate-smart agroecosystems

Article References: Borgatti, D., Radicetti, E., Mancinelli, R., Coluccia, L., Allam, M., Jamal, A., Abideen, Z., Ahsan, M., & Hassine, M. B. (2026). Carbon farming strategies for mediterranean agriculture: the role of biochar in climate-smart agroecosystems. Crop Health, 4(1), Article 19. https://doi.org/10.1007/s44297-026-00081-8

Image Credits: AI Generated

DOI: 10.1007/s44297-026-00081-8

Keywords: biochar, carbon farming, Mediterranean agriculture, carbon sequestration, greenhouse gas emissions, nitrous oxide, methane, soil health, climate-smart agriculture, crop productivity, pyrolysis, sustainable agriculture