Soil Systems

18 pages, 2690 KB

Open AccessArticle

Precision Fertilization Strategies Modulate Growth, Physiological Performance, and Soil–Plant Nutrient Dynamics in Sabal palmetto

by Amir Ali Khoddamzadeh, Bárbara Nogueira Souza Costa and Milagros Ninoska Munoz-Salas

Soil Syst. 2025, 9(4), 121; https://doi.org/10.3390/soilsystems9040121 - 6 Nov 2025

Abstract

Optimizing fertilizer management is essential for reducing salinity-related risks and improving nutrient efficiency in ornamental plant production. Fertilization enhances plant performance; however, excessive nutrient inputs can disrupt substrate chemistry, elevate salinity, and promote nitrogen leaching—particularly in containerized systems with limited rooting volume. This [...] Read more.

Optimizing fertilizer management is essential for reducing salinity-related risks and improving nutrient efficiency in ornamental plant production. Fertilization enhances plant performance; however, excessive nutrient inputs can disrupt substrate chemistry, elevate salinity, and promote nitrogen leaching—particularly in containerized systems with limited rooting volume. This study evaluated the growth, physiological performance, and soil–plant nutrient dynamics of Sabal palmetto (cabbage palm) cultivated under six fertilization regimes over 180 days in a subtropical shade-house environment. Treatments ranged from a single baseline application of 15 g per plant (T0) to a cumulative 75 g (T5) using granular slow-release fertilizer. Morphological traits (plant height: 26–70 cm; leaf number: 4–18) and physiological indices (atLEAF⁺: 34.3–66.4; NDVI: 0.26–0.77) were monitored every 30 days. Substrate nitrogen and carbon concentrations increased from 0.57% and 41.78% at baseline to 1.24% and 42.94% at 180 days, while foliar nitrogen ranged from 1.46% to 2.57%. Fertilization significantly influenced all parameters (p < 0.05). Higher fertilization levels elevated electrical conductivity, salinity, and nitrogen leaching, with principal component analysis revealing strong positive associations among total nitrogen, electrical conductivity, and salinity. Moderate fertilization (T2 = 45 g) maintained favorable substrate chemistry, high foliar nitrogen, and balanced canopy growth with minimal nutrient losses. Sensor-based chlorophyll indices (atLEAF⁺ and NDVI) correlated strongly (r = 0.71, p < 0.001), confirming their reliability as non-destructive diagnostics for nitrogen management. These findings demonstrate that integrating optical monitoring with adaptive fertilization mitigates substrate salinization, sustains ornamental quality, and promotes the sustainable cultivation of Sabal palmetto in urban horticultural systems. Full article

(This article belongs to the Special Issue Advances in the Prediction and Remediation of Soil Salinization: 2nd Edition)

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20 pages, 6954 KB

Open AccessArticle

Early Peat Diagenesis Controls on Bromine Accumulation

by Antonio Martínez Cortizas, Mohamed Traoré, Olalla López-Costas, Géraldine Sarret and Stéphane Guédron

Soil Syst. 2025, 9(4), 120; https://doi.org/10.3390/soilsystems9040120 - 5 Nov 2025

Abstract

Peatlands are natural reservoirs of organobromine compounds. Important advances have been made in unraveling the mechanisms involved in bromine (Br) retention in the peat but, to our knowledge, the temporal and spatial variation of the peat organic matter (OM) bromination has not been [...] Read more.

Peatlands are natural reservoirs of organobromine compounds. Important advances have been made in unraveling the mechanisms involved in bromine (Br) retention in the peat but, to our knowledge, the temporal and spatial variation of the peat organic matter (OM) bromination has not been fully researched. Here, we present the study of 12 short cores (c. 30 cm, c. 150–200 years of peat accumulation) sampled from a small (c. 1 ha) area of an oceanic blanket peatland from northwestern Spain. We combine Br concentrations, spectroscopic analysis (FTIR–ATR), and structural equation statistical modelling (SEM). Our results show that Br is significantly correlated to proxies of peat aerobic decomposition, with concentrations increasing with depth in all cores (×2–10 times). Strong spatial heterogeneity was observed, with some cores showing much higher Br maximum concentrations and larger increases with depth. SEM modelling indicated that various OM functionalities contribute to Br accumulation and that their effects change with depth/age, with aromatics becoming dominant after 20–90 years. Thus, changes in organic matter molecular composition, linked to early peat diagenesis, and the geochemical conditions governing it exerted a strong control on Br accumulation in the studied peatland. Bromine wet deposition was not found to be a limiting factor. Full article

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19 pages, 13114 KB

Open AccessArticle

Transient Effects of Biochar and Drainage Systems on Soil Granulometry, Bulk Density, and Porosity in Clay Loam Anthrosols Under Monsoon Climate

by Anastasia Brikmans, Olga Nesterova, Andrei Egorin, Mariia Bovsun, Viktoriia Semal and Nikolay Sakara

Soil Syst. 2025, 9(4), 119; https://doi.org/10.3390/soilsystems9040119 - 5 Nov 2025

Abstract

Heavy-textured soils in monsoon-affected regions face challenges related to waterlogging and structural degradation, yet the long-term efficacy of biochar as a physical soil amendment under such conditions remains inadequately understood. This two-year field study (2018–2019) therefore evaluated the transient impacts of birch-derived biochar [...] Read more.

Heavy-textured soils in monsoon-affected regions face challenges related to waterlogging and structural degradation, yet the long-term efficacy of biochar as a physical soil amendment under such conditions remains inadequately understood. This two-year field study (2018–2019) therefore evaluated the transient impacts of birch-derived biochar (360–380 °C pyrolysis; 0, 1, 3 kg/m²), subsurface drainage systems, and fertilizer regimes on key physical properties of Endoargic Anthrosols (clay loam) in coastal Primorsky Krai, Russia. Granulometric composition remained stable (silt loam: sand 42–48%, silt 38–44%, clay 12–16%), though drainage significantly increased the silt fraction by >7.5% (p < 0.05). Biochar induced short-term reductions in bulk density (ρ_b; max −12% at 3 kg/m², 2018) and aggregate density (ρ_a; max −9.3%, 2018), but these effects dissipated by 2019 due to tillage redistribution and monsoonal fragmentation, as verified by SEM. Total porosity fluctuated seasonally (0.50–0.65 cm³/cm³), peaking post-tillage but declining under monsoon saturation, with no significant sustained biochar contribution. Crucially, intra-aggregate pore architecture (2–50 nm) resisted amendment-induced changes; N₂ adsorption showed treatment-invariant mesopore dominance (65–75% volume; mean pore diameter 17–21 nm), attributable to biochar’s physical exclusion (>1 µm particles from sub-0.5 µm pores) and inert fragmentation. Drainage dominated structural dynamics, modulating pore volume seasonally (−15% in 2018; +18% in 2019), while organic fertilizer enhanced porosity through polysaccharide-stabilized microaggregation (+22%, 2019). We conclude that biochar’s physical benefits in clay loams under monsoon climates are transient and dose-dependent, operating primarily through inter-aggregate macroporosity rather than intra-aggregate modification, necessitating reapplication for sustained improvements. Full article

(This article belongs to the Special Issue Research on Soil Management and Conservation: 2nd Edition)

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18 pages, 2682 KB

Open AccessArticle

Soil Management and Machine Learning Abandonment Detection in Mediterranean Olive Groves Under Drought: A Case Study from Central Spain

by Giovanni Marchese, Juan E. Herranz-Luque, Sohail Anwar, Valentina Vaglia, Chiara Toffanin, Ana Moreno-Delafuente, Blanca Sastre and María José Marqués Pérez

Soil Syst. 2025, 9(4), 118; https://doi.org/10.3390/soilsystems9040118 - 31 Oct 2025

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Abstract

In Mediterranean semi-arid regions, rainfed olive groves are increasingly being abandoned due to drought, low profitability, and rural depopulation. The long-term impact of abandonment on soil conditions is debated, as it may promote vegetation recovery or lead to degradation. In contrast, some farmers [...] Read more.

In Mediterranean semi-arid regions, rainfed olive groves are increasingly being abandoned due to drought, low profitability, and rural depopulation. The long-term impact of abandonment on soil conditions is debated, as it may promote vegetation recovery or lead to degradation. In contrast, some farmers are adopting low-disturbance management practices that allow spontaneous vegetation to establish. These contrasting scenarios offer valuable opportunities for comparison. This study aims to develop a framework to assess the impact of different management regimes on soil health and to investigate (1) the impact of spontaneous vegetation cover (SVC) and tillage regimes on soil organic carbon (SOC), and (2) the long-term ecological dynamics of abandoned groves, through a combination of field surveys, remote sensing, and object detection. SOC was assessed using both ground-based and remote sensing-derived indicators. Vegetation cover was quantified via a grid point intercept method. Field data were integrated with a land-use monitoring framework that includes abandonment assessment through historical orthophotos and a deep learning model (YOLOv12) to detect active and abandoned olive groves. Results show that abandoned zones are richer in SOC than active ones. In particular, the active groves with SVC exhibit a mean SOC of 1%, which is higher than that of tilled groves, where SOC is 0.45%, with no apparent moisture loss. Abandoned groves can be reliably identified from aerial imagery, achieving a recall of 0.833 for abandoned patches. Our results demonstrate the potential of YOLOv12 as an innovative and accessible tool for detecting zones undergoing ecological regeneration or degradation. The study underscores the ecological and agronomic potential of spontaneous vegetation in olive agroecosystems. Full article

(This article belongs to the Special Issue Research on Soil Management and Conservation: 2nd Edition)

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2 pages, 139 KB

Open AccessCorrection

Correction: Hazratqulov et al. Processing Municipal Waste for Phytostabilization of Heavy Metal Contaminated Soils. Soil Syst. 2024, 8, 109

by Shohnazar Hazratqulov, Georgina von Ahlefeldt, Rui Liu, Holger Bessler, Hernán Almuina-Villar, Alba Dieguez-Alonso and Christof Engels

Soil Syst. 2025, 9(4), 117; https://doi.org/10.3390/soilsystems9040117 - 28 Oct 2025

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Abstract

In the original article [...] Full article

32 pages, 7132 KB

Open AccessArticle

Synthetic Bacterial Consortium Induces Dynamic Shifts in Fungal Community and Alters Microbial Network Topology in Barley Soil Under Field Conditions

by Roderic Gilles Claret Diabankana, Ernest Nailevich Komissarov, Daniel Mawuena Afordoanyi, Bakhtiyar Islamov, Artemiy Yurievich Sukhanov, Elena Shulga, Maria Nikolaevna Filimonova, Keremli Saparmyradov, Natalia V. Trachtmann and Shamil Z. Validov

Soil Syst. 2025, 9(4), 116; https://doi.org/10.3390/soilsystems9040116 - 19 Oct 2025

Viewed by 528

Abstract

Microorganisms are fundamental drivers of soil productivity, mediating nutrient cycling and pathogen suppression. In this study, we evaluated changes in the fungal community in the soil of barley (Hordeum vulgare L.) in a field experiment involving the application of a consortium of [...] Read more.

Microorganisms are fundamental drivers of soil productivity, mediating nutrient cycling and pathogen suppression. In this study, we evaluated changes in the fungal community in the soil of barley (Hordeum vulgare L.) in a field experiment involving the application of a consortium of Paenibacillus pabuli, Priestia megaterium, Pseudomonas koreensis, and Pseudomonas orientalis. Seed pretreatment and seed pretreatment followed by rhizosphere drenching at different growth stages were implemented. Regarding fungal communities in bulk soil, the rhizospheres of untreated and treated plants were characterized based on full-length ribosomal RNA gene (18S-5.8S-28S) metabarcoding sequencing. Despite the compositional shifts, no statistical differences were observed among the alpha diversity metrics. Seed treatment resulted in long-term, targeted suppression of Fusarium graminearum, Fusarium fujikuroi, Fusarium musae, and Fusarium verticillioides from the booting through flowering and dough development stages, outperforming seed pretreatment followed by rhizosphere drenching. A low-modularity network was observed in the rhizosphere of untreated plants. Seed treatment fostered a highly interconnected and uniform network with low hub-betweenness scores. Rhizosphere drenching of pretreated seeds shifted the network topology toward higher hub-betweenness scores, reducing their connectivity by up to 10% in the rhizosphere and bulk soil. These findings provide a framework for optimizing the soil ecosystem for sustainable agriculture. Full article

(This article belongs to the Topic Interactions between Plants and Soil Microbes in Natural Ecosystem)

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19 pages, 1334 KB

Open AccessArticle

Spatial Decoupling of Biological and Geochemical Phosphorus Cycling in Podzolized Soils

by Daniel F. Petticord, Benjamin T. Uveges, Elizabeth H. Boughton, Brian D. Strahm and Jed P. Sparks

Soil Syst. 2025, 9(4), 115; https://doi.org/10.3390/soilsystems9040115 - 16 Oct 2025

Viewed by 310

Abstract

Phosphorus (P) is essential to life yet constrained by finite reserves, heterogeneous distribution, and strong chemical binding to soil minerals. Pedogenesis progressively alters the availability of P: in ‘young’ soils, P associated with Ca and Mg is relatively labile, while in ‘old’ soils, [...] Read more.

Phosphorus (P) is essential to life yet constrained by finite reserves, heterogeneous distribution, and strong chemical binding to soil minerals. Pedogenesis progressively alters the availability of P: in ‘young’ soils, P associated with Ca and Mg is relatively labile, while in ‘old’ soils, acidification and leaching deplete base cations, shifting P into organic matter and recalcitrant Al- and Fe-bound pools. Podzolized soils (Spodosols) provide a unique lens for studying this transition because podzolization vertically segregates these dynamics into distinct horizons. Organic cycling dominates the surface horizon, while downward translocation of Al, Fe, and humus creates a spodic horizon that immobilizes P through sorption and co-precipitation in amorphous organometal complexes. This spatial separation establishes two contrasting P pools—biologically dynamic surface P and mineral-stabilized deep P—that may be variably accessible to plants and microbes depending on depth, chemistry, and hydrology. We synthesize mechanisms of spodic P retention and liberation, including redox oscillations, ligand exchange, root exudation, and physical disturbance, and contrast these with strictly mineral-driven or biologically dominated systems. We further propose that podzols serve as natural experimental models for ecosystem aging, allowing researchers to explore how P cycling reorganizes as soils develop, how vertical stratification structures biotic strategies for nutrient acquisition, and how deep legacy P pools may be remobilized under environmental change. By framing podzols as a spatial analogue of long-term weathering, this paper identifies them as critical systems for advancing our understanding of nutrient limitation, biogeochemical cycling, and sustainable management of P in diverse ecosystems. Full article

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14 pages, 917 KB

Open AccessArticle

Improving Chernozem Fertility and Barley Yield Through Combined Application of Phosphorus Fertilizer and Ash–Carbon Amendment

by Abilzhan Khussainov, Anara Sarsenova, Anar Ayapbergenova, Gulmira Kyzdarbekova and Ekaterina Bazilevskaya

Soil Syst. 2025, 9(4), 114; https://doi.org/10.3390/soilsystems9040114 - 16 Oct 2025

Viewed by 216

Abstract

Phosphorus deficiency and declining organic matter limit crop productivity in Northern Kazakhstan’s chernozem soils. This study evaluates whether the combined application of phosphorus fertilizer and an ash-carbon amendment from industrial by-products can improve soil fertility and barley yield. In a three-year field experiment [...] Read more.

Phosphorus deficiency and declining organic matter limit crop productivity in Northern Kazakhstan’s chernozem soils. This study evaluates whether the combined application of phosphorus fertilizer and an ash-carbon amendment from industrial by-products can improve soil fertility and barley yield. In a three-year field experiment (2018–2020), four P rates (1/10, 1/5, 1/2, and the full recommended dose, Prec) were tested with 100 kg ha⁻¹ of ash–carbon product (“Agrobionov”). Across growth stages, we measured cellulolytic microbial activity, water-stable soil aggregates (%WSA), and grain yield. Relative to the control, P + ash–carbon increased microbial activity by up to 57.6% and %WSA by up to 76%. The highest yield (1.32 t ha⁻¹) occurred with Agrobionov + ½ Prec, a 51.7% increase over the control. These results indicate that pairing moderate P rates with an ash–carbon amendment enhances soil biological and physical properties and improves yield in P-deficient chernozems, supporting the sustainable use of industrial by-products as cost-effective soil amendments. Future work should assess long-term effects on C sequestration, nutrient cycling, and economic feasibility. Full article

(This article belongs to the Special Issue Integrated Soil Management: Food Supply, Environmental Impacts, and Socioeconomic Functions: 2nd Edition)

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15 pages, 1480 KB

Open AccessArticle

Turning Waste into Fertilizer: Aloe vera Leaf Shavings Improve Plant Growth and Support Soil Fertility in Organic Systems

by Isaiah E. Jaramillo, Carine Cocco, James Jihoon Kang, Chu-Lin Cheng and Engil Pereira

Soil Syst. 2025, 9(4), 113; https://doi.org/10.3390/soilsystems9040113 - 15 Oct 2025

Viewed by 521

Abstract

The Aloe vera industry discards large amounts of outer leaf tissue (“shavings”), creating an opportunity to repurpose this byproduct as a sustainable fertilizer. This study evaluated whether aloe shavings can serve as a plant-based alternative to compost in organic Aloe vera production. A [...] Read more.

The Aloe vera industry discards large amounts of outer leaf tissue (“shavings”), creating an opportunity to repurpose this byproduct as a sustainable fertilizer. This study evaluated whether aloe shavings can serve as a plant-based alternative to compost in organic Aloe vera production. A field trial in the Lower Rio Grande Valley of Texas tested three treatments: aloe shavings (applied to supply 39 kg N ha⁻¹), organic compost (39 kg N ha⁻¹), and a non-fertilized control. Laboratory incubations further assessed nitrogen mineralization and microbial respiration. Aloe shavings significantly enhanced vegetative growth: leaf number increased from 5.7 to 12.3 leaves per plant (+115% over the season), and leaf length rose from 20 to 32 cm, with the greatest gains in September and March (p < 0.05). At harvest, plants receiving aloe shavings produced 456 g total leaf weight and 151 g gel weight per plant, compared to 375 g and 108 g in the control. Incubations showed initial nitrogen immobilization (negative mineralization) but subsequent slow release, while microbial respiration was higher in compost (2.3 mg CO₂-C kg⁻¹ day⁻¹) than aloe shavings (1.4 mg CO₂-C kg⁻¹ day⁻¹). These results highlight aloe shavings as a low-cost, slow-release organic amendment that reduces waste, supports circular economy practices, and enhances Aloe vera growth without mineral nitrogen addition. Full article

(This article belongs to the Special Issue Soil Fertility Management, Mitigating GHG Emissions and Sustainable Agriculture: 2nd Edition)

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27 pages, 3476 KB

Open AccessArticle

Land Use Modifies the Inherent Effect of Soil Properties on Soil Bacterial Communities in Humid Tropical Watersheds

by Sunshine A. De Caires, Sabine Reinsch, Duraisamy Saravanakumar, Chaney St. Martin, Mark N. Wuddivira, Bernie J. Zebarth, Fuat Kaya, Mengying Liu, Durga P. M. Chinthalapudi, Shankar Ganapathi Shanmugam and Bobbi Helgason

Soil Syst. 2025, 9(4), 112; https://doi.org/10.3390/soilsystems9040112 - 15 Oct 2025

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Abstract

Soil bacterial communities are vital for ecosystem functioning in the humid tropics, yet their response to land-use change remains poorly understood. This knowledge gap is exacerbated by the lack of long-term studies. We employed a space-for-time substitution approach to assess the effects of [...] Read more.

Soil bacterial communities are vital for ecosystem functioning in the humid tropics, yet their response to land-use change remains poorly understood. This knowledge gap is exacerbated by the lack of long-term studies. We employed a space-for-time substitution approach to assess the effects of land-use intensification on soil bacterial communities across a gradient of anthropogenic disturbance in Trinidad. Three sub-watersheds (Arouca = pristine, Maracas = intermediate, Tacarigua = intensive) were selected, each containing adjacent forest, grassland, and agricultural land uses. We combined geophysical soil apparent electrical conductivity (ECa-directed) sampling with 16S rDNA gene amplicon sequencing to characterize bacterial communities and their relationships with soil and landscape properties. Soil properties were the primary determinant of bacterial community structure, explaining 56% of the variation (p < 0.001), with pH, clay content, hygroscopic water, and nutrient availability as key drivers. Bacterial α-diversity differed significantly among sub-watersheds (p < 0.01), with Tacarigua exhibiting lower richness and diversity compared to Arouca and Maracas, but not across land uses. While a core microbiome of ten bacterial families was ubiquitous across land uses, indicating a stable foundational community, land-use intensification significantly altered β-diversity (p < 0.01 among sub-watersheds). Agricultural soils showed the greatest divergence from forest soils (p < 0.05), with a marked decline in key Proteobacterial families (e.g., Xanthomonadaceae, Pseudomonadaceae) involved in nutrient cycling and plant growth promotion. Although inherent soil properties shape the core microbiome, land-use intensification acts as a strong secondary filter, shifting soil bacterial communities toward more stress-resistant Firmicutes with potentially less diverse functions. Our findings demonstrate the utility of integrating space-for-time substitution with molecular profiling to predict long-term microbial responses to environmental change in vulnerable tropical ecosystems. Full article

(This article belongs to the Special Issue Land Use and Management on Soil Properties and Processes: 2nd Edition)

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32 pages, 5461 KB

Open AccessArticle

Physical and Chemical Properties of Fire-Affected Soils from the Sagebrush Ecosystem of the Western US: A Laboratory Study

by Yasaman Raeofy, Vera Samburova, Markus Berli, Eden Furtak-Cole, Brad Sion, Sally Houseman, Kristine Lu, William Curtiss, Andrew J. Andrade, Bianca Martinez, Andrey Y. Khlystov and Hans Moosmüller

Soil Syst. 2025, 9(4), 111; https://doi.org/10.3390/soilsystems9040111 - 13 Oct 2025

Viewed by 435

Abstract

This study aims to understand the effects of wildfires in sagebrush ecosystem on soil properties by examining connections between Soil Water Repellency (SWR), reflectance, and chemistry. Ash and burned soil samples were collected after performing laboratory burns of three common sagebrush plants: sagebrush, [...] Read more.

This study aims to understand the effects of wildfires in sagebrush ecosystem on soil properties by examining connections between Soil Water Repellency (SWR), reflectance, and chemistry. Ash and burned soil samples were collected after performing laboratory burns of three common sagebrush plants: sagebrush, rabbitbrush, and bitterbrush. The collected samples were analyzed for their physical properties, including SWR measured by Water Drop Penetration Time (WDPT) and Apparent Contact Angle (ACA), and solar spectral reflectance in the wavelength range of 350 to 2500 nm. Chemical functional groups of the samples were analyzed using Fourier-Transform Infrared (FTIR) spectroscopy. WDPT and ACA values were in the range of 1 to 600 s and ~10° to 88°, respectively, for all three tested fuels. The FTIR analysis showed a decrease (~2 to 4 times) in the ratio of COO⁻/C=C signals for the burned soil samples compared to the unburned soil samples. Overall, increase in temperature and ACA levels for the samples of burned and burned soil from a 2 cm depth led to increased formation of non-polar compounds with C=C functional groups, and decarboxylation. Full article

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20 pages, 1116 KB

Open AccessArticle

Investigating the Effects of Soil Type and Potassium Fertiliser Timing on Potassium Leaching: A Five-Soil Lysimeter Study

by Thomas P. McCarthy, John B. Murphy and Patrick J. Forrestal

Soil Syst. 2025, 9(4), 110; https://doi.org/10.3390/soilsystems9040110 - 13 Oct 2025

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Abstract

Potassium (K) is essential for grassland productivity, but soil K leaching can reduce fertiliser use efficiency, increasing environmental losses. International evidence suggests soil type and K fertiliser timing influence K leaching, yet limited data exist for Ireland’s diverse soil types. This study investigated [...] Read more.

Potassium (K) is essential for grassland productivity, but soil K leaching can reduce fertiliser use efficiency, increasing environmental losses. International evidence suggests soil type and K fertiliser timing influence K leaching, yet limited data exist for Ireland’s diverse soil types. This study investigated the effects of K fertiliser timing (autumn, winter, and spring) and soil type on K leaching using a controlled lysimeter facility with five representative Irish soils sown with perennial ryegrass. Potassium fertiliser (125 kg K ha⁻¹) was applied in October, December, or February, with leachate collected from October to April. Soil type affected cumulative K leaching (1.4–9.8 kg ha⁻¹; p ≤ 0.001), with the greatest losses observed in sandy soils. Potassium and nitrogen uptake in spring-harvested grass were also influenced by soil type (p ≤ 0.05), with strong positive correlation between the two nutrients (R² = 0.78; p ≤ 0.001). Temporally, significant interactions (p ≤ 0.05) between K application timing and sampling date were found for K leachate in three of the five soils tested. Autumn and winter applications tended to increase cumulative leaching risk, especially on coarser-textured soils such as the Oakpark soil (p ≤ 0.05). The study indicates that applying K in early spring will tend to reduce leaching K losses, particularly on sandy soils. Full article

(This article belongs to the Topic Soil Health and Nutrient Management for Crop Productivity)

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22 pages, 2913 KB

Open AccessArticle

Spatial Variability and Temporal Changes of Soil Properties Assessed by Machine Learning in Córdoba, Argentina

by Mariano A. Córdoba, Susana B. Hang, Catalina Bozzer, Carolina Alvarez, Lautaro Faule, Esteban Kowaljow, María V. Vaieretti, Marcos D. Bongiovanni and Mónica G. Balzarini

Soil Syst. 2025, 9(4), 109; https://doi.org/10.3390/soilsystems9040109 - 10 Oct 2025

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Abstract

Understanding the temporal dynamics and spatial distribution of key soil properties is essential for sustainable land management and informed decision-making. This study assessed the spatial variability and decadal changes (2013–2023) of topsoil properties in Córdoba, central Argentina, using digital soil mapping (DSM) and [...] Read more.

Understanding the temporal dynamics and spatial distribution of key soil properties is essential for sustainable land management and informed decision-making. This study assessed the spatial variability and decadal changes (2013–2023) of topsoil properties in Córdoba, central Argentina, using digital soil mapping (DSM) and machine learning (ML) algorithms. Three ML methods—Quantile Regression Forest (QRF), Cubist, and Support Vector Machine (SVM)—were compared to predict soil organic matter (SOM), extractable phosphorus (P), and pH at 0–20 cm depth, based on environmental covariates related to site climate, vegetation, and topography. QRF consistently outperformed the other models in prediction accuracy and uncertainty, confirming its suitability for DSM in heterogeneous landscapes. Prediction uncertainty was higher in marginal mountainous areas than in intensively managed plains. Over ten years, SOM, P, and pH exhibited changes across land-use classes (cropland, pasture, and forest). Extractable P declined by 15–35%, with the sharpest reduction in croplands (−35.4%). SOM decreased in croplands (−6.7%) and pastures (−3.1%) but remained stable in forests. pH trends varied, with slight decreases in croplands and forests and a small increase in pastures. By integrating high-resolution mapping and temporal assessment, this study advances DSM applications and supports regional soil monitoring and sustainable land-use planning. Full article

(This article belongs to the Special Issue Use of Modern Statistical Methods in Soil Science)

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22 pages, 2017 KB

Open AccessReview

A New Era in the Discovery of Biological Control Bacteria: Omics-Driven Bioprospecting

by Valeria Valenzuela Ruiz, Errikka Patricia Cervantes Enriquez, María Fernanda Vázquez Ramírez, María de los Ángeles Bivian Hernández, Marcela Cárdenas-Manríquez, Fannie Isela Parra Cota and Sergio de los Santos Villalobos

Soil Syst. 2025, 9(4), 108; https://doi.org/10.3390/soilsystems9040108 - 10 Oct 2025

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Abstract

Biological control with beneficial bacteria offers a sustainable alternative to synthetic agrochemicals for managing plant pathogens and enhancing plant health. However, bacterial biocontrol agents (BCAs) remain underexploited due to regulatory hurdles (such as complex registration timelines and extensive dossier requirements) and limited strain [...] Read more.

Biological control with beneficial bacteria offers a sustainable alternative to synthetic agrochemicals for managing plant pathogens and enhancing plant health. However, bacterial biocontrol agents (BCAs) remain underexploited due to regulatory hurdles (such as complex registration timelines and extensive dossier requirements) and limited strain characterization. Recent advances in omics technologies (genomics, transcriptomics, proteomics, and metabolomics) have strengthened the bioprospecting pipeline by uncovering key microbial traits involved in biocontrol. Genomics enables the identification of biosynthetic gene clusters, antimicrobial pathways, and accurate taxonomy, while comparative genomics reveals genes relevant to plant–microbe interactions. Metagenomics uncovers unculturable microbes and their functional roles, especially in the rhizosphere and extreme environments. Transcriptomics (e.g., RNA-Seq) sheds light on gene regulation during plant-pathogen-bacteria interactions, revealing stress-related and biocontrol pathways. Metabolomics, using tools like Liquid Chromatography–Mass Spectrometry (LC-MS) and Nuclear Magnetic Resonance spectroscopy (NMR), identifies bioactive compounds such as lipopeptides, Volatile Organic Compounds (VOCs), and polyketides. Co-culture experiments and synthetic microbial communities (SynComs) have shown enhanced biocontrol through metabolic synergy. This review highlights how integrating omics tools accelerates the discovery and functional validation of new BCAs. Such strategies support the development of effective microbial products, promoting sustainable agriculture by improving crop resilience, reducing chemical inputs, and enhancing soil health. Looking ahead, the successful application of omics-driven bioprospection of BCAs will require addressing challenges of large-scale production, regulatory harmonization, and their integration into real-world agricultural systems to ensure reliable, sustainable solutions. Full article

(This article belongs to the Special Issue Research on Soil Management and Conservation: 2nd Edition)

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18 pages, 1469 KB

Open AccessArticle

Olive Pomace-Derived Compost: Phytotoxicity Assessment and Relevance for Soil Systems

by Qaiser Javed, Mohammed Bouhadi, Igor Palčić, Dominik Anđelini, Danko Cvitan, Nikola Major, Marina Lukić, Smiljana Goreta Ban, Dean Ban, David Heath, Tomaž Rijavec, Aleš Lapanje and Marko Černe

Soil Syst. 2025, 9(4), 107; https://doi.org/10.3390/soilsystems9040107 - 30 Sep 2025

Viewed by 923

Abstract

Olive pomace (OP) contains phytotoxic compounds that can impair plant growth and soil quality. Composting provides an effective method for detoxifying olive pomace (OP) and improving its suitability for agricultural use. Therefore, this study investigated the phytotoxic effects of raw olive pomace filtrate [...] Read more.

Olive pomace (OP) contains phytotoxic compounds that can impair plant growth and soil quality. Composting provides an effective method for detoxifying olive pomace (OP) and improving its suitability for agricultural use. Therefore, this study investigated the phytotoxic effects of raw olive pomace filtrate (OPF) on seed germination in radish (Raphanus sativus L.) and barley (Hordeum vulgare L.), as well as the impact of composted olive pomace (COP) on their growth. Seeds were exposed to OPF at concentrations of 0% (control), 1%, 3%, 5%, 10%, 20%, and 100%. Additionally, three composting treatments were evaluated: R1 (control: OP + barley straw), R2 (OP + barley straw + urea), and R3 (OP + barley straw + sheep litter). Results showed that OPF at concentrations of 10%, 20%, and 100% significantly reduced seed germination, with complete inhibition at concentrations > 10%. The COP treatments showed different physicochemical properties, such as R2 exhibiting better nutrient availability (C/N = 19, oil content = 0.04%). R3 had the highest concentrations of K (40,430.2 mg/kg) and P (6022.68 mg/kg). Results also indicated that R1 significantly reduced radish dry biomass production compared to barley, although R2 performed slightly better than R1 and R3. The findings highlight the need for proper compost stabilization to minimize the phytotoxicity and improve the agricultural potential of COP for improving soil health. Full article

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Open AccessArticle

Arsenic Behavior in Paddy Soils: Sorption Capacity and the Role of Algal Addition

by Diego Arán, Maria Manuela Abreu, Luisa Louro Martins, Miguel Pedro Mourato and Erika S. Santos

Soil Syst. 2025, 9(4), 106; https://doi.org/10.3390/soilsystems9040106 - 25 Sep 2025

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Abstract

Rice is one of the world’s most consumed foods, and the cereal that most efficiently uptakes and accumulates As, contributing to human health risk. Flooded rice fields alter Eh-pH conditions and, consequently, the proportion of As(III)/As(V), favoring their accumulation in the crop. The [...] Read more.

Rice is one of the world’s most consumed foods, and the cereal that most efficiently uptakes and accumulates As, contributing to human health risk. Flooded rice fields alter Eh-pH conditions and, consequently, the proportion of As(III)/As(V), favoring their accumulation in the crop. The use of algae in paddy soils can improve fertility and C-stock and affect chemical conditions and As availability. This study aimed to evaluate the effect of algae application on: As adsorption capacity in paddy soils from Sado, Portugal, changes in pH-Eh conditions in the soil–water environment, and consequent As speciation. Batch-based As adsorption assays were performed with different solid–solution ratios and Chlorella minutissima algae application, and fitted to the Freundlich and Langmuir linear models. In semi-continuous column assays, simulating rice field conditions, the effect of algae on the pH-Eh of soil pore water was evaluated. The soil quality assessment showed pseudo-total contents of As and other elements higher than Portuguese agriculture limits (11 mg As kg⁻¹), but their availability was low, posing no environmental risk. The studied soils had great As adsorption, which increased with algae application (1.07 mg g⁻¹). Algae application favored oxygenation, increasing Eh values, and maintaining As(V) species. This indicated a potential approach to reducing As(III) mobility. Full article

(This article belongs to the Special Issue Adsorption Processes in Soils and Sediments)

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Soil Syst., Volume 9, Issue 4 (December 2025) – 16 articles

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