Southeastern Australia encompasses temperate to semi-arid climatic zones and supports agricultural and pastoral systems. Periodic droughts have imposed substantial financial, social, and psychological burdens on farming communities, highlighting the need for improved drought and agricultural risk management. These impacts underscore the importance of soil moisture, a key variable for monitoring, hydrologic and climate modelling, and seasonal forecasting. However, obtaining soil moisture observations across depths with sufficient spatial and temporal resolution remains challenging. Current information sources, including in-situ monitoring networks, satellite remote sensing products, and land surface model outputs, provide unique advantages but are constrained by uncertainties and limitations. In-situ networks provide valuable depth-specific measurements at targeted sites, supporting agricultural decision-making and calibration and validation of remote sensing and model-based products. Despite their importance, a systematic synthesis and assessment of soil moisture monitoring networks in southeastern Australia is lacking. This knowledge gap limits researchers, practitioners, and policymakers seeking to understand network characteristics, data availability, and opportunities for improved data integration. This review addresses this gap by documenting and summarising key in-situ soil moisture monitoring networks relevant to southeastern Australia and highlighting their complementary value for data applications. The review identifies key challenges, including differences in measurement protocols, calibration approaches, spatial representativeness, data accessibility, and long-term operational sustainability. It also discusses future priorities for improved network design, standardisation, and integration with satellite and modelling products. Overall, this paper highlights the potential of coordinated monitoring and data integration to maximise in-situ soil moisture observations, supporting agricultural, hydrological, and climate-resilience applications in southeastern Australia.
In semi-arid pastureland, where plant cover, root biomass, and soil aggregation are especially vulnerable to disturbance, grazing pressure is a key factor influencing the dynamics of soil organic carbon (SOC). To clarify the mechanisms of C stabilization under low grazing pressure (LGP), moderate grazing pressure (MGP), high grazing pressure (HGP), this study combined aggregate size fractionation with δ13C isotopic analysis and compared to ungrazed control (UGC). The mass of large macroaggregates were significantly higher (32–65%) under LGP and MGP than HGP. The carbon (C) concentrations within aggregates were significantly higher under MGP. The particulate organic matter associated C was also significantly higher under LGP and MGP (16–33%) than HGP. The POM had lower δ13C than aggregates suggesting that LGP and MGP supported aggregate stability and SOC retention by enhancing macroaggregate formation and promoting the occlusion of POM into microaggregates, thereby fostering mineral-associated organic carbon (MOM) stabilization. The evidence that severe grazing can deplete SOC reserves, on the other hand, is supported by disruption of large macroaggregate stability and reduction of large macroaggregate-protected C. The root-, faeces-, and urine-originated C contributed for ~9.5–44, 4.75–39, and 4–35% of total C within aggregates. With δ13C enrichment in macroaggregates, LGP and MGP retained greater SOC reserves. Overall, the findings suggest that in semi-arid environments, low and medium grazing intensities could enhance soil carbon sequestration capacity enhancing soil structural stability and better occlusion of root derived C in presence of POM. Hence, low to moderate grazing pressure can be advocated for sustaining carbon sequestration without harming soil structural stability in semi-arid pastureland.
Soil organic carbon (SOC) in wetlands is crucial in global carbon cycle due to vast carbon storage in marshes. In addition to broader environmental factors SOC thermal stability is strongly influenced by its molecular composition and iron-mediated mineral protection. However, effects of the interaction between molecular composition and iron-mediated mineral protection on SOC thermal stability are still not completely understood across soil profiles. Here pyrolysis-chromatography/mass spectrometry, iron-associated organic carbon fraction (OC-Fe) analysis, and thermal analysis were combined to investigate depth-dependent controls on SOC thermal stability in seasonally frozen marshes from the Greater Khingan region, Northeast China. Results revealed that topsoil (0-30 cm) exhibited significantly lower thermal stability than subsoil (30-50 cm), characterized by lower TG-T50(340.89 °C vs. 353.90 °C) and DSC-T50(365.86 °C vs. 375.86 °C), despite a significantly higher SOC content observed in topsoil(24.84%vs.6.61%).The relative abundances of pyrolytic Lignin (Lg), Polycyclic Aromatic Hydrocarbons (PAHs) and Nitrogen-containing compounds (Nc) were significantly higher in the topsoil (2.09%, 5.04% and 5.96%) than in the subsoil (1.42%, 4.20% and 4.87%). The median of OC-Fe content and fOC−Fe showed no significant differences between the topsoil and the subsoil. Variation partitioning and robust regression analyses indicated that SOC thermal stability in the topsoil was strongly associated with coupled interactions between molecular composition and iron-mediated mineral protection. In contrast, SOC thermal stability in the subsoil was more closely related to the selective preservation of chemically processed organic matter and weaker mineral-molecular interaction effects. These findings reveal depth-dependent differences in SOC thermal stability and highlight the importance of coupled molecular composition and iron-mediated mineral protection controls on SOC thermal stability in cold-region marsh soils.
This study focuses on the Caatinga, the largest seasonally dry tropical forest in South America. Climate, low primary productivity, and severe erosion result in soils with low organic carbon content. Inselbergs stand out due to their unique biodiversity and serve as bioclimatic indicators for studies on the origin of organic compounds. Soil and litter samples were collected from three inselbergs at different slope positions. Morphological, physical, and chemical properties were determined. Data revealed a variation in SOC content ranging from 1.5% to 12.8% among the three inselbergs, with the highest contents predominantly at the backslope position. SOC content showed significant correlations with clay, available water, Ca2+, and Mg2+, and a weak correlation with phosphorus. Principal Component Analysis explained 62.1% of the total variance. PC1 represented a soil fertility gradient, while PC2 was primarily associated with SOC content and cation exchange capacity. Linear mixed-effects models revealed significant effects of both slope position and site on the multivariate gradients, with the highest scores occurring at the backslope rather than following a monotonic trend along the slopes. The δ13C values indicated a predominantly C₃-derived organic matter source, with spatial differences in vegetation-derived carbon inputs associated with local microtopographic conditions. The accumulation of fine sediments, litter, and organic matter in depositional microsites may promote soil development, moisture retention, and nutrient enrichment, favoring vegetation establishment. Therefore, inselberg soils contribute to maintaining Caatinga biodiversity and carbon stocks.
Agriculture faces the dual challenge of sustaining productivity while mitigating climate change. This critical narrative review synthesizes evidence from open-field studies on crop rotation, organic amendments, and conservation tillage, examining their collective influence on soil carbon and nitrogen dynamics. These practices generally enhance soil organic carbon (SOC) and total nitrogen (STN), while effects on soil inorganic carbon (SIC) remain less consistent and often depth-dependent. Crop rotation improves SOC and STN stocks, particularly in corn-soybean systems, whereas organic amendments such as compost, biochar, and manure increase SOC but show variable impacts on SIC. Conservation tillage, especially no-till, promotes SOC accumulation but requires careful consideration of sampling depth to avoid misinterpretation of carbon balances. Combined management practices often yield synergistic benefits for SOC and STN, though greenhouse gas (GHG) emissions remain mixed and context-specific. This review highlights critical knowledge gaps, including limited field-based data on SIC dynamics and geographic bias toward temperate regions, underscoring the need for broader, long-term studies. Addressing these gaps is essential for advancing climate change mitigation and achieving sustainable development goals.
Topographic variation strongly influences soil development, fertility, and sustainable land management in the Ethiopian highlands. This study characterized the morphological, physical, and chemical properties of soils along an upper-middle-lower slope toposequence in the Akuma Watershed, southwestern Ethiopia. The results demonstrated clear topographic effects on soil development and fertility. Upper slope soils were clayey, well-drained, and strongly acidic (pH 4.76–4.83), with higher exchangeable acidity and lower concentrations of exchangeable base cations. Middle slope soils exhibited intermediate physical and chemical characteristics, reflecting transitional pedogenic conditions. Lower slope soils showed greater accumulation of organic carbon, exchangeable Ca and Mg, and relatively higher pH values (5.20–5.60), indicating the depositional enrichment of nutrients and finer materials. Bulk density generally increased and total porosity decreased with depth across all profiles. According to WRB, the soils were classified as Dystric Acrisol on the upper slope, Dystric Nitisol on the middle slope, and Dystric Fluvisol on the lower slope, reflecting contrasting pedogenic processes associated with landscape position. The observed acidity gradient from upper to lower slopes confirms that topography governs nutrient redistribution, soil development, and fertility status within the watershed. These findings provide baseline information for site-specific soil management and indicate that liming and erosion control should be prioritized on upper slopes, integrated nutrient management on middle slopes, and conservation of organic matter and balanced fertilization on lower slopes to improve agricultural productivity and sustain soil resources.
Evaluating soil quality based solely on official, relatively high action (or intervention) levels of potentially toxic elements (PTEs) can overlook moderate contamination. Therefore, establishing ambient geochemical background, using the data from local topsoil monitoring provides a more reliable tool for soil health evaluation. This is especially true when overall thresholds are further differentiated into factor-specific or territory-related (local/regional) baselines. This study aims to derive country-wide baseline values for major PTEs using national monitoring of cropland topsoil chemistry from 216 permanent plots operating since 1980. To minimize discrepancies between mean and median values, an outlier elimination by iterative 2σ technique was applied. The resulting baseline values (Hg: 0.025, Cd: 0.13, As: 2.2, Co: 2.4, Ni: 4.0, Cu: 4.6, Sr: 5.6, Cr: 7.8, Pb: 12, Zn: 25, Ba: 35 and Mn: 275 mg kg−1), calculated from the refined national soil monitoring data, are comparable to the median values reported for Polish territory by pan-European inventories like GEMAS and LUCAS. Minor exceptions, particularly for Hg, stem primarily from methodological differences. This refined national dataset enables the further differentiation of baseline values across, in particular, classes of soil texture, parent material, and dominant Reference Soil Groups according to the World Reference Base classification. Furthermore, notable spatial variation in mean PTE concentrations allows for regional baseline specifications across Polish latitudinal geo-zones (young glacial landscapes, the European sand belt, the European loess belt, and mountain zones), clusters of European soil regions and clusters of administrative units (EU NUTS 2 regions), aligning with recommendations from the European Directive for soil health evaluation and soil monitoring. Ultimately, a consistency between national soil monitoring and pan-European inventory datasets was confirmed, underscoring their potential for deriving local PTE baselines for reliable soil health assessment that accounts for local and regional environmental conditions.
Legacy soil maps remain essential for national land-use planning. However, their thematic accuracy and spatial resolution are often insufficient for contemporary applications requiring reliable estimates. This study presents a digital soil-mapping approach to update legacy soil information without extensive field sampling, demonstrated for arable lands in the Republic of Tatarstan (4.5 million ha). The proposed approach integrates the 1:2.5 M Soil Map of Russia with multisource predictors derived from principal component analysis of MODIS time-series imagery (2013–2025). These predictors represent landscape invariants associated with stable productivity, thermal, and moisture regimes, complemented by topographic, climatic, and parent material covariates. Principal component analysis was applied to extract stationary environmental regimes, while linear discriminant analysis was used to identify stable boundaries between soil-forming conditions within this invariant space. Linear discriminant analysis produced a refined predictive soil map (250-m resolution) with four units corresponding to Russian soil types and World Reference Base classes: Albic Retisols, Albic Luvisols/Greyic Phaeozems, Chernozems, and Fluvisols. Validation against 166 independent soil profile observations yielded an overall accuracy of 59.6% and a Kappa coefficient of 0.4, indicating moderate agreement beyond chance. Unit-specific accuracies ranged from 75.0% (Albic Retisols) to 50.6% (Albic Luvisols/Greyic Phaeozems). The lowest performance for Albic Luvisols/Greyic Phaeozems reflects their transitional characteristics in the forest–steppe ecotone. Probability maps showed spatial variation in confidence for soil-unit assignments. Unlike purely predictive machine-learning approaches, this framework emphasizes the identification of stable relationships between environmental regimes and soil units rather than maximizing classification accuracy alone.
The formation and accumulation of secondary carbonates represent an important pathway for long-term carbon sequestration in global dryland regions. However, accurately assessing their contribution to the regional carbon budget requires distinguishing between pedogenic (in-situ soil formation) and sedimentary processes, which often occur concurrently in dynamic environments. This study investigated the formation and accumulation of carbonate features within four pedosedimentary sections located along ephemeral stream banks in semi-arid central Botswana. The method used involved combining morphological and physicochemical characterisation with geochemical indices in the observed horizons/layers. Geochemical indices include the robust chemical weathering index (RW), the calcification index ((Mg + Ca)/Al), the clayeyness index (Al/Si) and Mg/Ca ratios. Analysis of the sections reveals a cyclical palaeoenvironmental history marked by palaeosols whose development was repeatedly interrupted by successive episodes of fluvial sedimentary deposition, followed by the resumption of modern pedogenesis. Particle size analysis of the deposit layers confirms a pulsed fluvial regime, with sediments ranging from poorly sorted fine sand upstream to extremely poorly sorted coarse silt downstream, indicating hydraulic sorting according controlled by flood energy. Geochemically, the low RW values, ranging overall between 30% and 60%, and the clay index generally below 0.3 indicate a limited degree of chemical weathering and low clay neoformation, reflecting the predominance influence of the arid environment. Calcification was identified as the dominant pedogenic process in all sections (both ancient and modern), characterised by a high CaCO3 content (14 to 22%), confirmed by the calcification index in the calcic horizons. The low Mg/Ca ratio strongly suggests the predominance of calcite as the main secondary carbonate phase also confirmed by XRD evidence. These findings highlight that the total carbonate accumulation in the study area is a direct result of the complex interplay between repetitive fluvial deposition (pedosedimentary history) and subsequent in-situ pedogenic calcification. The results underscore the critical importance of secondary carbonate accumulation in the soils of Botswana and highlight a complex paleoenvironmental evolution.
This research explores long-term changes in soil temperature and moisture in Europe, using monthly data from meteorological stations between 1990 and 2024. The analysis was conducted at four soil depths (10, 40, 100, and 200 cm) using decadal change assessment methods: the Mann-Kendall trend test, and Emerging Hotspot Analysis (EHA). The results indicated that as depth increases, the proportion of areas with statistically significant trends also increases (temperature: from 46% to 86% and moisture: from 20% to 60%), accompanied by changes in the nature and concentration of hot and cold spots. The surface layers are more affected by short-term fluctuations, while greater depths exhibit a consistent trend of warming and moistening. Northern and Western Europe experience decreases in moisture and temperature, while Eastern and Southeastern Europe experience increases. These dynamic trends in depth gradients and spatial contrasts reflect a combination of climatic, geological, and anthropogenic factors. These findings can play a key role in improving climate models, climate change adaptation planning, and water resource management at the regional and local levels.
Fragipanic (FR) soils are widely distributed, occurring on practically all continents. In southern Brazil, these soils are rarely detected, although several environmental characteristics are considered favorable for their formation. We evaluated four soil profiles in the Porto Alegre Metropolitan Region that exhibit a cohesive character, expressed by a firm or very firm moist consistence, and are slightly sticky and slightly plastic when wet. Field characteristics allowed the separation of two profiles with FR features, profiles 3 and 4 (P3 and P4), and two non-fragipanic (NF) profiles, P1 and P2. Samples were collected for physical, chemical, elemental, and mineralogical analyses, in addition to undisturbed samples for thin-section analysis. These soils exhibit a textural gradient or an abrupt textural change, with a tendency toward higher base saturation and lower aluminum saturation in the subsurface, denoting the influence of ferrolysis. Gleyzation and lessivage were observed, evidenced by Fe-depletion zones, nodules, coatings, and infillings in the subsurface horizons. Short-range-order minerals appear to have a similar contribution to the clay fraction of both the NF and FR profiles, but the lower clay content in the FR profiles results in these minerals acting as “binding points”, linking coarser grains. This is reinforced by thin-section analysis, which showed the occurrence of an undifferentiated b-fabric, higher c/f ratios, and opaline infillings and coatings in P3 and P4. Wetting and drying cycles, typical of the local climate, favor the consolidation of this material. The associated occurrence of these features and characteristics, detected through physical, chemical, and micromorphological analyses, appears to be responsible for fragipan development.
Soil is crucial for providing multiple ecosystem services, playing a key role in environmental sustainability and climate change mitigation. Therefore, this study aimed to propose an index of soil-related ecosystem services (SES) across different land-uses within the main soil orders of the Brazilian Atlantic Forest biome. The study assessed the ecosystem services provided by two soil orders (Ultisols and Oxisols) under six different land-uses (forest fragment, forest restoration, pasture, sugarcane, cassava, and annual crop) in the Pontal do Paranapanema region, Brazil. The proposed SES index integrates indicators of carbon sequestration, carbon cycling, soil fertility, and soil structure and water regulation. The results showed that the forest fragment and forest restoration had the highest values for the SES index, with ES1 = 0.84 and 0.75, ES2 = 0.79 and 0.69, ES3 = 0.57 and 0.59, and ES4 = 0.88 and 0.83, respectively, while cassava had the lowest performance, with ES1 = 0.48, ES2 = 0.47, ES3 = 0.45, and ES4 = 0.74, mainly due to degraded soil structure and reduced carbon sequestration. Synergies predominated across all land-uses, except in forest fragments, where a single functional conflict was observed. The strongest synergies were associated with interactions between carbon-related processes and soil structure and water regulation. The proposed SES index represents a practical tool to support sustainable soil management and land-use decisions in tropical regions such as the Atlantic Forest biome.
Land-use change, topography, and soil depth are key controls of soil quality and soil organic carbon (SOC) dynamics in semi-arid agroecosystems, yet their combined effects remain insufficiently quantified in the Northwestern Lowlands of Ethiopia. This study integrated soil physicochemical analyses, principal component analysis (PCA), and a Soil Quality Index (SQI) approach to evaluate spatial and vertical variability in soil properties across contrasting land-use systems and slope positions. Soil samples were collected from replicated plots representing different land-use types and topographic positions to ensure representative spatial coverage. Results indicated that land use and topography significantly influenced SOC, soil physical properties, and nutrient status (p < 0.05). Forest and grassland soils exhibited higher SOC stocks and SQI values than cultivated and bare lands, reflecting lower disturbance intensity and greater organic matter inputs. SOC and SQI consistently decreased along slope gradients, indicating erosion-driven redistribution and reduced organic carbon inputs in downslope and degraded positions. PCA identified soil organic matter, structural properties, and nutrient availability as the main drivers of soil variability, explaining 78.3% of the total variance. The close agreement between PCA-derived indicators and SQI patterns highlights the robustness of multivariate approaches for soil quality assessment. Overall, land-use change emerged as the primary driver of soil quality variation, while topographic position modulated SOC redistribution and nutrient dynamics. These findings indicate that intensified cultivation in dryland systems accelerates SOC depletion and soil functional decline, increasing vulnerability to climatic variability and environmental stresses. The PCA-based SQI framework provides a practical tool for soil quality assessment and supports targeted land management and restoration strategies in semi-arid landscapes.
This study was conducted in 89 vineyard soil profiles within the Valdepeñas Protected Designation of Origin (Castilla-La Mancha, Spain), where viticulture is a key agricultural activity. In this region, as in many others, compacted soils may not promote adequate root development, as they increase penetration resistance and reduce porosity. These conditions restrict the growth and development of the plant and, consequently, affect vineyard productivity and profitability. Therefore, it is essential to identify and analyse soil compaction in vineyard soils. The objectives of this study were to assess the degree of soil compaction in the surface horizons of vineyard soils within the Valdepeñas Protected Designation of Origin (PDO) using packing density (PD) as the main indicator, to classify soils according to established packing density thresholds and to analyse the influence of key soil physicochemical properties (particularly, texture, organic matter and calcium carbonate content) on soil compaction levels.The results show that 15.75% of the soils are classified as compacted (PD > 1.75 g/cm3), whereas soils with moderate compaction (and therefore at risk of future compaction) represent 64.03% of the studied soils (PD values between 1.40 and 1.75 g/cm3). Among the properties of the sampled soils, the influence of calcium carbonate content stands out, showing a weak but significant relationship with packing density (r = −0.24) and appearing to be an influential factor in the compaction of calcareous soils. These findings highlight the need for sustainable soil management practices to improve soil structural strength by increasing its resilience to compaction and vineyard productivity and underscore the importance of recognizing and protecting local terroirs.
Organic soils and soils rich in organic matter are important carbon sinks. However, many of them are used for agricultural purposes and therefore subjected to management impacts. Organic soils can develop under different environmental conditions and thus present distinctly different properties. Their mechanics and impacting factors are still quite unexplored. Consequently, this study aimed at evaluating the relationship between chemical properties of a broad range of organic soils and their microstructural stability and resistance under oscillatory shear as derived with rheometry. The study was carried out with soils rich in organic matter developed under different environmental conditions and in different regions of Brazil, comprising 37 organic horizons from 8 soil profiles under different land uses and vegetation cover. We found the pedogenetic environment to be the main impact due to its lasting and deterministic influence on the investigated soils, overriding even effects of the matric potential in some soils. We distinguish ponded and free-draining conditions: In soils with H horizons, i.e. formed under ponding water environment and located on concave landscape (PW-Hhoriz) in Espírito Santo, which are highly organic and poorly drained, the transition from saturated to −10 kPa resulted in a strong increase in resistance and viscoelasticity (Iz), with one Sapric Histosol being associated with higher bulk density (BD) and τmax, while another Sapric Histosol, with more carbon, was linked to soil organic carbon (SOC), soil gravimetric water content (θg), and pH. These results illustrate the dual role of organic carbon: under saturation, excess water reduces effective stress and promotes a lubricating effect, leading to low shear stresses; after drainage, the same carbon, together with cations, contributes to a stiffer microstructure. However, τmax and τLVR the profiles PW-Hhoriz under saturation were relatively low compared to the drained condition and to several profiles from Minas Gerais. In soils with O horizons, formed in a free-drainage environment and located on high altitude mountains under cold and humid climate (FD-Ohoriz) in Minas Gerais, the soil classes Cambisols, Ferralsols, and Histosols exhibited a rather similar behavior between 0 and − 10 kPa, indicating that SOC and base cations content is more determinant than matric potential itself in the hierarchy of controlling factors. However, drainage from 0 to −10 kPa systematically increased stiffness and microstructural stability due to the intensification of capillary forces and particle rearrangement, while the range of elastic deformations (γLVR) was less sensitive to matric potential. Our findings provide a basis for soil conservation decisions to take into account soil pedogenesis and prioritize practices that enhance microstructural stability according to the soil's specific pedogenetic conditions and inherent physical, chemical and hydro-mechanical properties.
Balancing soil health improvement with high crop productivity is a critical challenge for intensive agricultural systems. While cover cropping in no-till systems is well studied, the short-term impacts of corn (Zea mays L.)-wheat (Triticum aestivum L.)-soybean (Glycine max L.) rotations, with and without cereal rye (Secale cereale L.), on Alfisols with fragic properties remain less understood.A field experiment in Carbondale, Illinois, evaluated four treatments: corn-soybean with no cover crop (CNSN), corn-wheat-soybean without cereal rye (CWSN), corn-cereal rye-soybean-cereal rye (CRSR), and corn-wheat-soybean with cereal rye (CWSR). Because the trial captured the initial stages of rotation establishment, results emphasize short-term responses. Treatments CRSR, CWSR, and CWSN increased medium-sized aggregates (0.5–2 mm) compared with CNSN. Aggregate stability improved most under CWSR, with fewer unstable aggregates in the 0.25–2 and 2–4.75 mm size fractions. Bulk density was lower in CWSN than in CRSR and CWSR, whereas CRSR and CWSR maintained higher summer volumetric water content. Soil penetration resistance, saturated hydraulic conductivity, and organic matter with depth were similar among treatments. However, CRSR, CWSN, and CWSR had higher organic matter in the 0.053–0.25 and 2–4.75 mm size fractions compared to CNSN. Corn yield was reduced more in CRSR and CWSR (10.81 and 10.65 Mg ha−1) than in CWSN (11.94 Mg ha−1), whereas soybean yield was higher in CNSN and CRSR (3.53 and 3.57 Mg ha−1) compared to CWSN and CWSR (3.24 and 2.95 Mg ha−1). Wheat yield was similar between CWSN and CWSR. Results indicated that CWSR improved soil aggregation, water content, and organic matter while maintaining system productivity, offering a sustainable management strategy for fragic Alfisols.
Successional agroforestry systems are agroecological land-use strategies designed to incorporate ecological processes observed during natural ecosystem development. This study examined how agroforestry succession influences soil organic matter (SOM) chemistry and soil carbon stability in southern Brazil. Soil and litter samples were collected under five land-use conditions: a control area without agroforestry management; agroforestry systems with 1, 3, and 7 years of establishment; and a naturally regenerating forest with approximately 30 years of succession. The chemical composition of SOM was characterized using Fourier-transform infrared (FTIR) spectroscopy, while soil carbon stability was assessed through biodegradability assays. Along the successional gradient, soil carbon exhibited progressively greater stability, accompanied by an increased relative contribution of aliphatic functional groups and a higher abundance of nitrogen-containing compounds in SOM. These results indicate that agroforestry succession promotes molecular-level transformations in SOM that enhance carbon stabilization, likely reflecting combined effects of molecular composition, organo-mineral interactions, and physical protection mechanisms in soil, highlighting the role of agroecological management in driving soil carbon persistence through changes in organic matter chemistry.
Understanding the chemical and biological processes in the corn rhizosphere that govern nitrogen (N) availability can improve fertilizer management strategies, such as pig slurry (PS) application, in no-till systems on subtropical soils. This study aimed to assess changes in soil chemical properties and microbial activity associated with N availability in the rhizosphere of corn grown in an area with a 17-year history of PS and mineral fertilizer (MF) use. The study was conducted in a long-term field experiment (2004-2021) in southern Brazil, with treatments consisting of PS, MF, and a no-fertilizer control. Rhizospheric and non-rhizospheric (bulk) soils were sampled during the 2019/20 and 2020/21 growing seasons. Soil samples were analyzed for urease and (3-glucosidase activities, microbial biomass carbon (C) and nitrogen (N), total organic carbon (TOC), total N (TN), and pH. Long-term PS application enhanced N availability and improved soil quality in the rhizosphere compared with MF alone. PS increased TOC and enzyme activity, particularly (3-glucosidase activity in rhizospheric soil, which may facilitate N release to plants. These improvements were associated with increased crop yiels, despite rhizospheric soil pH remaining similar to that of the control treatment. PS also elevated microbial biomass C and N and urease activity, especially in the rhizosphere, although these responses were not directly associated with higher yields. Nevertheless, enhanced N availability in the rhizosphere was evident. These findings suggest that PS application may be a viable strategy for improving soil microbial activity and nutrient cycling in corn production systems under long-term no-till management.
Soil inorganic carbon (SIC) is the main form of soil carbon in drylands and is susceptible to land use changes. However, a comprehensive study on the SIC dynamic after afforestation is still lacking. In this study, we collected 883 data from 57 published papers to investigate the effects of afforestation on SIC, and then used a random forest model to spatially estimate SIC dynamic following afforestation. The results showed that the SIC content significantly rose by 14.21% after afforestation. The SIC accumulation magnitude after cropland afforestation was less than that after grassland and sandland afforestation. Mean annual precipitation was the primary factor affecting the changes in SIC after cropland afforestation, and soil pH was key effect factor to SIC variations after grassland and sandland afforestation. The SIC variations following afforestation were directly or indirectly affected by climate factors, soil pH, total nitrogen, cation exchange capacity and response ratio of soil organic carbon (RR-SOC), indicating that pedogenic inorganic carbon is a key factor in SIC accumulation after afforestation. Spatial predictions of SIC dynamics following afforestation showed that SIC accumulation rate is comparable to that of SOC, indicating that SIC is equally important in soil carbon sequestration. In conclusion, our research results emphasized the significance of SIC, ignoring SIC could lead to a significant underestimation of the carbon sequestration capacity of the afforestation areas.
Grasslands are known to be beneficial for increasing carbon stocks in soils as well as enhancing a range of essential soil ecosystem functions. Conversion of grassland to cropland can lead to loss of these benefits. The purpose of this study was to consider how the soil properties are altered after such land-use change in the boreal climate. Our study setup consisted of three fields which had been under extensive grassland management from 10 to over 30 years. Part of each field was ploughed and taken to cereal production and the rest was left as grassland. Carbon dioxide (CO2) fluxes from soil were measured during two growing seasons, and after the two years, the soil carbon stock, structure, and nematode densities were determined from both ploughed and undisturbed soils. Our results showed a practically and statistically significant land use change-induced reduction in soil carbon stock after two years. A significant reduction in the particulate organic carbon fraction was detected after the change. However, neither soil structural measures determined with X-ray tomography nor nematode density showed systematic alteration after the land-use change. Our results suggest that slow accumulation of carbon in soil leading to elevated carbon stocks can be easily lost if the favourable soil management ceases, which calls for long-term commitment to carbon conservation practices if lasting impacts are strived for.
