Environmental and Earth Sciences

Abstract: Soil degradation is one of the greatest threats to sustainable agriculture, yet current soil health assessment frameworks largely rely on physicochemical indicators and may insufficiently account for crop-specific biological requirements and microbiome functions. Increasing evidence indicates that different crops require distinct combinations of physical, chemical, and biological soil properties and recruit differentially enriched rhizosphere microbial assemblages that regulate nutrient cycling, disease suppression, plant performance, and nutritional quality. This review critically examines current concepts of soil quality and soil health and highlights the need to shift from generalized toward crop-specific soil health assessment. We synthesize the principal physical, chemical, and biological indicators of soil health, with emphasis on soil microbiomes, beneficial microorganisms, soil-borne pathogens, molecular diagnostic approaches, and representative sampling strategies. Using publicly available FAOSTAT and EPPO datasets as an exploratory European case study, we describe continental crop production patterns and the geographical occurrence of major plant pathogens to illustrate how regional crop production and pathogen records can provide context for crop-specific soil health assessment. We further assess evidence linking soil properties and plant-associated microbiomes with crop nutrient composition and bioactive phytochemical accumulation. Collectively, this review proposes a crop-specific conceptual framework that integrates ecological, biological, and agronomic processes to support the interpretation of soil health measurements and provides a basis for future empirical validation.

Abstract: Hyper-arid agricultural soils combine low organic carbon, high calcium carbonate contents, salinity, and frequent gypsum accumulation, making rapid quantification of soil organic carbon (SOC), soil inorganic carbon (SIC), and gypsum valuable but analytically demanding. We evaluated visible–near infrared (VNIR) spectroscopy for predicting these three properties in 216 samples from 18 plots, nested within six oasis sites spanning two oasis management systems, three topographic positions, and six soil depths, with particular emphasis on how validation design affects apparent model accuracy. Partial least squares regression (PLSR) and random forest (RF), single- and multi-target workflows, and global versus stratified calibrations were compared using plot-blocked GroupKFold, site-blocked GroupKFold, random KFold, and leave-one-out cross-validation (LOOCV). Under continuum-removed spectra, RF outperformed PLSR across all three targets. Predictability was strongly target-specific: gypsum was predicted most reliably (R² = 0.78), SOC moderately (R² = 0.44), and SIC least reliably (R² = 0.30). KFold and LOOCV generally yielded more optimistic estimates than plot-blocked GroupKFold, inflating SIC R² by 0.15–0.19 for the global model and by up to 0.64 for stratified models. Site-blocked validation further showed that spatial transferability was strongly target-specific: SOC performance remained similar between plot-blocked and site-blocked validation (R² = 0.41 and 0.43, respectively), gypsum performance declined moderately (R² = 0.78 to 0.64), whereas SIC performance decreased markedly from R² = 0.30 to −0.28, indicating poorer performance than a mean-based prediction under oasis-level blocking. VNIR spectroscopy therefore shows strong potential for gypsum, moderate utility for SOC, but limited transferability for SIC. Validation design, together with the spatial scale at which independence is imposed, critically determines how soil-spectroscopy performance should be interpreted for dryland monitoring.

Abstract: Aided phytostabilization—combining soil amendments with tolerant vegetation—has proven effective improving soil properties and reducing potentially toxic elements (PTE) mobility in polluted soils, yet long-term studies are scarce. This study evaluates the 10-year evolution of an undergoing (aided) phytostabilization field trial at a former Cu mine in Touro (NW Spain), comparing different strategies for soil recovery and PTE immobilization. The mine soil (Spolic Technosol) was extremely acidic, nutrient-depleted, and virtually devoid of vegetation. Three amendments—compost (PC) and two technosols (PT1, PT2)—were assayed. Three planting treatments—Agrostis capillaris, AGR; Salix viminalis, SAL; unplanted, UNP—were established. Soil samples were collected before amendment applications and 1, 2, 3, 6 and 10 years after, then analyzed for pH, total C and N, P_Olsen, CEC_e and exchangeable cations, pseudo-total and readily available PTEs. All amendments immediately improved soil fertility and mitigated Cu availability (up to 3 orders of magnitude), thereby enabling vegetation establishment. Different amendments led to distinct initial trajectories that gradually converged toward a common pattern of long-term soil recovery. Aided phytostabilization effectively restored mine soil functionality for over a decade, but amendment choice should be aligned with site-specific recovery objectives and monitoring plans.

Abstract: Assessment of the ASCS compared to the global systems USDA and WRB, pedological studies were emphasized on North-West Sinai region (El- Tina plain) which have five physiographic units, i. e., sand beach, wet sabkha, dry sabkha, sand plain, and sand dunes. Total area is 2943.27 km² which includes urban, fish bonds, lakes, and water body. The current study concluded that Applied Soil Classification System (ASCS) covered most of the requirements of global systems as well as showing levels and its stratification of soil characteristics of importance in applied aspects and land management, and showing the agricultural determinants.

Abstract: A comparison of five agronomic management sectoral variants was conducted on a spring wheat field (rainfed farming) in Northern Kazakhstan to evaluate grain yield stability and its relationship with soil and crop conditions. Four experimental plots (without replication) involved the combined use of the SoilPoint Soil Booster (SPB) preparation and mineral nitrogen application at rates of 0, 2, 6, or 10 kg N/ha, alongside reduced herbicide application rates. The control plot (located at the field edge) received 20 kg N/ha without SPB application. Analysis of yield data, crop characteristics, results from three soil survey cycles, moisture sensor readings (one per SPB plot), and satellite NDVI data revealed four key findings. First, the SPB-N2 variant demonstrated the best results in terms of both total plot yield and sample cut data: the yield was 3.47 t/ha compared to 2.57 t/ha in the control (an increase of +35.0%). Secondly, the SPB-N2 variant recorded the highest average soil profile moisture index (40.31%), whereas the SPB-N10 variant showed the lowest (35.84%) and experienced the most significant decline in this indicator over the observation period (a drop of 21.29 percentage points). Thirdly, the plot with the highest yield was characterized by the lowest nitrate nitrogen content (13.6 mg/kg) based on the initial survey and did not exhibit the maximum NDVI value (0.37). The SPB-N10 variant had the highest NDVI (0.40) but demonstrated the lowest yield among the SPB-treated plots (3.09 t/ha). Fourthly, a zone of reduced yield was identified that cut across the boundaries of different treatment variants, indicating spatial heterogeneity within the field. Seasonal changes in nutrient content followed a specific pattern: levels of nitrate nitrogen, K₂O, sulfur, Mg, and Mn decreased across all variants. Collectively, these results identify the SPB-N2 variant as the most consistently productive and demonstrate that rankings based on average greenness indices and nitrate content (from the first survey) do not align with rankings based on grain yield. The lack of replication in the experimental design and the use of point measurements for soil moisture make it impossible to definitively attribute the results to the impact of specific agronomic practices or to the plot's general water-retention capacity. This study is relevant to ensuring food security (Goal 2)—given that Kazakhstan is a key grain producer in Central Asia—and to the study of ecosystem sustainability (Goal 15).

Abstract: Soil degradation caused by soil salinization is an important factor affecting global food security. The soda saline–alkali soils in the Songnen Plain suffer from poor soil structure, hard topsoil and alkalized horizons, and high pH and Na⁺ concentrations, which pose a major threat to sustainable agricultural development. However, the development of demand-adapted agricultural machinery and agronomic technologies integrating physical and chemical amelioration remains a challenge for soda saline–alkali soil improvement under rain-fed dryland conditions. Based on the water solubility of aluminum sulfate, this study integrated novel equipment and technologies for efficient, engineering-oriented amelioration of soda saline–alkali soils. Experiment analysis of aluminum sulfate application rate experiments showed that the optimal amelioration effect was achieved at an ameliorant dosage of 0.6% of soil dry weight, with a pH reduction of 0.81 units. By means of installing liquid ameliorant spraying components on the base subsoiling machine, it was developed that integrated equipment for simultaneous subsoiling and ameliorant application across the entire plow layer was developed. Verification tests demonstrated that the soil disturbance coefficient, soil loosening degree, and coefficient of variation for liquid application uniformity among rows were 53.75%, 13.50%, and 4.83%, respectively; these operational performance indicators met the requirements of relevant industry standards. Comparisons of soil physicochemical properties under different amelioration treatments revealed that subsoiling combined with ameliorant spraying (SAS) outperformed subsoiling alone (S), surface ameliorant application (A), and the control (CK). Relative to CK, the SAS treatment increased soil water infiltration rate (WIR) by an average of 63.11%, reduced bulk density (BD) by 0.14 g/cm³, decreased pH by 0.86 units, and lowered soil salt content (SC) by 0.71 g/kg. Three-year field alfalfa cultivation experiments indicated that SAS increased alfalfa emergence rate, dry matter yield, and overwintering rate by 20.60%, 26.45%, and 20.29%, respectively, relative to CK. This study proposes an implementation strategy for integrated physical and chemical amelioration equipment and technologies for soda saline–alkali soils based on the SAS approach, which provides equipment, technical, and engineering application references for improving soil health, boosting crop yield, and promoting the efficient utilization of rain-fed soda saline–alkali land.

Abstract: A field experiment was conducted in 2020–2022 at the Czesławice Experimental Farm (Lublin Voivodeship, Poland) to investigate the chemical properties and enzymatic activity of loess soil under oat cultivation, as well as crop productivity (grain yield and grain protein content). The first experimental factor was the farming system: (A) an organic system, without chemical plant protection products or NPK mineral fertilization (only the Humac Agro fertilizer, approved for organic farming, was applied); and (B) a conventional system, with chemical plant protection and NPK mineral fertilization at rates recommended for oat. The second factor comprised different forecrops for oat: potato, spring barley, narrow-leafed lupine, oat, and winter wheat. The organic system had a more fa-vorable effect on the soil contents of organic carbon (by 0.08 percentage points, pp), mag-nesium (by 10%), boron (by 13%), and zinc, manganese, and copper (by 5.5%, 18%, and 7%, respectively), and promoted higher soil enzymatic activity, with increases ranging from 9–14% (for alkaline phosphatase, urease, dehydrogenase) to 32–39% (for acid phos-phatase and protease). In contrast, the conventional system favored soil nitrogen, phosphorus, and potassium contents (increases of 0.02 pp, 12%, and 25%, respectively). The total sorption capacity of the soil was significantly higher under the organic system (by approximately 6%), particularly in interaction with potato as the forecrop (40.9 cmol(+) kg⁻¹). The forecrops such as potato and narrow-leafed lupine had a more beneficial effect on soil quality and oat productivity than the cereal forecrops. Oat grain yield under the organic system was, on average, only 8% lower than under the conventional system. When favorable root-crops and legume forecrops were used, the productivity of organically grown oat matched that of oat grown conventionally after cereal forecrops. Organic oat cultivation resulted in a significantly higher grain protein content.

Abstract: Soil carbon dynamics and fertility may respond differently to land-use systems in the Brazilian semiarid region due to its high environmental and edaphic heterogeneity. This study evaluated soil attributes in degraded, forest, and restoration areas across the states of Ceará (CE), Paraíba (PB), Pernambuco (PE), and Piauí (PI). Surface soil samples (0–10 cm) were analyzed for particle-size distribution, pH, total organic carbon (TOC), humic fractions, available phosphorus, exchangeable cations, and cation exchange capacity (CEC). Soil responses to land use varied markedly among states. Forest areas showed 12% and 57% higher TOC than degraded areas in PB and PI, respectively. Restoration areas showed substantial changes in specific carbon fractions; in PB, humic acid carbon was approximately 85–95% higher and humin carbon 136% higher than in the degraded area. Available phosphorus was also markedly higher in restoration areas in PB and PI. In PI, the restoration area was characterized by high Ca²⁺ and Mg²⁺ contents and CEC, whereas soil pH ranged from approximately 5.0 in the forest area to 8.0 in the degraded area. Overall, restoration areas showed improvements in specific soil attributes, although the magnitude and direction of these responses were strongly modulated by local edaphic conditions.

Abstract: Irrigation-water quality and soil physical properties influence water movement through agricultural soils, but their interactions under field irrigation conditions remain poorly characterized in Eastern Africa. This study evaluated irrigation-water quality, soil physicochemical properties, and infiltration behaviour in the Kagitumba and Nasho Government-Funded Irrigation schemes in Eastern Rwanda. A comparative observational design was applied at 20 sampling locations per scheme. Soil samples were collected at 0–30 and 30–60 cm depths, and 20 irrigation-water samples were collected from each scheme. Soil properties and irrigation-water quality were analysed using standard laboratory and field methods. Infiltration was measured using a double-ring infiltrometer and described using the Horton model. Paired-samples t-tests and Spearman rank correlations were used for statistical analysis. Both schemes had predominantly sandy-loam soils, but soil physical properties differed between schemes and depths. Bulk density ranged from 0.751–0.896 g cm⁻³ at Kagitumba and 1.31–1.33 g cm⁻³ at Nasho. Mean irrigation-water electrical conductivity was 0.319 and 0.324 dS m⁻¹, respectively. Turbidity was higher at Kagitumba than at Nasho. Steady-state infiltration rates were 0.8 and 1.2 cm h⁻¹, respectively. Significant depth-related differences occurred in several soil properties. Infiltration was significantly associated with water electrical conductivity and oxidation–reduction potential only at Nasho, while turbidity was not significantly associated with infiltration at either scheme. Soil properties and infiltration behaviour showed substantial site-specific and depth-related variability. Integrating depth-resolved soil characterization with irrigation-water quality assessment is important for understanding soil–water interactions and improving irrigation management in sandy-loam soils.

Abstract: Digestate is a by-product of the anaerobic digestion of food waste and can be used as a fertilizer for agricultural production. The partial replacement of mineral fertilizers with food waste digestate represents a promising strategy to improve soil fertility and enhance plant nutrition and growth. Therefore, this study evaluated the effects of dif-ferent proportions of digestate derived from the anaerobic digestion of food waste combined with mineral fertilization on soil fertility, growth, and nutritional status of maize (Zea mays L.) plants. The experiment was conducted in a greenhouse using a completely randomized design with six treatments: unfertilized control (C0), 100% mineral fertilizer (M100), 75% mineral fertilizer + 25% digestate (M75D25), 50% min-eral fertilizer + 50% digestate (M50D50), 25% mineral fertilizer + 75% digestate (M25D75), and 100% digestate (D100), with four replicates. The M25D75 treatment significantly increased cation exchange capacity, base saturation, and pH, also result-ing in higher concentrations of P and Mg in the soil. Furthermore, this treatment pro-moted higher chlorophyll index, stem diameter, leaf number, plant height, and dry biomass, as well as increased plant concentrations of P, K, Ca, and Mg. In contrast, the exclusive application of digestate (D100) increased electrical conductivity, exchangea-ble sodium percentage, and sodium concentrations in both soil and plants, leading to reduced plant growth. Multivariate analysis confirmed the association of the M25D75 treatment with simultaneous improvements in soil fertility, plant nutrition, and plant growth. The combined application of mineral fertilizers and digestate improved soil fertility, plant nutrition, and plant growth, allowing up to 75% of the mineral fertilizer to be replaced by food waste digestate. These findings support the sustainable recycling of food waste through its agricultural use as digestate, contributing to circular nutrient management and reducing dependence on synthetic mineral fertilizers.

Abstract: Corporate carbon offsetting schemes heavily rely on tree planting for carbon sequestration, and in Scotland the government presents tree planting as a key carbon sink in the face of climate change. However, carbon offsetting schemes rarely consider associated fluxes in soil organic carbon (SOC) driven by afforestation. Soils in woodlands store approximately 75% of the total ecosystem carbon, yet planting trees on existing carbon-rich soils or grassland may result in changes in soil carbon that take decades for tree biomass to recover. This study provides a methodological framework using the chronosequence approach (space-for-time substitution) to measure whole-ecosystem carbon storage for existing commercial carbon sequestration schemes. A proof-of-concept pilot study was carried out at the University of Edinburgh’s Rullion Green site, gathering 35 soil samples across unplanted baselines, a recent 2025 planting scheme, and a mature mixed woodland. The findings of this proof-of-concept study show that soil carbon in the newly planted area (5.06% SOC) was lower than in the mature woodland (7.64% SOC) and remained statistically similar to the unplanted baseline (7.11-8.65% SOC depending on slope). The carbon in the recently planted trees (4.10 t C/ha) did not offset the carbon losses from soil, with a drop in ecosystem carbon of 156.41 t C/ha compared to the baseline, and 418.23 t C/ha compared to the mature woodland. The methodology and trial study suggest that initial tree planting may not guarantee an immediate net increase in ecosystem carbon until trees become mature. The methodology therefore provides a tool to help mitigate greenwashing in the offsetting industry. The methodology will now be applied in further research to other sites across northern England to determine what the impact of tree planting for carbon sequestration is on soil in the UK.

Abstract: Afforestation is widely used to restore degraded Mediterranean landscapes, yet restoration success is often evaluated using vegetation establishment or soil carbon accumulation, with less attention to belowground ecosystem functioning. We assessed whether Cedrus libani afforestation promotes soil functional recovery in degraded Mediterranean karst and whether structural and microbial indicators provide robust measures of restoration progress under edaphic heterogeneity. Topsoil (0–10 cm) was sampled from degraded non-afforested reference land and 10-, 15-, and 25-year-old plantations in southern Türkiye. Soil organic carbon (SOC), total nitrogen (TN), aggregate stability, microbial biomass carbon (MBC), basal respiration, microbial quotient (qMic), and metabolic quotient (qCO₂) were determined. Afforested soils had higher SOC (1.55% vs. 2.37–3.35%), TN (0.053% vs. 0.087–0.190%), aggregate stability (61.3% vs. 77.8–84.9%), and MBC (180 vs. 288–536 µg g⁻¹), whereas basal respiration declined from 0.96 to 0.30–0.36 µg CO₂–C g⁻¹ h⁻¹ and qCO₂ from 5.41 to 0.54–1.39. qMic did not differ significantly among chronosequence classes. MBC was strongly associated with SOC (ρ = 0.917, P < 0.001) but not with basal respiration (ρ = −0.075, P = 0.57). Sensitivity analyses accounting for carbonate content and pH showed that aggregate stability, basal respiration, and qCO₂ were comparatively robust, whereas SOC, TN, and MBC responses were partly substrate-dependent. Multivariate analyses revealed coordinated but non-monotonic shifts across the chronosequence. These findings indicate that restoration outcomes in Mediterranean karst cannot be assessed from carbon accumulation alone and that integrating microbial metabolic and structural indicators with edaphic information provides a more informative framework for monitoring afforestation success.

Abstract: Increasing soil contamination by potentially toxic elements (PTEs) threatens environmental quality and ecosystem health, reinforcing the need for effective remediation strategies. Phytoremediation uses plants to remove, immobilize, or neutralize contaminants and represents a sustainable approach for restoring contaminated soils. Although nickel (Ni) is an essential plant micronutrient, elevated concentrations can cause phytotoxicity. This review synthesized data from field and controlled-condition studies on the effects of soil Ni concentrations and the phytoremediation performance of plant species. A Web of Science search identified 230 studies, of which 94 met the predefined inclusion criteria. Plant responses varied according to species and Ni concentration. More than 86% of the 449 plant records corresponded to herbaceous plants; Poaceae accounted for over 26% of the reported Ni-phytoremediating taxa, followed by Brassicaceae at approximately 18%. Brassica juncea showed the most consistent performance, combining Ni tolerance with phytoextraction and hyperaccumulation. Alyssum murale exhibited the highest phytoextraction capacity and the highest Ni concentration among the hyperaccumulators. Overall, the reviewed evidence supports phytoremediation as a sustainable strategy for Ni-contaminated environments. However, further research is required to support large-scale implementation and ensure alignment with global environmental sustainability objectives.

Abstract: Next-generation sequencing (NGS) has transformed soil microbial ecology by revealing taxonomic and functional diversity that was largely inaccessible through cultivation-based approaches. However, greater sequencing resolution alone does not explain why particular microbial assemblages repeatedly emerge under specific soil and environmental conditions. This review examines the current state of NGS-based soil microbiome characterization and introduces Hierarchical Environmental Filtering (HEF) as a framework for interpreting microbial community assembly. We discuss advances from amplicon sequencing to shotgun metagenomics, long-read sequencing, multi-omics, and computational analysis, together with limitations related to sampling, DNA extraction, primer selection, sequencing depth, bioinformatics, reference databases, and relic DNA. Within HEF, pedogenesis establishes the physicochemical template for microbial assembly, while climate, vegetation, rhizosphere processes, and biological interactions act as secondary filters. Anthropogenic disturbances may modify or partially override these natural filters, promoting community reassembly and ecological convergence. Soil microbiomes should therefore be interpreted as dynamic outcomes of environmental selection across spatial and temporal scales. Integrating standardized NGS workflows with functional multi-omics and predictive computation should advance soil microbiome research from descriptive inventories toward a mechanistic understanding of community assembly.

Abstract: Climate change poses one of the greatest threats to the sustainability of rainfed agriculture in Latin America, where common bean (Phaseolus vulgaris L.) production is particularly vulnerable because of its high sensitivity to fluctuations in temperature and precipitation, as well as to extreme climatic events. This scoping review aimed to examine the evolution of scientific research on the impacts of climate change on the sustainability of rainfed common bean production in Latin America by identifying geographic and temporal research trends, methodological approaches, major scientific advances, knowledge gaps, and future research priorities. The review followed the Joanna Briggs Institute (JBI) methodological framework and the PRISMA-ScR reporting guidelines and included 154 peer-reviewed studies published in indexed journals. The evidence was synthesized by country, publication period, and methodological approach, encompassing field experiments, agroclimatic assessments, crop-simulation models, Geographic Information Systems (GIS), remote sensing, review articles, meta-analyses, and farmer surveys. The results revealed that scientific production was concentrated primarily in Mexico and Brazil, whereas research in the remaining Latin American countries remained limited and geographically fragmented. Over time, the field evolved from studies focused primarily on crop physiology and genetic improvement toward multidisciplinary approaches integrating climatic, agronomic, environmental, and socioeconomic perspectives. Despite these advances, important knowledge gaps remain, particularly the limited availability of long-term field experiments and the insufficient integration of environmental, economic, and social dimensions into climate adaptation research. This review provides a comprehensive regional synthesis of the available scientific evidence on climate change and rainfed common bean production in Latin America, offering a solid evidence base to guide future research, inform climate adaptation strategies, and strengthen the resilience and sustainability of rainfed common bean production systems.

Abstract: Unavailability of inexpensive, reliable and smart health monitoring system for the soil and growing agricultural crop in developing countries like India is the major constraint for economic productivity and self-sufficiency in agro-products. To address such a burning issue, the present paper proposes an IoT based solar powered, inexpensive smart sensory system, for in situ and ex situ health monitoring of agricultural soil and growing crops. Here, the proposed system uses a single sensing mechanism to monitor the nitrate concentration in the roots of the crop as well as pH of soil. Additionally, the system has been integrated to measure all the ambient parameters detrimental to plant and soil health. The features including auto compensation of the measured parameters against temperature and humidity variations, auto calibration of the sensory systems adds smartness to the device. All the measurands were compared with the respective standard instruments and for all the measurements, readings were highly correlated with R2-value ranging from 0.98 to 0.99.The performance of the device was checked in the field and the results obtained were very satisfactory.

Abstract: Long-term field trials are important for evaluating the environmental and economic sustainability of crop and soil management practices. The current study evaluated differences in soil organic carbon (SOC), total nitrogen (N), extractable phosphorus (P) and pH across tillage and straw management systems of dryland wheat monocrop after approximately 40 years (1979 - 2018) of experimentation on an acric plinthosol. The study also determined the effects of tillage, straw management and N fertiliser rate on wheat grain yield after every 10 years over 40 years. Treatments consisted of plots under conventional tillage (CT), stubble mulch (SM) and no-tillage (NT), combined with either straw burning (burned) or retention (not burned). Nitrogen fertiliser rates tested were 20, 40 and 60 kg N ha^-1. Straw burning (p < 0.05) increased soil pH significantly and Bray-1 extractable P under NT, but not in other tillage systems. The Bray-1 extractable P declined down the profile, regardless of tillage or straw management. Total soil N was higher under NT than other tillage practices but did not vary with straw management, while SOC was not significantly affected by tillage or straw management. Wheat grain yield was significantly increased by higher N fertiliser levels and wetter seasons over the years. The findings suggest that after 40 years of practice, the main driving factors for wheat yield in the low-input dryland monocropping system, under semi-arid conditions, are N fertiliser and seasonal rainfall; hence, farmers may benefit by considering supplementary irrigation during drier years. Furthermore, no-till could be beneficial to improve total N. When combined with straw burning, it also increases soil pH and P, but an alternative strategy for sustainable SOC build-up needs to be sought for this soil type under semi-arid conditions.

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The increasing demand for food production has intensified the use of chemical fertilizers, raising concerns about their environmental impact. Plant Growth-Promoting Bacteria (PGPB) have emerged as a sustainable alternative; however, many studies are conducted under highly controlled conditions which do not accurately represent real agricultural systems. This study evaluated the effect of microbial consortia comprising of Azospirillum brasilense, Pseudomonas putida, Bacillus sp., and Mycobacterium sp. on plant growth under contrasting substrate conditions (commercial substrate and greenhouse soil). Their biostimulant potential was assessed in Zea mays (blue maize), Brassica oleracea (broccoli), and Solanum lycopersicum (tomato). The assessment included measurements of root and shoot elongation as well as dry biomass. The results demonstrated that microbial consortia significantly (p=0.01) improved plant growth compared to the control across all species. Among the treatments, the consortium Pseudomonas putida + Bacillus sp. had the best results by presenting significantly (p=0.01) higher values in root length, stem growth, and dry weight in both substrate types. Additionally, consortia containing Mycobacterium sp. demonstrated enhanced performance in greenhouse soil, particularly in biomass accumulation for Zea mays and Brassica oleracea. These results highlight the importance of selecting appropriate microbial combinations and validating their performance in environments that reflect practical agricultural conditions.

Abstract: The expansion of anaerobic digestion has created two linked opportunities: renewable-energy production and the return of nutrients and organic matter to land. It has also created an agronomic problem that cannot be solved by calling every residual material a biofertilizer. Digestate varies with feedstock, digestion conditions, separation, storage, post-treatment and the point at which it is sampled. Its value therefore emerges only when product composition is connected to crop demand, soil conditions, application practice and the environmental pathways that remain open after land application. This structured critical narrative review brings together evidence on crop production, nutrient replacement, soil physical and biological responses, greenhouse-gas emissions, nutrient losses, contaminants, processing and practical implementation. Greatest interpretive weight is given to inspectable original studies and replicated field evidence; reviews and meta-analyses are used to identify consistency and heterogeneity, not counted as additional experiments.The major points are the following. First, whole and processed digestates can replace part of a mineral-fertilizer programme, but the replacement value belongs to the complete product-management-soil-crop system rather than to digestate as a universal material. Trials that appear to compare equal fertilizer rates often match different quantities of total N, ammonium-N, estimated available N, P, K, S, organic N and carbon, and they frequently differ in mineral-fertilizer formulation, application timing and placement. Yield equivalence is therefore not automatically nutrient equivalence. Second, the product fraction matters. Liquid fractions commonly act as rapid N and K sources, whereas separated solids retain more particulate carbon and phosphorus and may release N more slowly. Third, long-term soil responses are real but conditional. Multi-year studies range from little detectable difference relative to slurry or mineral fertilizer to increases in soil-carbon pools under particular combinations of product, soil, crop, dose and management. Concentration changes, short incubations and degraded-soil demonstrations should not be treated as universal proof of durable stock change.Fourth, environmental performance cannot be represented by one emission factor or one safety label. Ammonia loss depends on pH, total ammoniacal N, dry matter, viscosity, storage, weather and surface exposure; nitrous oxide depends strongly on soil moisture, native mineral N, degradable carbon, placement and management history. Practices that reduce one pathway can increase another. Anaerobic digestion does not destroy metals, and evidence on pharmaceuticals, PFAS precursors, microplastics, phytotoxicity and antimicrobial resistance shows alteration of concentration, partitioning, viability or exposure rather than guaranteed removal. The central conclusion is consequently practical rather than promotional: digestate can be a valuable nutrient and, in some products and settings, carbon resource when it is characterized, matched to crop and soil requirements, applied with control of loss pathways and monitored over an appropriate timescale. It is neither intrinsically safe nor uniformly effective, but neither should it be dismissed as a waste when evidence-based management can recover useful functions.

Abstract: The rice-wheat cropping system under Vertisol in sub-tropical regions of India faces significant challenges in maintaining soil health and achieving sustainable yields. This is primarily due to climatic variability and intensive agricultural practices, which accelerate the loss of soil organic carbon (SOC) and lead to soil degradation. There is a pressing need to adopt sustainable nutrient management, that not only maximize crop yields but also support climate change mitigation through carbon (C) sequestration and soil health management. In this context, a long-term fertilizer management (25 years) study was undertaken to assess crop productivity, C fractions, sequestration potential to achieve soil C 4 per mille under rice-wheat cropping system in sub-tropical Vertisol. The experiment was based on ten different fertilizer treatments either alone or in combination with organics. Grain yield, system productivity, and the sustainable yield index (SYI) were significantly higher under the 150%NPK and NPK + Farmyard manure (FYM) treatments compared to the unfertilized control. Relying on imbalanced fertilization (N) is inadequate for long-term sustainability. Long-term application of 100% NPK+FYM increased SOC content by up to 16%, whereas it decreased by 34% under absolute control relative to the initial value. Integrated nutrient management (INM) significantly enhanced the SOC pools, with higher proportion (57%) of total SOC in passive C pools. The increase in SOC stock was significantly correlated (R² = 0.76) with system productivity, requiring a minimum C input of 2.7 Mg C ha^-1 yr^-1 to maintain C equilibrium. The INM treatment achieved the highest C sequestration (2.27 Mg ha^-1), potential (7.04 Mg ha^-1) and rate (0.10 Mg C ha^-1 yr^-1) compared to NPK. In the present study, the C sequestration rate under NPK+FYM and 150%NPK surpassed the annual increment requirement of 0.4% SOC to achieve the target of the “4 per mille”. Over 25 years, application of 5 Mg ha^-1 FYM with NPK proved to be the most sustainable practice for SOC management. In addition to enhancing SOC stock, this practice maximizes crop productivity, thereby highlighting the potential of soil management as an effective voluntary carbon sequestration pathway for climate-change mitigation strategy in sub-tropical regions.