The experiment was conducted at the Training and Experimental Station of the Agricultural University of Plovdiv in southern Bulgaria. The site had a Mollic Fluvisol with an initial total organic carbon content of 1.14%, a slightly alkaline pH of 8.22, low available nitrogen, and comparatively high phosphorus and potassium. Thirty barley plots were arranged in a randomised complete block design, with three replicates per treatment.

In spring 2022, the researchers established two prior cropping systems: monocultured oats and an intercrop of oats and common vetch sown at a 3:1 vetch-to-oats ratio, for a total of 220 kg/ha. Oat monoculture biomass was harvested, while the oat–vetch biomass was ploughed into the soil as green manure to a depth of 30 cm. Winter barley was then planted in November 2022. Each cropping system received an unfertilised control, mineral NPK fertiliser at 100 kg/ha, vermicompost at 12 t/ha, half-rate mineral fertiliser plus vermicompost, or biochar at 10 t/ha.

Rhizosphere soil was collected from randomly selected barley plants at ripening in 2023. Samples were kept on ice during transport, sieved to 2 mm and stored at –80 °C before DNA extraction. The authors used 16S rRNA gene amplicon sequencing and bioinformatic analysis of ten samples. Reads underwent quality control, merging and chimera removal before inference of amplicon sequence variants and taxonomic assignment against SILVA v138. Sequencing quality was high: all samples exceeded 98% at Q20 and 95% at Q30, while Good’s coverage ranged from 0.998 to 1.000.

Proteobacteria, Actinobacteriota and Acidobacteriota dominated at the phylum level across the treatments. Vermicompost and combined mineral–vermicompost treatments had relatively elevated Actinobacteriota and Bacteroidota, while mineral-fertilised and unfertilised soils had relatively higher Acidobacteriota proportions. Biochar produced a comparatively distinct profile, including slightly higher Verrucomicrobiota and Chloroflexi. At genus level, Sphingomonas was consistently prominent, while green-manure and organic-amendment treatments showed enrichment of genera including Nocardioides, Agromyces, Rubrobacter, Solirubrobacter and Noviherspirillum.

Alpha-diversity measurements also varied among treatments. VC2, grown without green manure and treated with vermicompost, recorded the highest Chao1 richness at 2,868.429, narrowly ahead of VC1, which followed the oat–vetch green manure, at 2,864.731. VC2 also had the highest Shannon index at 10.572 and a Pielou evenness of 0.921. By comparison, the combined mineral–vermicompost treatments had lower richness values of 2,406.176 for MF1.VC1 and 2,379.850 for MF2.VC2, while Bch2 recorded 2,315.000. A treatment-comparison analysis identified 363 taxa shared across treatments. The largest numbers of treatment-specific taxa occurred in VC2, with 837, and VC1, with 779.

Community-composition analyses indicated that individual treatments occupied different positions in PCA and PCoA space. Bch1, VC2 and the MF2.VC2 treatment were relatively separated from several other groups, whereas Control1, MF1 and VC1 clustered more closely. Pairwise Bray–Curtis and UniFrac distances were also greatest for comparisons involving Bch2. These ordination and distance results show differences in the observed bacterial assemblages among treatments; the supplied results do not report the outcomes of the planned ANOSIM or PERMANOVA group comparisons.

The findings associate the preceding oat–vetch green manure with a legacy in the barley rhizosphere bacterial community. The study’s authors interpret the enrichment of degradative and nitrogen-cycling taxa under green manure and organic-input treatments as evidence that these practices may support broader microbial diversity and potential functional redundancy. They also report that mineral fertiliser alone was associated with comparatively lower diversity in some comparisons. These functional interpretations remain indirect because the analysis was based on bacterial community composition and inferred ecological roles rather than direct measurements of nutrient turnover, disease suppression or barley growth.

The experiment has several bounded limitations. It was conducted at one Bulgarian field site over a two-year rotation, with 16S data from ten samples representing the broader set of 30 plots, and it examined bacteria rather than fungi, protozoa or the complete soil food web. The study therefore shows treatment-associated shifts in the barley rhizosphere bacteriome, not demonstrated improvements in crop yield, soil fertility or farm performance. The authors note that broader metagenomic work incorporating fungal and protozoan contributions would be needed to assess the wider microbial community.

Subject of Research: A 2023 Bulgarian field study of how fertilisation and an oat–vetch green-manure legacy affected winter barley rhizosphere bacterial communities.

Article Title: Barley Rhizosphere Bacteriome Dynamics under Organic and Mineral Inputs: The importance of intercropping predecessor

Article References: Shilev, S., Petkova, M., Popova, V., Neykova, I., & Rangelov, I. (2025). Barley Rhizosphere Bacteriome Dynamics under Organic and Mineral Inputs: The importance of intercropping predecessor. Metabarcoding and Metagenomics, 9, Article e167231. https://doi.org/10.3897/mbmg.9.167231

Image Credits: AI Generated

DOI: 10.3897/mbmg.9.167231

Keywords: barley rhizosphere, bacterial communities, 16S rRNA sequencing, oat–vetch intercropping, green manure, vermicompost, biochar, mineral fertiliser, soil microbiome, field experiment, Barley, Rhizosphere

Researchers established randomized complete block trials at Ntengo-wa-Mbalame in Tsangano, Rinze in Angónia and the CITTA Research Centre during the 2022/23 and 2023/24 growing seasons. Each site included 11 treatments with three replications, and plants were destructively sampled at 28, 40, 70 and 120 days after planting. These sampling points represented vegetative growth, tuber initiation, tuber bulking and physiological maturity, allowing the investigators to follow nutrient accumulation rather than relying only on an end-of-season comparison. The potatoes were cv. Mondial, planted at 41,666 plants per hectare, while zinc and copper sulfate were applied uniformly to prevent micronutrient deficiencies.

The soils were acidic, with calcium chloride pH values of 5.4 at Ntengo-wa-Mbalame and 4.6 at both Rinze and CITTA. The experimental sites included Chromic Abruptic Alisols, Chromic Luvisols and Pellic Calcic Vertisols, and the authors identified potential aluminum toxicity and strong phosphorus fixation as central challenges. Against that background, the most closely matched treatment, T7, supplied 60 kilograms of mineral nitrogen per hectare, 1.9 tonnes of vermicompost per hectare, and Bio-Rock P containing Minjingu rock phosphate inoculated with strains of K. variicola. It also included mineral potassium and sulfur, with phosphorus supplied through the inoculated rock phosphate. Full mineral fertilization supplied 120 kilograms of nitrogen, 92 kilograms of P₂O₅, 120 kilograms of K₂O and 45 kilograms of sulfur per hectare.

Vermicompost made from maize and soybean residues, cattle manure and vermicomposting by Eisenia foetida was incorporated seven days before planting. Bio-Rock P was placed in planting holes at planting, and half of the mineral nitrogen was incorporated at planting while the remainder was applied 30 days later. In laboratory assays, the two bacterial strains produced available phosphorus concentrations of 159.81 and 218.81 milligrams per liter in calcium phosphate assays at pH 4.51 and 3.99, respectively, compared with 0.098 milligrams per liter in the control. With Minjingu rock phosphate, recovered phosphorus reached 55.86 and 49.35 milligrams per liter, exceeding the control’s 29.09 milligrams per liter. These laboratory results supported the biological component of the field treatment but were not themselves evidence of field yield gains.

Nutrient accumulation generally followed quadratic curves with coefficients of determination around 0.95, although the authors emphasized that the estimated peaks were model-based because only four sampling dates were available. In the more favorable first season, modeled maximum nitrogen and potassium accumulation generally occurred about 98 to 115 days after planting. Estimated phosphorus peaks occurred between 108 and 113 days after planting at two sites. Potassium had the greatest modeled peak magnitude, reaching 10.23 grams per plant at CITTA in the first season. T7 consistently belonged to the highest statistical group for nutrient accumulation and achieved nitrogen and phosphorus recovery efficiencies statistically equivalent to the complete mineral treatment, showing that the integrated package maintained nutrient acquisition under the conditions tested.

Secondary macronutrients and micronutrients also responded to the integrated treatments. Modeled calcium, magnesium and sulfur peaks ranged from 77.5 to 121.4 days after planting, depending on site, nutrient and season. T7 and T8 ranked in the highest statistical group for calcium, with estimated peaks as high as 1.20 grams per plant, and for sulfur, with peaks reaching 0.27 grams per plant. Iron showed the largest micronutrient accumulation, including an estimated first-season peak of 165.49 milligrams per plant at CITTA. Copper was unusual because its accumulation followed a linear pattern at nearly all sites and seasons, with a detectable inflection point only at Ntengo in the second season. The authors cautioned that uniform copper-based fungicide use may have contributed to measured copper through surface contamination rather than plant uptake alone.

Seasonal conditions strongly altered the results. Analysis of variance identified effects of year, treatment and growth stage, as well as interactions between year and treatment and between year and stage. Across the sites, nutrient accumulation in the first season was 35% to 45% greater than in the second. Rainfall and temperature patterns were associated with greater late-blight pressure from Phytophthora infestans in the second season, when fungicide applications were increased to weekly intervals. Because disease incidence and severity were not quantitatively measured, the statistical analysis could not directly quantify late blight as an explanatory variable. Nevertheless, total biomass was lower at the final sampling, and fitted nitrogen and potassium peaks at Ntengo occurred earlier, at about 87 days after planting, rather than beyond 110 days.

The study also evaluated apparent recovery efficiency, agronomic efficiency, physiological efficiency and internal utilization efficiency for nitrogen and phosphorus, then combined these measures with yield through principal component analysis. The first two components explained 68.55% of total variation in the first season and 65.29% in the second. In the second season, internal nitrogen efficiency increased from 342.02 to 460.68 kilograms per kilogram as absolute accumulation declined. The authors interpreted this as possible preferential partitioning of absorbed nutrients toward tubers under stress, but cautioned that the earlier fitted peaks could partly be mathematical artifacts of reduced biomass at 120 days. A separate potassium peak of 127.4 days after planting at CITTA in the second season was explicitly an extrapolation beyond the experiment and was not an observed maximum.

For farmers, the practical significance of the findings is that nutrient supply from vermicompost and biologically mobilized rock phosphate can be combined with reduced mineral nitrogen without measurably compromising nutrient acquisition relative to full mineral fertilization in these trials. The authors also argue that such combinations could lower dependence on costly mineral inputs, although the experiment did not provide a complete economic assessment of treatment profitability. The approach should not be read as a recommendation that fertilizer applications can be reduced indiscriminately: T7 remained a balanced package that included mineral potassium and sulfur, and its performance depended on local soil conditions, rainfall, crop management and disease pressure. Future work should use denser sampling intervals, larger plots, additional locations and seasons, and longer-term measurements of soil carbon and microbial communities. Until then, the strongest conclusion is that the tested integrated treatment can match full mineral nutrient acquisition in acidic tropical highlands while supplying nutrients through complementary biological, organic and mineral pathways.

Subject of Research: Integrated mineral, organic and microbial fertilization for nutrient uptake in acidic-soil potato cultivation

Article Title: Sustainable intensification of potato production: nutrient uptake kinetics and accumulation dynamics under integrated fertilization in acidic tropical highlands

Article References: Sande, T. J., Alovisi, A. M. T., Tindwa, H. J., Semoka, J. M., & Shitindi, M. (2026). Sustainable intensification of potato production: nutrient uptake kinetics and accumulation dynamics under integrated fertilization in acidic tropical highlands. Frontiers in Agronomy, 8, 1980417. https://doi.org/10.3389/fagro.2026.1980417

Image Credits: AI Generated

DOI: 10.3389/fagro.2026.1980417

Keywords: potato, integrated nutrient management, acidic soils, nutrient uptake, vermicompost, rock phosphate, phosphate-solubilizing bacteria, late blight, Mozambique, tuber bulking, Sustainable, intensification

The research team evaluated six different fertilizer applications on Buxus sempervirens, the common boxwood: nitrogen, potassium, vermicompost, beneficial bacteria, mycorrhizal fungi, and sheep wool, an organic amendment that has attracted attention as a slow-release nutrient source. The goal was twofold. First, the researchers wanted to quantify how each treatment affected plant height, width, shoot development, leaf dimensions, root architecture, nutrient concentrations, and chlorophyll content. Second, they wanted to test whether machine learning algorithms could distinguish which fertilizer a plant had received simply by reading its aboveground morphology — a question with real implications for how growers might monitor plant nutrition in the future.

The results were strikingly clear for one treatment. Nitrogen emerged as the most effective fertilizer across nearly every measure of plant performance. Plants receiving nitrogen grew 25 percent taller and 34 percent wider than untreated controls, produced shoots 29 percent longer, and developed leaves 18 percent longer. The number of shoots per plant was also numerically higher under nitrogen, rising by 51 percent, although the overall treatment effect on shoot number did not reach statistical significance. Potassium ranked as the second most effective treatment, matching nitrogen’s 25 percent gain in plant height and delivering a 33 percent increase in plant width, along with a 9 percent improvement in shoot length.

Perhaps the most dramatic effects appeared below ground. Root architecture — the hidden half of plant performance that growers rarely see — responded strongly to nitrogen. Root length increased by 45 percent, root surface area by 81 percent, and root volume by a remarkable 119 percent compared with control plants. The number of root forks, the branching points where roots split and explore the soil, was numerically 38 percent higher under nitrogen, though again the overall treatment effect was not statistically significant. These findings matter because a well-developed root system determines how efficiently a plant captures water and nutrients, and how successfully it establishes after transplanting — a critical factor for a species routinely moved from nursery pots into landscape settings.

Nutrient analysis revealed a more nuanced picture. In roots, treatment effects were significant only for nitrogen and potassium concentrations, suggesting that the other measured elements were buffered against change regardless of what was applied. In leaves, the story was different: magnesium, phosphorus, potassium, iron, and manganese all responded significantly to the fertilizer treatments, while calcium, zinc, nitrogen, and copper showed no significant overall effects. Notably, sheep wool — the organic amendment in the trial — showed its strongest influence on selected nutrient responses, particularly potassium, iron, and manganese, hinting that this unconventional material may have a role in fine-tuning micronutrient nutrition even when its growth effects are modest.

Chlorophyll content, a proxy for the photosynthetic machinery that drives growth, varied according to leaf age and the timing of measurement. Nitrogen produced the highest mean chlorophyll values among young leaves measured in June, and nitrogen and potassium treatments generated the highest chlorophyll responses across measurement periods overall. However, the authors report that the overall treatment effect on chlorophyll was not statistically significant, a reminder that what looks like a clear pattern in a single measurement window may not hold across the full season.

The machine learning component of the study added a genuinely novel dimension. The researchers evaluated five classifiers — including J48, a decision-tree algorithm; Naïve Bayes; and Random Forest — using six aboveground morphological characteristics as input features. J48 delivered the highest performance on a hold-out test set, while Naïve Bayes achieved the best five-fold cross-validation accuracy. To understand which traits drove the models’ decisions, the team applied Random Forest feature-importance analysis and SHAP analysis, a technique that attributes each prediction to individual features. Both approaches converged on the same conclusion: plant size and shoot-development characteristics contributed more strongly to the models’ output than leaf dimensions did. In other words, when an algorithm tried to guess which fertilizer a boxwood had received, it relied chiefly on how big the plant was and how vigorously it had shot, not on the fine details of its leaves.

Yet the machine learning results came with an important caveat. While the classifiers identified treatment-related morphological patterns within the dataset, they showed limited generalization to previously unseen observations. This is a common and honest limitation in agricultural machine learning: models can memorize the structure of the data they were trained on without learning relationships robust enough to transfer to new plants, new seasons, or new growing conditions. The authors are candid about this, framing the machine learning analysis as a complementary tool rather than a replacement for conventional measurement — a way to surface which traits matter most, rather than a standalone diagnostic.

That framing points to the study’s broader significance. Fertilizer effects in boxwood proved to be strongly trait-specific: a treatment that excelled at driving height growth might have little effect on chlorophyll, and an amendment that barely moved growth metrics could still shift nutrient concentrations in meaningful ways. By combining conventional plant and nutrient analyses with interpretable machine learning, the researchers demonstrated a workflow that captures this complexity more completely than either approach alone. For nursery producers, the practical takeaway is straightforward — nitrogen remains the workhorse fertilizer for pushing boxwood growth, with potassium close behind, while organic options like sheep wool may earn their place through nutrient-specific effects rather than raw growth gains.

For the wider field of ornamental plant science, the study offers a template. As machine learning tools become more accessible, the challenge is no longer building models but building honest ones — models whose limitations are measured, whose feature importance is interpretable, and whose predictions are tested against data they have never seen. This boxwood trial, modest in scale but rigorous in design, shows what that discipline looks like in practice, and suggests that the future of fertilizer evaluation may belong to teams willing to pair a measuring tape and a root scanner with an algorithm willing to admit what it does not yet know.

Subject of Research: Effects of chemical and biofertilizer treatments on growth, root architecture, and nutrient dynamics of Buxus sempervirens, analyzed with machine learning

Article Title: Growth, nutrient dynamics, and root architecture responses of Buxus sempervirens to chemical and biofertilizer applications: an integrated experimental and machine learning approach

Article References: Sarı, Ö., Enginsu, E., & Çelikel, F. G. (2026). Growth, nutrient dynamics, and root architecture responses of Buxus sempervirens to chemical and biofertilizer applications: an integrated experimental and machine learning approach. BMC Plant Biology. https://doi.org/10.1186/s12870-026-09942-4

Image Credits: AI Generated

DOI: 10.1186/s12870-026-09942-4

Keywords: Buxus sempervirens, boxwood, nitrogen fertilizer, potassium, vermicompost, mycorrhiza, sheep wool, root architecture, machine learning, plant nutrition, ornamental horticulture, chlorophyll

The stakes could hardly be higher. More than 500 million smallholder farm families worldwide cultivate less than two hectares each, representing roughly 88 percent of all operational land holdings. In India, generations of inheritance have fragmented ancestral land so severely that average holding sizes collapsed from 2.28 hectares in 1970-71 to just 0.74 hectares by 2021-22. In Northeast India, the situation is even more acute: 78.9 percent of smallholders farm micro-plots plagued by resource constraints and seasonal water shortages. For these farmers, single-enterprise agriculture is no longer viable, and the researchers argue that the only way forward is upward, a strategy they call vertical expansion, in which nutrients and inputs are recycled among multiple enterprises stacked on the same tiny parcel of land.

The study site in Liarkhla village, perched at 950 to 1,010 meters above sea level, captures the essence of Eastern Himalayan fragility. The region receives a drenching 2,500 to 3,000 millimeters of rain annually, yet more than 90 percent of it falls between June and September, leaving the October-to-April months chronically water-stressed. The soils are acidic, with a pH of just 4.8, low phosphorus, and modest organic carbon. Farmers here rely on agriculture for survival in one of the world’s most climate-vulnerable hotspots, making the location an ideal real-world laboratory for testing whether integrated systems can actually buffer smallholders against climate shocks rather than merely sounding promising on paper.

Three models were evaluated, each on 0.5 hectares and replicated across 20 farmers’ fields. The PoultryFVV system combined 55 Vanaraja birds, 800 Indian Major Carp fingerlings in a 0.1-hectare pond, 0.35 hectares of vegetables including broccoli, cabbage, tomato, potato, and French bean, and a vermicompost unit. The DuckFVV model swapped poultry for 35 Khaki Campbell ducks, while the PigFVV model used 3 Lumsniang pigs. Each was benchmarked against traditional single-enterprise fish farming. The logic of integration is elegantly simple: livestock droppings fertilize pond water to feed fish, pond water irrigates vegetables, and farm waste is converted by earthworms into vermicompost that returns nutrients to the soil, closing the loop and slashing dependence on costly external inputs.

Carbon accounting followed IPCC greenhouse gas protocols and life cycle assessment, with methane and nitrous oxide converted to carbon dioxide equivalents using global warming potentials of 28 and 298 respectively. The results revealed a nuanced environmental picture. The PoultryFVV system recorded the highest methane emissions under high-emission scenarios at 1,536.8 kilograms of CO2-equivalent, and the largest overall carbon footprint at 1,674.2 kilograms of CO2-equivalent per year. The DuckFVV model proved the greenest, with the lowest footprint at 1,473.0 kilograms. Notably, the fishery component emerged as a major emissions hotspot, with feed production alone contributing 1,800 kilograms of CO2-equivalent annually, while pond methane added another 512.4 kilograms. Vermicomposting, however, cut methane emissions from handled manure by roughly half, confirming its value as a genuinely climate-smart practice.

The resilience data may be the study’s most striking finding. When rainfall deficits of 16 to 18.7 percent struck in 2021 and 2023, classified as stress years against the 30-year normal of 1,563 millimeters, all three integrated systems held their productivity remarkably steady. Yields dipped only marginally, from 6.00 to 5.56 tonnes per unit in the poultry model, yielding climate resilience indices of 92 to 93 percent across the board. Using the Climate Resilience Adaptation Index, which weighs adaptive capacity against exposure and sensitivity, the PoultryFVV system scored highest, with an adaptive capacity of 0.633 and an overall CRAI above 0.67, placing it firmly in the high-resilience category. The duck and pig models fell into medium and low-to-medium resilience bands respectively.

Economically, the contrast with conventional farming was stark. The PoultryFVV system generated a gross return of US$2,952.77 and a net return of US$1,757.59 per year, with a benefit-cost ratio of 2.47, while also creating 227 man-days of employment annually, the highest of any model. Traditional fish monoculture, by comparison, netted a dismal US$65.12. The pig-based system, though less profitable overall, achieved the highest daily economic efficiency at US$4.82 per day, thanks to the high market value of pig biomass. Breed selection mattered too: on-farm testing showed Khaki Campbell ducks laying 260 eggs per year with a feed conversion ratio of 2.5, dramatically outperforming indigenous ducks that produced just 120 eggs on a ratio of 4.0.

Sustainability metrics reinforced the poultry model’s dominance. It achieved the highest Sustainable Value Index at 0.561, while pond water quality remained within optimal aquaculture ranges across all systems, with pH between 7.30 and 7.50 and dissolved oxygen safely above 5.0 milligrams per liter. Beyond the experimental plots, the initiative catalyzed 47 new agri-enterprises across 17 villages, with a 67 percent adoption success rate in poultry-based systems, evidence that the model works not just under research supervision but in the messy economics of real farm households.

What makes this study significant is its empirical rigor in a domain often dominated by theoretical advocacy. By quantifying carbon footprints under both low and high methane conversion scenarios, measuring yield stability through actual drought years, and tracking financial returns across four full production cycles, the researchers have produced one of the most complete validations of integrated farming for mountain agriculture to date. The trade-offs are honestly reported: the most profitable model is not the lowest-emitting one, and carbon sequestration of just 2.28 kilograms of CO2-equivalent per year is negligible against emissions measured in the hundreds. Integration alone does not make a farm carbon-neutral, but it does make it dramatically more survivable.

For the millions of smallholders clinging to fragmented hill plots across South Asia and beyond, the message is one of pragmatic hope. Climate-smart integrated farming systems, the authors conclude, offer a scalable, decentralized pathway to move vulnerable farmers from high-risk monoculture toward resilient, entrepreneurial agrifood systems. The half-hectare poultry-fish-vegetable-vermicompost model, validated across four years of capricious Himalayan weather, now stands as a tested blueprint for turning the smallest farms in the world’s most fragile mountains into engines of both adaptation and income.

Subject of Research: Climate-smart integrated farming systems for tribal smallholders in the Eastern Himalayas, India

Article Title: Sustaining hill agriculture: climate-smart integrated farming systems for tribal smallholders in Eastern Himalayas, India

Article References: Baruah, M. S., Islam, M., Pathak, P. K., & Mohanty, A. K. (2026). Sustaining hill agriculture: climate-smart integrated farming systems for tribal smallholders in Eastern Himalayas, India. Frontiers in Agronomy, 8, Article 1946224. https://doi.org/10.3389/fagro.2026.1946224

Image Credits: AI Generated

DOI: 10.3389/fagro.2026.1946224

Keywords: integrated farming systems, climate-smart agriculture, Eastern Himalayas, smallholder farmers, carbon footprint, climate resilience, aquaculture, vermicompost, Meghalaya, tribal agriculture, livelihood security, greenhouse gas emissions

The study set out to answer a deceptively simple question. Both vermicompost and Piriformospora indica, a root-colonizing endophytic fungus sometimes classified in the genus Serendipita, are known individually to promote plant growth and reshape soil microbial populations. What remained largely unknown was what happens when the two are applied together, and whether their combined effect on apple seedlings is simply additive or something more synergistic. To find out, the researchers grew apple seedlings under four regimes: an untreated control, vermicompost alone, fungal inoculation alone, and the two combined. They then measured everything from seedling biomass and root architecture to photosynthetic capacity, soil chemistry, enzyme activity, and the composition of the rhizosphere microbiome—the teeming microbial ecosystem hugging the root surface.

The results were striking in their consistency. Every treatment that included either vermicompost or the fungus promoted seedling growth, encouraged root development, and enhanced photosynthetic capacity compared with untreated controls. But the combination outperformed both single treatments, delivering the strongest gains across nearly every metric the team tracked. Seedlings receiving both the fungus and the worm castings grew larger, built more extensive root systems, and photosynthesized more efficiently than their counterparts in any other group. For orchardists and nursery operators, the implication is that these two inputs, often marketed and applied separately, may work best as a paired prescription.

Nutrient uptake told a more nuanced story. The combined treatment significantly increased both the uptake fluxes—the rate at which phosphorus and potassium streamed into the roots—and the total contents of those two essential macronutrients in plant tissue. Vermicompost alone, by contrast, was the standout for nitrogen uptake, improving the seedlings’ acquisition of that nutrient without the fungus needing to be present. This divergence suggests that the two amendments operate through partially distinct physiological channels: the fungus appears to amplify phosphorus and potassium mobilization, while the organic matter in vermicompost feeds the nitrogen cycle directly. Growers tailoring fertilization strategies to specific nutrient deficiencies could, in principle, select one or both inputs accordingly.

Soil health metrics followed a similar pattern. Both vermicompost and the combined treatment improved soil fertility and boosted the activity of soil enzymes, the biological catalysts that drive decomposition, nutrient mineralization, and organic matter turnover. Notably, the fungus on its own showed no significant benefit to these soil properties. That asymmetry is scientifically telling: it implies that Piriformospora indica does not so much improve the soil directly as it reprograms the plant and its microbial entourage to exploit the soil more effectively. The vermicompost, meanwhile, supplies the raw biochemical substrate—the carbon, nitrogen, and micronutrients—that enzymes and microbes need to do their work. Together, the two create a feedback loop in which better soil feeds better roots, and better roots cultivate better soil.

The heart of the study, however, lies in its microbiome analysis. Using high-throughput sequencing of rhizosphere soil, the researchers found that all three treatments enriched taxa classified as plant-growth-promoting, or PGP, microbes—organisms known to fix nitrogen, solubilize minerals, produce plant hormones, or suppress pathogens. But which of these enriched taxa actually mattered for the growth response? To move beyond correlation, the team deployed random-forest analysis, a machine-learning method that ranks microbial features by their predictive power for a given outcome. The algorithm’s verdict was unambiguous: the bacterial phylum Actinobacteriota, and within it especially the genus Streptomyces, emerged as the key contributor distinguishing high-performing seedlings from the rest.

Streptomyces are the workhorses of the actinomycete world, famous both for their earthy smell in freshly turned soil and for their prodigious output of antibiotics, including the compounds behind many clinical drugs. In the rhizosphere, they are prized for their ability to solubilize phosphorus, produce indole-3-acetic acid and other auxin-type hormones that stimulate root growth, and outcompete pathogens. The Shanxi team did not stop at statistical association. In a crucial experimental step, they isolated four Streptomyces strains directly from fresh vermicompost and inoculated apple seedlings with them. The purified bacteria reproduced the growth-promoting effects observed with the full vermicompost treatment, enhancing seedling vigor and soil fertility on their own. That causal demonstration elevates the finding from an intriguing correlation to a functional mechanism: actinomycetes recruited or enriched by vermicompost and the fungus are not passive bystanders but active agents of plant growth.

The study’s design reflects a broader shift in plant science toward viewing crops as holobionts—plants plus their associated microbiomes—as integrated biological units. Earlier work cited by the authors has shown that vermicompost can suppress apple replant disease, that Piriformospora indica reshapes rhizosphere communities in willows and other species, and that specific bacterial strains such as Pseudomonas sp. CM11 can induce lateral root formation in apple rootstocks. What this new research adds is a mechanistic bridge: a specific bacterial taxon, identifiable by machine-learning analysis and verifiable through strain isolation, that links a widely used organic amendment and a model endophytic fungus to concrete physiological outcomes in a major fruit crop. The four Streptomyces strains have been deposited in GenBank, and the full microbiome dataset is available in the NCBI Sequence Read Archive, giving other researchers the raw material to build on the work.

The practical implications extend well beyond the apple orchard. Vermicompost is already a cornerstone of organic and low-input agriculture worldwide, valued for improving soil structure, water retention, and nutrient availability. Piriformospora indica, meanwhile, is increasingly marketed as a biostimulant for horticultural crops, prized for its broad host range and its capacity to confer tolerance to drought, salinity, and heavy metals. If the growth benefits of both depend substantially on recruiting actinomycetes, then management practices that favor these bacteria—such as maintaining organic matter inputs, minimizing disruptive tillage, and avoiding broad-spectrum biocides—could amplify the returns on either investment. Conversely, the finding that the fungus alone did not improve soil fertility cautions against expecting microbial inoculants to substitute for organic amendments; the two appear to be complements, not substitutes.

There are, of course, caveats. The experiments were conducted on apple seedlings under controlled conditions, and translating seedling responses to mature orchard trees across seasons and variable field soils remains a challenge that the authors themselves acknowledge in framing their conclusions. The random-forest approach identifies predictive taxa but cannot fully disentangle whether Streptomyces abundance is a cause or a consequence of vigorous growth, though the strain-inoculation experiment goes a long way toward resolving that ambiguity. Still, the convergence of evidence—community profiling, machine-learning attribution, and functional validation with isolated strains—makes a compelling case that actinomycetes are central players in vermicompost- and fungus-mediated plant growth. For a discipline often accused of cataloging microbes without explaining them, the study offers a template: find the keystone taxon, isolate it, and prove it works. In the rhizosphere of a young apple tree, at least, the earthworm’s gift and the fungus’s partnership appear to converge on the same microscopic allies, quietly manufacturing the growth that growers see above ground.

Subject of Research: The role of rhizosphere Actinomycetes in vermicompost- and Piriformospora indica-mediated apple seedling growth and nutrient uptake

Article Title: Rhizosphere microbiome analysis revealed the role of Actinomycetes in vermicompost- and Piriformospora indica-mediated apple growth

Article References: Zhao, Q., Li, Q., Ma, X., Li, H., Qin, M., Zhang, Y., Chen, M., Cheng, C., & Li, L. (2026). Rhizosphere microbiome analysis revealed the role of Actinomycetes in vermicompost- and Piriformospora indica-mediated apple growth. Plant and Soil. https://doi.org/10.1007/s11104-026-09099-x

Image Credits: AI Generated

DOI: 10.1007/s11104-026-09099-x

Keywords: apple, vermicompost, Piriformospora indica, rhizosphere microbiome, Actinomycetes, Streptomyces, plant growth promotion, soil fertility, nutrient uptake, soil enzymes, endophytic fungus, random forest analysis

The experiment took place at Palampur in Kangra district, at an elevation of roughly 1,290 metres, on a silty clay loam Alfisol classified as Typic Hapludalf. The starting soil was acidic, with a pH of 5.63, moderate organic carbon of 7.89 grams per kilogram, and available nitrogen, phosphorus and potassium of 255.2, 17.5 and 188.6 kilograms per hectare respectively. Rainfall during the June-to-October 2022 maize season totalled an abundant 1,847.4 millimetres, and the crop was grown entirely rainfed with no supplemental irrigation. The researchers sowed the maize variety Kanchan at 20 kilograms of seed per hectare and applied the recommended fertilizer dose of 120:60:40 kilograms of nitrogen, phosphorus pentoxide and potassium oxide per hectare through urea, single superphosphate and muriate of potash, splitting the nitrogen between a basal application and two top-dressings at knee-high and pre-tasselling stages.

What made the trial distinctive was its nine-treatment structure, arranged in a randomized block design with three replications, which pitted full, moderate and reduced mineral fertilizer levels against combinations of farmyard manure, vermicompost and a mixed inoculant of Azotobacter and Bacillus species. The organic amendments differed meaningfully in composition: vermicompost carried 1.27 percent nitrogen on a dry-matter basis against 0.89 percent in farmyard manure, along with somewhat higher phosphorus. The bioinoculants, obtained from the university’s Department of Organic Agriculture and Natural Farming, were mixed into the organic amendment before field application, a practical delivery method that farmers could replicate. The central question was how much mineral fertilizer could be trimmed while still sustaining yield, nutrient uptake, soil fertility and economic returns in a system where cation exchange capacity, microbial biomass and enzyme activity jointly govern fertilizer efficiency.

The answer, at least under these conditions, was 25 percent. The treatment combining 75 percent of the recommended NPK with 5 tonnes of vermicompost per hectare and the Azotobacter-Bacillus consortium produced the highest observed grain yield of 40.8 quintals per hectare and stover yield of 62.5 quintals per hectare. Compared with the conventional full-fertilizer control, that represents a 34.4 percent increase in grain yield, a figure that will catch the attention of any agronomist who has watched yield stagnate under fertilizer-only regimes. Total nutrient uptake told the same story: the leading treatment accumulated 121.0 kilograms of nitrogen, 31.3 kilograms of phosphorus and 92.2 kilograms of potassium per hectare, increases of 36.6, 78.9 and 53.4 percent respectively over sole mineral fertilization. Grain protein and ash content also peaked under the integrated packages, reflecting the tighter coupling between nutrient supply and grain filling.

Importantly, the researchers were careful about their statistics. The vermicompost-based treatment did not differ significantly from its farmyard manure counterpart at 75 percent NPK for most measured responses; the two formed a single leading statistical group across yield components, nutrient uptake and most soil indicators. Available soil potassium was the only variable that separated them significantly, favouring the vermicompost package. This nuance matters because it means farmers with ready access to either amendment have viable options, with the choice potentially driven by local availability and price rather than by a fixed agronomic hierarchy. The study also showed that the integration cannot be reduced to a single ingredient: the responses reflect the combined effect of fertilizer level, amendment type and inoculation within each package, and the trial design did not isolate the bioinoculant effect factorially.

The soil story may prove even more consequential than the yield numbers. Post-harvest measurements revealed that the integrated treatments lowered bulk density, improved water-holding capacity, and raised soil organic carbon to 8.48 grams per kilogram under the leading treatment. Microbial biomass carbon reached 112 milligrams per kilogram and dehydrogenase activity 4.4 micrograms of triphenyl formazan per gram per hour, gains of 32.9 and 51.7 percent respectively over the full-fertilizer control. Dehydrogenase activity is a particularly telling metric because it quantifies the oxidative metabolism of living microbial communities rather than a static chemical pool, so its sharp rise signals a genuine reactivation of the soil’s biological machinery. DTPA-extractable iron, manganese, zinc and copper also peaked under the integrated treatments, linking micronutrient availability to the broader fertility response.

To understand whether these individual improvements were connected, the team turned to principal component analysis of the post-harvest soil indicators. Two components explained 93.40 percent of the total variance, with the first alone accounting for 85.45 percent. That dominant axis aligned water-holding capacity, organic carbon, available nitrogen and phosphorus, micronutrients and microbial biomass carbon, while bulk density loaded in the opposite direction. The correlation matrix confirmed strong positive associations among organic carbon, available nutrients, micronutrients and the biological indicators, and consistent negative associations between bulk density and nearly every fertility measure. Soil pH, by contrast, barely moved, remaining in a narrow and statistically non-significant range of 5.6 to 5.7 across treatments. The authors interpret this covariance structure as evidence that the response to integrated nutrient management was functionally integrated across physical, chemical and biological domains, driven by enhanced nutrient buffering and biologically mediated nutrient cycling rather than by nutrient addition alone.

Economics added a final, pragmatic dimension. The vermicompost-based package generated gross returns of 99,340 rupees per hectare, equivalent to about 1,264 US dollars, net returns of 59,722 rupees per hectare, and an economic efficiency of 567.66 rupees per hectare per day, the highest of any treatment. Yet the conventional full-fertilizer control retained the best benefit-cost ratio and return per rupee invested simply because its input costs were lower. This distinction is crucial for policy: the integrated package delivered the strongest productivity and soil outcomes, but only when yield gains were large enough to offset the additional expense of amendments and inoculants. At 50 percent NPK, that equation failed. The heavily reduced treatments improved several soil and biological indicators relative to the control but could not sustain comparable nutrient acquisition or profitability, demonstrating that organic and microbial inputs require an adequate mineral backbone to function.

The study’s conclusions are deliberately bounded. The findings come from a single season at a single site in an acidic Himalayan Alfisol, and the authors state plainly that wider recommendation requires multi-season and multi-location validation of nutrient-recovery efficiency, residual fertility, inoculant persistence, carbon stabilization and direct greenhouse-gas emissions, which were not measured here. Even so, the message is a significant one for a world grappling with fertilizer price volatility and widespread soil degradation. Fertilizer reduction, the authors argue, should not be approached as a simple decrease in mineral input but as a redesign of nutrient supply through mineral, organic and biological integration. Where vermicompost is available, pairing 75 percent of the standard NPK dose with the Azotobacter-Bacillus consortium offers a practical, economically defensible template for growing more maize while rebuilding the soil that makes future harvests possible.

Subject of Research: Integrated nutrient management combining vermicompost, Azotobacter-Bacillus inoculation and reduced mineral NPK for sustainable maize production

Article Title: Vermicompost-assisted Azotobacter and Bacillus inoculation enables partial substitution of mineral NPK and improves maize yield, nutrient uptake, soil fertility, and biological activity

Article References: Bahman, M., Singh, D., Venkateswarlu, M., Sankhyan, N. K., Thakur, P., & Kumari, S. (2026). Vermicompost-assisted Azotobacter and Bacillus inoculation enables partial substitution of mineral NPK and improves maize yield, nutrient uptake, soil fertility, and biological activity. Discover Soil, 3(1), Article 176. https://doi.org/10.1007/s44378-026-00336-4

Image Credits: AI Generated

DOI: 10.1007/s44378-026-00336-4

Keywords: maize, integrated nutrient management, vermicompost, Azotobacter, Bacillus, NPK fertilizer, soil fertility, microbial biomass carbon, dehydrogenase activity, nutrient uptake, Alfisol, sustainable agriculture

The work builds on an earlier innovation from the same laboratory: a vermicompost made from finely ground bamboo and kudzu, a nitrogen-fixing but notoriously invasive vine. That original blend, known as VFBK, had already demonstrated an impressive capacity to suppress soilborne pathogens and plant-parasitic nematodes. Yet its path to commercial use was blocked by two stubborn problems. Grinding bamboo down to fine particles between 0.2 and 1.0 millimeters proved expensive, and harvesting enough wild kudzu added further labor costs. Worse, the finished compost carried relatively little nitrogen, and seedlings grown in it often developed visibly pale leaves—a sign that the plants were starved for this essential nutrient.

To overcome these limitations, the researchers reengineered the entire production system. They replaced kudzu with rapeseed oilcake, a widely available by-product of oil pressing that carries a much higher and more stable nitrogen content, with a carbon-to-nitrogen ratio of roughly 8 compared with about 16 for kudzu. More importantly, they abandoned fine grinding altogether, using bamboo particles between 0.3 and 6.5 millimeters with a mean of 1.6 millimeters—roughly two and a half times coarser than before. The resulting product, dubbed VCBR, was compared against both the original kudzu-based VFBK and a finely ground bamboo–rapeseed oilcake blend called VFBR, allowing the team to separate the effects of particle size from those of the nitrogen source.

The production process itself followed classic vermicomposting principles. Bamboo culms were ground, soaked in water for at least 24 hours to remove compounds repellent to earthworms, and mixed with either kudzu or rapeseed oilcake in plastic containers. After four weeks of precomposting at 25 degrees Celsius, roughly 70 grams of red wiggler earthworms (Eisenia fetida) were added to each container. Over three months, with moisture maintained at 70 to 80 percent, the worms and their associated microbes transformed the fibrous bamboo into a dark, biologically active amendment. Three replicate containers were prepared for each recipe, and equal amounts from each were pooled into composite samples for analysis.

The cost savings were dramatic. Estimated at a practical production scale of one metric ton per month, VCBR came in at 267,200 yen—about 1,670 US dollars—per ton. Simply switching back to finely ground bamboo added 32,960 yen, roughly 206 dollars, per ton. The original kudzu-based VFBK was the most expensive of all, at 349,600 yen, or about 2,185 dollars per ton, burdened by both fine grinding and the labor of harvesting and processing kudzu. For small- to medium-scale producers hoping to use locally available bamboo biomass, the coarser recipe removes a major economic barrier to adopting organic disease-suppressive amendments.

Chemical analysis revealed that particle size had surprisingly little effect on the raw bamboo itself: coarsely and finely ground material showed no significant differences in water-soluble nutrients or pH. The real differences emerged after vermicomposting. Both rapeseed-based blends outperformed the kudzu version on nitrogen: VFBK had much lower ammonium content and a markedly higher carbon-to-nitrogen ratio, confirming that swapping kudzu for oilcake improved nitrogen availability. Interestingly, although identical amounts of rapeseed oilcake were added to VCBR and VFBR, the finely ground version ended up with higher total nitrogen. The authors suggest that the coarser particles may have improved aeration during composting—larger particles create more free air space and better oxygen flow—and such conditions are known to influence nitrogen losses, though aeration was not directly measured.

The disease-suppression trials formed the heart of the study. The team tested two economically important pathosystems: shiso, a popular Japanese culinary herb, challenged with Pythium myriotylum under warm conditions, and cucumber challenged with Globisporangium ultimum at moderate temperatures. Each vermicompost was mixed into commercial nursery soil at 20 percent by volume, with unamended soil serving as the control. Disease was triggered by pouring inoculum grown on bentgrass-seed agar around the base of seedlings, and incidence was scored four days later across multiple independent experimental runs. Because statistical analysis revealed significant treatment-by-run interactions, the researchers compared each treatment against the control within every individual run using Dunnett’s test.

The results were striking. VCBR proved the most consistent performer of the three, significantly reducing damping-off in all three runs of the shiso–Pythium assay and in three of four runs of the cucumber–Globisporangium assay. VFBR suppressed disease in two runs of each assay, while the original VFBK managed only two runs against Pythium and a single run against Globisporangium. Notably, these differences could not be explained by the general microbial indicators the team measured—culturable fungal and bacterial counts, fungal-to-bacterial ratios, and total adenylate levels via bioluminescence assay all came back statistically indistinguishable among treatments. The authors point out that disease suppressiveness in organic amendments is generally tied to biological properties such as microbial community composition and specific antagonistic organisms, which their plate-count methods could not capture, leaving the precise mechanism an open question for future work.

There was, however, a significant catch. Seedlings grown in VCBR-amended media showed reduced SPAD values—a chlorophyll meter reading that serves as a proxy for leaf greenness and nitrogen status—in both shiso and cucumber compared with plants in unamended commercial soil. The finely ground VFBR was gentler: it lowered SPAD in shiso but not significantly in cucumber. This pattern suggests a genuine trade-off between production cost and seedling chlorophyll status, likely rooted in nitrogen dynamics. The authors emphasize that extractable ammonium and total carbon-to-nitrogen ratios do not fully predict nitrogen availability to seedlings; the balance between mineralization and immobilization after the compost enters the nursery substrate, along with the physical and microbial properties of the medium, all play a role. Encouragingly, they note that nitrogen status could potentially be improved simply by adjusting the amount of rapeseed oilcake added during production, since the oilcake carries more total nitrogen than kudzu—a hypothesis that now awaits experimental testing.

Beyond the greenhouse, the study carries a broader environmental message. Unmanaged moso bamboo forests now cover approximately 167,000 hectares of Japan, expanding relentlessly into farmland and native forests, reducing understory diversity, destabilizing soils, and worsening wildlife damage. Converting this troublesome biomass into a disease-suppressive nursery medium offers a rare win-win: a use for an invasive resource and a step toward pesticide-free seedling production. The authors caution that their cost estimates rest on specific assumptions and that the mechanisms underlying suppression remain unelucidated, but the direction is clear. With its combination of simple processing, accessible feedstocks, and consistent protection against two major seedling pathogens, the coarse bamboo–rapeseed oilcake vermicompost stands as a promising foundation—provided its nitrogen supply can be tuned to keep seedlings as green as they are healthy.

Subject of Research: Development of a low-cost, disease-suppressive bamboo-based vermicompost for seedling production

Article Title: Coarsely ground bamboo and rapeseed oilcake produce a lower-cost vermicompost with damping-off suppressiveness

Article References: Kawasumi, R., & Tojo, M. (2026). Coarsely ground bamboo and rapeseed oilcake produce a lower-cost vermicompost with damping-off suppressiveness. Discover Soil, 3(1), Article 172. https://doi.org/10.1007/s44378-026-00335-5

Image Credits: AI Generated

DOI: 10.1007/s44378-026-00335-5

Keywords: vermicompost, bamboo, rapeseed oilcake, damping-off, Pythium myriotylum, Globisporangium ultimum, Eisenia fetida, nursery medium, soilborne disease, organic amendment, invasive species, sustainable agriculture

The research, conducted during the kharif growing seasons of 2019 and 2020 at the Crop Research Centre of Sardar Vallabhbhai Patel University of Agriculture and Technology in Meerut, Uttar Pradesh, set out to test a deceptively straightforward hypothesis: that the timing of organic nutrient application is a decisive factor in how well nutrients released from those materials match the changing appetite of a growing rice crop. The experimental soil was a sandy loam with a neutral reaction, low in organic carbon and available nitrogen, and only moderate in phosphorus and potassium, precisely the kind of tired, intensively farmed ground where integrated nutrient management is supposed to earn its keep. Fourteen treatments were laid out in a randomized block design with three replications, all growing the popular aromatic variety Pusa Basmati-1509, transplanted on July 16 in both seasons.

The treatment structure was carefully engineered to isolate the effects of three variables: the source of organic nitrogen, the substitution rate, and the timing of incorporation. Dhaincha, a fast-growing leguminous green manure, and vermicompost, the nutrient-rich product of earthworm-digested organic waste, each replaced either 25 percent or 37.5 percent of the recommended nitrogen dose. Each combination was incorporated at one of three timings: ten days before planting, five days before planting, or on the planting date itself. The remaining nitrogen was supplied through conventional chemical fertilizers, with phosphorus and potassium applied at planting at standard rates of 60 kilograms of P2O5 and 40 kilograms of K2O per hectare, and nitrogen split between the basal dose and applications at tillering and panicle initiation. A fully unfertilized control and a treatment receiving only the recommended chemical fertilizers completed the design, giving the team clean benchmarks against which to judge every organic strategy.

The results traced a familiar but revealing arc. Available nitrogen in the soil declined as the crop advanced through its life cycle in every treatment, a pattern driven by continuous plant uptake. What differed was how much nitrogen remained available at each stage, and here the timing of organic incorporation mattered enormously. At planting, available nitrogen ranged from 218 to 242 kilograms per hectare, peaking in a treatment where dhaincha replaced 37.5 percent of nitrogen applied five days before planting. By maximum tillering, the highest value of 248 kilograms per hectare appeared where 25 percent of nitrogen came from dhaincha incorporated right at planting. At flowering, vermicompost applied at 37.5 percent substitution on the planting date took the lead, and after harvest the same vermicompost-based treatment held the maximum residual nitrogen of 211 kilograms per hectare. The unfertilized control sat at the bottom of the table at every single stage, a stark illustration of native soil nitrogen being mined without replacement.

The phosphorus and potassium data reinforced the same message from a different angle. Available phosphorus ranged from 14.8 to 16.45 kilograms per hectare at planting and reached its flowering-stage maximum of 16.80 kilograms per hectare and harvest maximum of 15.80 kilograms per hectare in the late-applied vermicompost treatment. Potassium told an even more dramatic story: after dipping to between 127.5 and 176 kilograms per hectare at flowering, residual available potassium climbed back after harvest, with the 37.5 percent vermicompost treatment recording the highest post-harvest value of 158 kilograms per hectare. Sulphur availability, measured in milligrams per kilogram of soil, showed a notable post-harvest buildup, peaking at 16.95 mg kg⁻¹ in the same vermicompost treatment. Available zinc, initially low at 0.78 to 0.91 mg kg⁻¹, rose through the season in organically amended plots, reaching 1.07 mg kg⁻¹ at tillering and up to 1.04 mg kg⁻¹ at flowering in the highest-substitution treatments. Only soil organic carbon refused to move significantly, a reminder that this slow-turning pool resists short-term manipulation.

The mechanisms behind these patterns are well understood in soil chemistry, and the Meerut results slot neatly into that framework. Green manures like dhaincha decompose rapidly, releasing a flush of nitrogen that, if timed correctly, coincides with the crop’s early demand. Vermicompost behaves differently: its nitrogen is released gradually, sustained by the microbial consortia and humic substances it carries, which improve soil structure, aeration, and moisture retention and thereby create a more favorable environment for nitrifying bacteria. That same biological activity explains the phosphorus gains, because decomposition releases organic acids that solubilize otherwise locked-up native phosphorus, while stimulated phosphatase enzymes mineralize organic phosphorus into plant-available forms. For potassium, organic acids and complexing agents released during decomposition interact with clay minerals, reducing fixation and freeing potassium that would otherwise remain unavailable. Zinc benefits from chelation, as soluble organo-zinc complexes shield the micronutrient from precipitation and antagonistic reactions in the soil.

The yield data delivered the study’s most commercially persuasive finding. When 25 percent of the recommended nitrogen was supplied through dhaincha incorporated at planting time, combined with chemical fertilizer for the remainder, biological yield, the combined grain and straw harvest, reached 108.24 quintals per hectare, statistically superior to most other treatments including several that used higher organic substitution rates or different timings. The unfertilized control, by contrast, produced only 58.24 quintals per hectare, less than half the output, a dramatic demonstration that even the best-managed soil cannot sustain intensive rice production on its native fertility alone. Notably, the winning strategy outperformed the full recommended chemical fertilizer treatment in the trials’ statistical comparisons of combined fertility and yield outcomes, and the study’s authors conclude that farmers can confidently substitute a quarter of their nitrogen requirement through dhaincha at planting or vermicompost applied ten days before sowing.

The broader implications reach well beyond one research farm. Vermicompost has previously been reported to cut input costs by 20 to 60 percent while improving cation exchange capacity and water retention, making it an accessible option for smallholders who often cannot afford full fertilizer recommendations. Green manuring offers an equally affordable pathway, restoring degraded land while boosting soil nitrogen at essentially the cost of a seed crop. The timing insight adds real value to both: applying organic material too early risks nitrogen losses through leaching, volatilization, denitrification, and immobilization before the crop can use it, while applying too late leaves the crop short during its hungriest early phases. Synchronizing incorporation with crop demand is thus not an agronomic nicety but a direct determinant of both yield and nutrient use efficiency, particularly in the sandy loam soils of the western Indo-Gangetic Plain where leaching losses can be severe.

There are honest caveats. The soil organic carbon differences among treatments never reached statistical significance over the two-year window, which the authors attribute to the inherent stability of the carbon pool and the short duration of the trial; the fact that the highest-substitution vermicompost treatment held the top organic carbon reading at three of four sampling stages hints at longer-term sequestration potential that only multi-year work can confirm. Seasonal and site specificity also limit how far the exact numbers can be generalized. Yet the central conclusion stands on unusually firm ground: combining modest rates of organic inputs with chemical fertilizers, at the right moment, builds a more resilient nitrogen economy in the soil, sustains the availability of phosphorus, potassium, sulphur, and zinc through the critical growth stages, and delivers a heavier harvest. For a nation that must find tens of millions of additional tons of rice by the end of the decade, a quarter of its nitrogen coming from earthworms and legumes may prove to be one of the cheapest climate-smart tools available.

Subject of Research: Temporal effects of dhaincha green manure and vermicompost application timing on nutrient bioavailability and yield in basmati rice

Article Title: Temporal assessment of nutrient bioavailability in rice using different organic inputs

Article References: Pathak, S. O., Luthra, N., Singh, O., Kumar, A., Das, N., Kumar, R., Sachan, S., Singh, J., & Naik, B. S. S. S. (2026). Temporal assessment of nutrient bioavailability in rice using different organic inputs. Discover Soil, 3(1), Article 142. https://doi.org/10.1007/s44378-026-00299-6

Image Credits: AI Generated

DOI: 10.1007/s44378-026-00299-6

Keywords: rice, basmati, soil fertility, vermicompost, green manure, dhaincha, integrated nutrient management, nitrogen, phosphorus, potassium, micronutrients, sustainable agriculture

The research team, led by Daggupati Sridhar of Siddarth Engineering & Technology and the Manipal Academy of Higher Education, together with Koppala Siva and Are Vigneshwari, chose a demanding setting for the investigation. The plant sits at Padubidri, about eight kilometres inland from the Arabian Sea, in a hydrogeologically sensitive zone of high monsoon rainfall, permeable soils and shallow aquifers. These conditions accelerate the movement of contaminants from the surface into the groundwater that local communities depend on. The plant, operational since 2012, disposes of coal combustion residues that leach metals under intense seasonal rain, making the region a natural laboratory for studying how industrial waste migrates through a coastal landscape.

To capture both the wettest and driest extremes of contaminant mobility, the team sampled groundwater and soil during the monsoon in October 2018 and again in the summer of March 2019. Four locations — Padibettu, two sites at Nagarjuna Gate, and the Main Gate — were selected within a ten-kilometre radial zone of the plant, distributed to the north, south and east. The western direction was deliberately excluded because coastal and harbour activities there could introduce contamination unrelated to the power plant and confound the results. Groundwater was drawn from open wells in active domestic use, avoiding stagnant sources, while soil was collected at two depths of two and four inches near each well to trace vertical movement of metals through the shallow profile.

The analytical workflow combined physical, chemical and biological methods. Soil texture was characterised through dry sieve analysis, moisture content measurements and Atterberg limit tests following ASTM standards, revealing predominantly well-graded silty clay soils of low to medium plasticity. These fine-grained soils matter because their large surface area and clay content govern how much water they hold and how strongly they adsorb trace metals, directly influencing whether contaminants stay put or travel downward. Trace metals — lead, copper, cadmium and nickel — were quantified using atomic absorption spectrophotometry after filtration of water samples and microwave-assisted acid digestion of soil in a mixture of nitric, hydrofluoric and hydrochloric acid at temperatures up to 260 degrees Celsius, ensuring complete recovery of metals from both silicate minerals and organic fractions.

The groundwater results were largely reassuring but carried one warning sign. Water pH ranged from 4.54 to 6.22, below the Bureau of Indian Standards acceptable range of 6.5 to 8.5 for drinking water, a acidity the authors attribute to rainwater interacting with acidic oxides in coal combustion residues. Total dissolved solids climbed in summer, with values at the two Nagarjuna Gate sites exceeding the acceptable limit of 500 milligrams per litre during the dry season, though all samples stayed well within the permissible limit of 2,000. Turbidity remained low throughout. Among the metals, copper stayed comfortably below its 0.05 milligram per litre limit, cadmium appeared only at trace levels, and nickel was mostly undetected. Lead, however, reached 0.0179 milligrams per litre and marginally exceeded the 0.01 milligram per litre acceptable limit at certain locations, particularly during the monsoon, pointing to localised contamination linked to fly ash leaching.

Lead’s exceedance is significant because of its health profile. The element is persistent and non-biodegradable, accumulates in biological tissues, and is associated with neurological, developmental and cardiovascular disorders, with children and pregnant women most vulnerable. The study also documents a clear soil-to-groundwater pathway: locations showing detectable lead and copper in soil leachates showed corresponding metal presence in the underlying wells, indicating vertical transfer through the vadose zone during seasonal recharge. Because residents rely heavily on shallow open wells and borewells for drinking and domestic use, the authors argue that continuous monitoring is essential, especially during and after the monsoon when infiltration and leaching are at their peak.

The second half of the study pivots from diagnosis to treatment. Fly ash, despite its metal content, also carries calcium, magnesium, iron and potassium, and its alkalinity can counteract acidic soils — a liming effect the experiments confirmed. The team amended contaminated agricultural soil with fly ash alone and in combination with vermicompost, then measured how metals behaved. Increasing fly ash proportions raised metal concentrations, confirming ash as a source of trace metals, but the combined fly ash–vermicompost treatments told a different story: copper and nickel concentrations dropped relative to fly ash-only treatments, lead became non-detectable in most combined mixes, and soil pH rose from an acidic 5.53 in untreated soil to between 7.02 and 8.30. The authors attribute this stabilisation to complexation of metals by humic and fulvic acids, adsorption onto organic functional groups, microbial immobilisation and improved soil aggregation.

Biological validation came from greenhouse pots of ragi (Eleusine coracana), a staple millet crop, sown with 25 seeds per pot across eight treatments and monitored over 21 days in weekly intervals. Fly ash alone produced moderate growth gains at lower doses, but root elongation was constrained at higher ash proportions, consistent with sub-lethal metal stress. The standout results came from the balanced blends: 5 percent fly ash with 15 percent vermicompost, and 2.5 percent fly ash with 17.5 percent vermicompost, delivered superior shoot elongation and root development compared with both untreated control soil and ash-only treatments. In contrast, the ash-heavy 15 percent fly ash with 5 percent vermicompost mix performed comparatively poorly, showing that too little organic matter leaves metals from the ash insufficiently stabilised.

The study’s broader significance lies in its integrated framing. Most previous work around thermal power plants has focused on characterising pollution and assessing risk, with little attention to remediation mechanisms validated by living plants. By linking physical soil behaviour, chemical speciation and biological response in a single framework, the researchers demonstrate a circular-economy pathway in which an industrial liability becomes an agricultural input — one that aligns with the United Nations Sustainable Development Goals on clean water, responsible consumption and life on land. The approach is inexpensive, uses materials already on site, and reduces dependence on synthetic fertilisers.

The authors are candid about the limitations. Sampling covered only four locations and two seasons, soil parameters derived from single measurements without replicates limited statistical treatment, and the pot experiments, while controlled, cannot fully reproduce field-scale behaviour over years. They call for expanded spatial and temporal monitoring, formal human health and ecological risk indices, advanced techniques such as ICP-MS and geospatial modelling, and long-term field trials of fly ash–compost amendments. For now, the message from the Udupi coast is measured but hopeful: contamination around the plant remains largely within regulatory limits, yet the persistence and bioaccumulative nature of heavy metals demand vigilance — and the waste that caused the problem may, in carefully balanced doses with compost, become part of the remedy.

Subject of Research: Heavy metal contamination of soil and groundwater near a coal-fired power plant and the use of fly ash–vermicompost amendments for soil remediation and plant growth

Article Title: Assessment of heavy metal contamination in soil and groundwater near a coal based thermal power plant and evaluation of fly ash and vermicompost as sustainable soil amendments for plant growth

Article References: Sridhar, D., Siva, K., & Vigneshwari, A. (2026). Assessment of heavy metal contamination in soil and groundwater near a coal based thermal power plant and evaluation of fly ash and vermicompost as sustainable soil amendments for plant growth. Discover Green Chemistry, 1(1), Article 14. https://doi.org/10.1007/s44509-026-00016-0

Image Credits: AI Generated

DOI: 10.1007/s44509-026-00016-0

Keywords: fly ash, heavy metals, groundwater contamination, thermal power plant, vermicompost, soil remediation, lead contamination, Udupi, soil pH, ragi, green chemistry, circular economy

The research team, led by Irshad Ahmad Bhat together with Khushboo Guleria, Anamika Kumari, Sajida Banoo, Zahoor A. Kaloo and Mudasir Fayaz, collected fresh rhizomes in May 2022 from wild populations at Gulmarg and Aharbal in Jammu and Kashmir, regions the study describes as part of a recognized biodiversity hotspot. Voucher specimens were verified and deposited in the herbarium of the Centre for Biodiversity and Taxonomy at the University of Kashmir. The broader context is sobering: the Kashmir Himalaya alone harbours roughly 1,123 medicinal plant species, and an estimated 15,000 medicinal plant species worldwide now face extinction risk as demand for plant-derived therapies outpaces natural supply.

The core of the vegetative propagation work involved slicing rhizomes lengthwise into segments, sterilizing them in a 2 percent Bavistin fungicide solution, and then soaking the pieces for 48 hours in different plant growth regulators before planting them in pots. The hormones tested included gibberellic acid (GA3), the synthetic auxin indole-3-butyric acid (IBA), the cytokinin benzylaminopurine (BAP) and the aromatic cytokinin meta-topolin, each at 50, 100, 150 and 200 parts per million, alongside untreated controls. The results were striking. Cuttings treated with 150 ppm GA3 sprouted at a rate of 83.34 percent, compared with just 25 percent in untreated controls, and sprouted fastest, in an average of only 20.75 days.

Gibberellin treatment did far more than speed germination. GA3 at 150 ppm produced plants with an average of 44.75 leaves per plant, a shoot length of 16.6 centimetres and a rhizome length of 9.5 centimetres, all significantly higher than the control group. The authors explain that gibberellins are known to accelerate the transport of cytokinins to developing buds and to modify carbohydrate metabolism, which helps explain the vigorous sprouting and organ development observed. Interestingly, meta-topolin failed entirely to stimulate rhizome sprouting, underscoring how species-specific hormone responses can be and why empirical optimization is essential before any conservation program scales up.

Because what a cutting grows in matters nearly as much as what it is dipped in, the team also tested thirteen different soil compositions mixing soil, sand, vermicompost, peat moss and pebbles. The winning combinations were a 1:1:1 blend of soil, sand and vermicompost and a 1:1:1 mix of soil, pebbles and vermicompost, both of which achieved a perfect 100 percent sprouting rate. The fastest sprouting occurred in the soil-pebble-vermicompost mix at 19.75 days. The authors attribute the success of these porous, organic-rich substrates to better aeration and drainage, conditions that mirror the rocky, well-drained alpine meadows where the species naturally grows, and note that vermicompost supplies slow-release nitrogen and phosphorus while boosting microbial activity in the rooting zone.

The second half of the study moved from the greenhouse to the sterile laboratory. Healthy nodal segments from polyhouse-grown donor plants were disinfected using six different chemical sterilization protocols, and the most effective protocol achieved a contamination rate of only 8.46 percent, minimal tissue necrosis of 2.84 percent and an explant survival rate of 93.14 percent. The study found that mercuric chloride worked best not alone but in combination with sodium hypochlorite, consistent with earlier findings in pomegranate, bitter gourd and gerbera. With clean cultures established, the explants were placed on Murashige and Skoog medium supplemented with varying concentrations of the cytokinins meta-topolin and thidiazuron (TDZ).

Cytokinin choice and dose proved decisive for shoot regeneration. Neither hormone induced any shoots at all in regulator-free control medium, indicating that endogenous hormone levels in the explant tissue are insufficient to trigger regeneration on their own. Responses rose in a concentration-dependent manner up to 3.5 milligrams per litre, where TDZ alone produced a 75 percent regeneration frequency with 5.33 shoots per explant, and meta-topolin alone achieved 72.25 percent with six shoots per explant. Pushing concentrations to 4 milligrams per litre actually reduced regeneration efficiency, a classic supra-optimal dose response. Even better results came from pairing cytokinins with auxins: the combination of 3.5 milligrams per litre TDZ with 1.25 milligrams per litre IBA delivered the study’s headline figure of 82 percent regeneration, six shoots per explant, shoots up to 6.41 centimetres long and the shortest induction period of just 19.33 days.

Perhaps the most technically interesting component involved inducing the plantlets to form micro-rhizomes in culture. Because the medicinal value of A. fragrans is concentrated in its rhizomes, wild harvesting is inherently destructive, so producing rhizomes in vitro offers a way to supply raw material without touching wild populations. When shoots were transferred to medium containing the auxin naphthalene acetic acid (NAA), rhizome formation followed a clear dose response, peaking at 1.5 milligrams per litre NAA with a 71.45 percent induction rate, rhizomes averaging 6.02 centimetres, and the shortest induction time of 35.73 days. No rhizomes formed in regulator-free medium or at the highest NAA dose, reinforcing the narrow window of effective concentration.

The final bottleneck, and often the graveyard of micropropagation protocols, is hardening, the transition of fragile laboratory plantlets to ordinary greenhouse life. Here the team washed agar from plantlets bearing well-developed micro-rhizomes, moved them first into vermiculite under high humidity, and then into pots of soil, sand and vermicompost. Three quarters of the plantlets survived, and, crucially, no visible phenotypic differences appeared between the laboratory-raised plants and their wild relatives. The authors candidly acknowledge one limitation: molecular markers such as ISSR or RAPD were not used to confirm clonal fidelity at the genetic level, so hidden somaclonal variation cannot be fully ruled out. The regenerated plants were eventually transferred to a prepared plot at the Kashmir University Botanical Garden in June.

Taken together, the protocols offer a dual pathway forward: fast, cheap field multiplication of elite clones via GA3-treated rhizome cuttings in vermicompost-enriched soil, and a high-throughput tissue culture system for producing disease-free, genetically uniform planting stock at industrial scale. Both routes circumvent the species’ bottleneck of slow, unreliable seed germination and directly reduce pressure on wild populations whose rhizomes are currently harvested destructively. The authors argue the framework is readily transferable to other endangered Himalayan medicinal plants and set out the next research frontier: scaling up root biomass in culture, applying elicitation strategies to boost secondary metabolite production, and building the phytochemical and pharmacological database the species still lacks, so that its therapeutic compounds can eventually be standardized and clinically validated without costing the species its place on the mountain.

Subject of Research: Optimization of vegetative propagation and in vitro micropropagation protocols for the endangered Himalayan medicinal plant Aquilegia fragrans

Article Title: Optimization of vegetative propagation and micropropagation protocols for the conservation and large-scale cultivation of Aquilegia fragrans Benth

Article References: Bhat, I. A., Guleria, K., Kumari, A., Banoo, S., Kaloo, Z. A., & Fayaz, M. (2026). Optimization of vegetative propagation and micropropagation protocols for the conservation and large-scale cultivation of Aquilegia fragrans Benth. Discover Conservation, 3(1), Article 30. https://doi.org/10.1007/s44353-026-00099-7

Image Credits: AI Generated

DOI: 10.1007/s44353-026-00099-7

Keywords: Aquilegia fragrans, micropropagation, vegetative propagation, gibberellic acid, plant tissue culture, thidiazuron, meta-topolin, rhizome cuttings, medicinal plants, Kashmir Himalaya, plant conservation, vermicompost