Search Results (28)

Alfalfa (Medicago sativa L.) is widely recognized as a major forage crop, yet its role as a multifunctional biological input in sustainable horticultural production remains underexplored. This review evaluates alfalfa as a biological nitrogen source, organic fertilization resource, and biofertilizer-supporting crop within vegetable, medicinal, and perennial horticultural systems. Due to its high capacity for biological nitrogen fixation, alfalfa can supply substantial amounts of plant-available nitrogen, reducing dependency on synthetic fertilizers and supporting environmentally sound nutrient management. When used as green manure, cover crop, intercrop, mulch source, compost feedstock, or processed organic fertilizer, alfalfa enhances the soil organic carbon (SOC), improves soil structure, and increases the water-holding capacity properties particularly critical in intensive horticultural production. Higher SOC levels also contribute to the improved tolerance of horticultural crops to drought and heat stress through enhanced soil moisture retention and rhizosphere buffering. Alfalfa-based organic inputs stimulate rhizosphere microbial biomass, enzymatic activity, and functional genes associated with nitrogen cycling, strengthening plant–microbe interactions that underpin biofertilizer effectiveness. Evidence from vegetable and perennial systems indicates that alfalfa-derived amendments and rotations increase soil nitrogen availability, support yield stability, and improve soil health over the long-term. In orchards and vineyards, alfalfa cover cropping contributes to carbon sequestration, erosion control, and enhanced soil biological functioning. Overall, alfalfa emerges as a strategic species for integrating organic fertilization and biofertilizer-based approaches into modern horticultural systems, supporting reduced mineral fertilizer inputs while sustaining productivity, soil health, and environmental quality. Full article

Soil organic carbon (SOC) responds rapidly to vegetation changes, and exploring SOC sequestration mechanisms under different vegetation types is critical for optimizing wetland carbon sink functions. This study investigated the abiotic and biotic mechanisms driving SOC stability across four typical vegetation types (reed marsh, woodland, farmland, and wasteland) in the 0–10 cm and 10–20 cm soil layers of Hengshui Lake wetland. Results showed that reed marshes exhibited the highest total organic carbon (TOC) and particulate organic carbon (POC), owing to anaerobic soil conditions and stable macroaggregate physical protection. Woodlands accumulated higher dissolved organic carbon (DOC) and microbial biomass carbon (MBC) via an efficient microbial carbon pump, despite weaker aggregate stability. In contrast, farmlands and wastelands presented intense labile organic carbon (LOC) turnover and enzymatic decomposition, accelerating SOC mineralization and carbon dissipation with poor carbon sequestration capacity. Proteobacteria and Acidobacteriota dominated bacterial communities, while Ascomycota prevailed in fungi. Soil water content (SWC) and bulk density (BD) were the core drivers of microbial community succession, and fungi were more sensitive to vegetation changes. Conclusively, distinct vegetation types shape divergent SOC sequestration pathways. This work provides a theoretical basis for wetland restoration and regional carbon sink enhancement. Full article

Cover crops (CCs) provide key ecosystem services, including nitrogen (N) retention and increased soil organic carbon (SOC), although their short-term benefits may be limited in dry continental climates. This study assessed a conservation system combining CC and non-inversion tillage (MT+CC) over a full crop rotation (sunflower–winter wheat–corn–sunflower) in south-eastern Romania, compared with plough-based tillage (PT). A randomized block design was conducted on a clay loam Luvisol, and N retention was estimated annually from soil mineral N and the biomass and N content of CC and weeds. MT+CC increased N retention during the first three years (+20.30 kg ha⁻¹ before corn; +26.67 kg ha⁻¹ before sunflower), but this advantage declined, and in year four PT showed higher N retention due to intensive weed growth. MT+CC reduced corn and sunflower yields, likely because of water competition and temporary N immobilization, but increased winter wheat yields. After four years, SOC was significantly higher under MT+CC (1.42%) than PT (1.37%), while total N remained unchanged, resulting in a higher C:N ratio. Consequently, in continental climates, CC use has a limited N retention potential, and excessively late CC sowing and termination is risky in crop rotations dominated by high-N-demand spring crops. Full article

Robust quantification of greenhouse gas (GHG) balances in tea plantations is critical for evaluating their contribution to agricultural carbon neutrality. This study aimed to develop data-driven models to quantify soil organic carbon (SOC) sequestration and N₂O emissions in Chinese tea plantations, evaluate their net GHG balance at the national scale, and assess the mitigation potential under alternative nitrogen management scenarios. Using a comprehensive national dataset, we compared multiple machine learning (ML) approaches with a conventional multiple linear regression (MLR) model to simulate N₂O emissions and SOC changes in Chinese tea plantations. All ML models substantially outperformed the MLR model, with the Random Forest (RF) algorithm achieving the highest predictive accuracy. The RF models yielded R² values of 0.68 for N₂O emissions and 0.67 for SOC changes, with no significant prediction bias. Variable importance and marginal effect analyses revealed strong non-linear controls. Mineral N fertilizer input was the dominant driver of N₂O emissions, followed by organic N input, soil clay content, and SOC. In contrast, SOC dynamics were primarily regulated by organic carbon inputs, tea plantation age, climate variables, and soil pH. National-scale simulations indicated an average N₂O emission intensity of 9.03 kg N₂O ha⁻¹ yr⁻¹ and a mean SOC sequestration rate of 0.88 t C ha⁻¹ yr⁻¹. Overall, SOC sequestration offset N₂O emissions, rendering Chinese tea plantations a net GHG sink (−2525 Gg CO₂-eq yr⁻¹). Scenario analyses showed that mineral N reduction increased net GHG uptake by 1804 Gg CO₂-eq, while organic fertilizer substitution achieved a substantially larger mitigation potential of 5961 Gg CO₂-eq. By integrating SOC sequestration and N₂O emissions within a unified modeling framework and applying machine-learning-based national-scale simulations, this study provides a more comprehensive and data-driven quantification of GHG balances in tea ecosystems, offering a scientific basis for evaluating their role in agricultural carbon neutrality strategies. Full article

Winter wheat (Triticum aestivum L.) productivity in intensive rice–wheat systems of the Jianghan Plain is constrained by sub-optimal nitrogen (N) management and residue handling. Straw residue return (SRR) can increase soil organic carbon and improve soil structure but may also immobilize N and alter the temporal pattern of soil mineral N (SMN). Although straw return and N fertilization have been widely studied, the combined effects on SRR and N applications on wheat yield and soil N dynamics in this region remain insufficiently resolved. In this study, we evaluated three SRR levels (0, 50, and 100% of approximately 3.5 t rice straw ha⁻¹) combined with four N application treatments over three years of field trials in the Jianghan Plain of Yangtze River Basin. Treatments were arranged in a randomized complete block design. Our results show that wheat performance is closely associated with SMN (NO₃⁻-N, NH₄⁺-N, total N) at 0–20 soil layers from booting to maturity. Grain yield increased sharply with N application, with SRR further enhancing yield. The combination of a 100% SRR and 70/30 basal-to-overwinter N split with a total N rate of 180 kg ha⁻¹ (T11) achieved the highest three-year mean grain yield. This superior performance was driven by optimized yield components, including a maximum of 55 grains per spike and a 1000-grain weight of 42.4 g under T11. Soil total N, nitrate-N, ammonium-N, and SOC were all significantly influenced by both N application timing and SRR. Across the three-year experiment, we concluded that 50–100% SRR combined with 70–100% basal N application represents an optimal agronomic practice for rice–wheat rotations in the Jianghan Plain. Full article

Mollisols represent foundational agricultural soils in which high organic carbon (C) and active microbiomes sustain fertility and mediate global C cycling. However, decades of intensive cultivation have depleted soil organic C (SOC) and degraded soil structure and function. Enhancing C sequestration in agricultural Mollisols through the incorporation of organic residue, such as crop residues, organic waste, and spent mushroom substrates has become an urgent scientific and management priority. This review integrates advances from the past decade, combining stable isotope probing, multi-omics analyses, and ultrahigh-resolution molecular characterization to elucidate how microorganisms mediate C sequestration during organic residue return and decomposition. We propose a four-dimensional conceptual framework, “substrate–microenvironment–metabolic pathway–residue stabilization,” that links microbial metabolism with long-term C persistence in Mollisols. We further highlight that organic residue inputs promote CO₂ sequestration via fermentation–autotrophy coupling, nitrifying autotrophy, and microbial mixotrophy. Major C sequestration pathways operate synergistically across redox microenvironments, forming stratified metabolic networks that sustain continuous C cycling. The chemical composition and decomposition kinetics of organic residue governs substrate and energy fluxes for microbial C sequestration, while soil redox status, and nutrient coupling (Carbon–Nitrogen–Phosphorus–Sulfur) collectively direct C flow toward stabilization. Microbial necromass and extracellular polymers achieve long-term C storage through mineral adsorption and microaggregate formation. Finally, we summarize recent methodological advances for tracing microbial CO₂ sequestration in agricultural Mollisols and identify key research needs on residue formation, C use efficiency, and aggregate-mineral protection mechanisms. This synthesis establishes a mechanistic foundation for biologically regulated C management and offers guidance for sustainable cropland restoration. Full article

Sloping cropland on the Loess Plateau faces severe challenges from soil organic carbon (SOC) depletion and structural instability due to erosion and intensive tillage. Although mulching can enhance SOC sequestration, its long-term effects on the spatial distribution of SOC and aggregates across slopes remain unclear. A 15-year field experiment evaluated five practices—conventional tillage (T), no tillage (NT), straw mulching (SM), plastic film mulching (PM), and ridge–furrow plastic film mulching (RPM)—on SOC storage, aggregate stability, and their variation with different slope positions. Compared to T, all mulching treatments significantly increased SOC concentration by 4.19% to 83.48% in the 0–30 cm layer. SM and RPM notably increased macro-aggregates (>2 mm) and their associated SOC (24.04–56.49% higher than T) by adding organic matter and optimizing micro-topography. Different slope positions strongly influenced SOC redistribution: lower slopes accumulated more SOC than upper slopes due to erosion–deposition processes. Mulching reduced SOC spatial variability and minimized differences between slope positions. Although mulching increased cumulative SOC mineralization compared to T, the long-term net SOC gain was positive, driven by improved aggregate protection and reduced erosion. SM and RPM are recommended for sustainable slope farmland management due to their dual benefits in enhancing carbon sinks and soil stability. This study offers practical strategies for improving soil health and SOC sequestration in vulnerable sloping landscapes. Full article

Intensive agriculture, ecosystem degradation, and declining soil quality highlight the urgent need for sustainable land use strategies. The cultivation of short-rotation woody crops (SRC), combined with fertilization using sewage sludge digestate (SSD), offers a promising approach to recycle nutrient-rich waste and promote soil organic carbon (SOC) accumulation. This study evaluated SOC concentrations, stocks and their spatial distribution in the 0–20 cm soil layer under SRC cultivation, with and without SSD fertilization, across contrasting soil types in Eastern Lithuania. The investigated soils included mineral (Luvisols (LV), Retisols (RT), Planosols (PL), Arenosols (AR)), organo-mineral (Gleysols (GL)), and organic soils (Histosols (HS)), representing textures from sand to peat and classified according to the World Reference Base for Soil Resources (WRB). Part I assessed baseline SOC variability in unproductive areas planted with hybrid poplars (Populus spp.) and hybrid aspen (Populus tremula × P. tremuloides) up to 20 years old. Part II examined SOC changes in three SRC fields of different ages (3–10 years), including unfertilized and SSD-fertilized stands. SOC concentrations increased consistently from mineral (1.14–1.80%) to organo-mineral (2.13–3.20%) and organic soils (6.37–17.53%). Heavier-textured soils accumulated more SOC than lighter soils, showing a strong positive correlation between SOC and soil texture (r = 0.82, p ≤ 0.01). SRC cultivation increased SOC across all soil types, while SSD fertilization further enhanced accumulation, with fertilized fields showing SOC increases of 0.50–1.07 percentage points and carbon stocks by 18.8–41.7 t ha⁻¹, compared with smaller increases in unfertilized fields. Spatial visualization of SOC further highlighted long-term accumulation patterns across soil types, confirming the trends observed under SRC cultivation and SSD fertilization. Full article

Enhanced silicate rock weathering (ESRW) has been proposed as a promising carbon dioxide removal strategy, yet its carbon sequestration pathways, durability, and ecosystem dependence remain incompletely understood. Here, we synthesize evidence from field experiments, observational studies, and modeling to compare ESRW-induced carbon dynamics across forest and cropland ecosystems using a unified SOC–SIC dual-pool framework. Across both systems, ESRW operates through shared geochemical processes, including proton consumption during silicate dissolution and base cation release, which promote atmospheric CO₂ uptake. However, carbon fate diverges markedly among ecosystems. Forest systems, characterized by high biomass production, deep rooting, and strong hydrological connectivity, primarily favor biologically mediated pathways, enhancing net primary productivity and mineral-associated organic carbon (MAOC) formation, while facilitating downstream export of dissolved inorganic carbon (DIC). In contrast, intensively managed croplands more readily accumulate measurable soil inorganic carbon (SIC) and soil DIC over short to medium timescales, particularly under evapotranspiration-dominated or calcium-rich conditions, although SOC responses are often moderate and variable. Importantly, only a subset of ESRW-driven pathways—such as MAOC formation and secondary carbonate precipitation—represent durable carbon storage on decadal to centennial timescales. By explicitly distinguishing carbon storage from carbon transport, this synthesis clarifies the conditions under which ESRW can contribute to climate change mitigation and highlights the need for ecosystem-specific deployment and monitoring strategies. Full article

The intensity of wildfires is projected to increase with the rising frequency of droughts due to climate change. Management practices following forest fires must include restoring the appropriate species composition. This study was performed within the wider context of the regeneration of soil properties, including the stock and soil organic matter (SOM) content, at the largest forest fire site in Poland (more than 9000 ha) in the Rudziniec Forest District, Upper Silesia. Research plots were established on sandy soils (Podzols and Arenosols) in pure stands of Scots pine (Pinus sylvestris L.), common birch (Betula pendula Roth), and black alder (Alnus glutinosa (L.) Gaertn.). The organic and mineral soil horizons were sampled from each research plot and control plots unaffected by the fire. The trees’ foliage was also sampled to determine the nutrient supply. Basic soil properties were determined, including the texture, pH, bulk density, organic carbon (C), macronutrient contents, soil microbial biomass, and labile C and nitrogen (N) fractions. We found that, 30 years after the fire, the post-fire soils had similar SOC stocks (34.80 Mg ha⁻¹) to the control plots (31.72 Mg ha⁻¹); however, they differed in their stocks of labile C and N fractions. The post-fire soils had a less stable C pool due to a higher stock of the fraction associated with particulate organic matter. In contrast, the N pool was more stable in the post-fire soils than in the control soils due to a lower contribution of the most labile fractions. The soils under Scots pine had the least stable SOM, which may have influenced the intensification of the podzolization process, whereas the highest biomass of soil microorganisms was observed under common birch. The soils under black alder had the highest acidity and lowest phosphorus (P) content. The C:N:P ratios in the post-fire soils and tree foliage indicated that P may have been the limiting factor in alder growth, and N for pine and birch. Our findings indicate that tree species composition is an important factor in the recovery of post-fire soil properties. However, the introduction of pure black alder stands to post-fire soils with low moisture and P availability showed little effectiveness in restoring the SOM content and N pool. Full article

This study aimed to evaluate the impact of vineyard cultivation time and the use of metal-based fungicides on the chemical fractions of soil organic matter (SOM) as well as their interactions with Cu, Zn, and Mn in vineyard soils from Southern Brazil with varying histories of fungicide application. Soil samples were collected in 2017 from vineyards aged 35, 37, and 39 years in the Serra Gaúcha region and 13, 19, and 36 years in the Campanha Gaúcha. In each region, samples were also collected from a non-anthropized reference area. In the oldest vineyards, sampling was conducted both within and between the rows of planting. Chemical fractionation of SOM was performed: non-humic substances (nHSs), particulate organic matter (POM), fulvic acid (FA), humic acid (HA), and humin (Hu). Fourier-transform infrared (FTIR) spectra were obtained for the HA, from which the aromaticity index (AI) and relative intensities (RIs) were calculated. In each SOM fraction, total organic carbon and the concentrations of Cu, Zn, and Mn were determined. Changes in land use alter the forms and distribution of soil organic carbon (SOC) and, consequently, of metals. Elemental and spectroscopic analyses of HS revealed that HA in the reference areas (forest and native grassland) was more aliphatic and had higher concentrations of polysaccharides, indicating fractions with a lower degree of stabilization. However, in vineyard areas, HA exhibited greater humification and aromaticity. Increasing cultivation time gradually increased soil carbon content, indicating that viticultural agroecosystems can sequester carbon in the soil over time, reaching levels similar to those observed in the reference areas. When comparing vineyard areas alone, with row collections and inter-row collections, we observed an increase in SOC levels in areas managed with cover crops, demonstrating the importance of conservation management in these areas. When evaluating the distribution of metals in these soils, we could observe the high affinity of Cu for the functional groups of SOM, with FA and HA responsible for the complexation of these elements in the soil. For Zn and Mn, the greatest accumulations were observed in the Hu fraction due to their greater affinity for soil clay minerals. This shows that soil organic matter is a key component in the complexation of metals in soils, reducing their availability and potential toxicity to cultivated plants. Full article

Climate change aggravates the frequency of extreme rainfall events, resulting in carbon (C) loss. For the special climate of the highlands, cultivating the land underneath orchards increases C reservation. Systematic research on the impact of extreme rainfall on soil organic carbon compositions and (dissolved organic carbon) DOC leaching is limited, especially regarding the response to different cropping patterns underneath orchards, requiring a deeper understanding. The results showed that the DOC-leaching fluxes for the cropping patterns under rainstorms and heavy rainstorms were in the order Dactylis glomerata L. monocropping (13.5, 4.4 kg/hm²) > Medicago sativa L. monocropping (11.2, 3.8 kg/hm²) ≥ D. glomerata. + M. sativa. (10.4, 3.6 kg/hm²). The DOC-leaching fluxes during heavy rainstorms were reduced with D + M, and the root morphology showed a significant correlation with DOC concentration. Compared to the D, SOC in layers 40–60 cm of the M and the D + M increased by 68.36% and 64.24%, respectively. TP and POC of the D + M increased with soil depth. Relationships between cropping pattern and rainfall intensity for particulate organic carbon (POC) and mineral-associated organic carbon (MOC) were observed. Heavy rainstorms reduced MOC, including the decomposition of substances related to the MOC, such as ROC and DOC, then POC in layers 40–60 cm increased; compared with 0–20 cm of D and M, the content of readily oxidizable carbon (ROC) in layers 40–60 cm reduced by 56.90~77.64%, and the POC increased by 38.38~87.00% in the D + M. Therefore, it was suggested that the decomposition of deeper MOC due to heavy rainstorms is the main source of soil POC and leaching DOC. This will provide a reference basis for research on assessing soil carbon-leaching fluxes and carbon stocks under extreme rainfall events. Full article

Intensive agricultural management affects the physical, chemical, and biological properties of soil, potentially contributing to a decrease in soil carbon storage. In this study, the effects of soil management intensity on soil organic carbon (SOC) content and its labile fractions, i.e., water-soluble organic carbon (OC-sol) and permanganate oxidizable carbon (POXC), were evaluated in a volcanic-ash-derived soil (Andisol) with a very high soil organic matter (SOM) content (>20%). These indicators were associated with water-stable aggregates (WSAs) and biological indicators, namely, earthworm density, cellulase activity, and autoclaved-citrate-extractable (ACE) proteins, related to the decomposition of SOM and its physical protection. The conditions evaluated were secondary native forest (SF), naturalized grassland (NG), no-till (NT), and conventional tillage (CT), considering the last item to be representative of a higher agriculture management intensity. Soil samples were collected by horizon. The SF and NG soil showed higher contents of SOC, OC-sol, and POXC. When comparing the evaluated annual cropping systems, NT showed higher values than CT (p < 0.05) in the first horizon (Hz1), while similar values were found at deeper horizons. The highest cellulase activity, ACE protein levels, and earthworm densities were found in NG and SF. NT also showed significantly higher levels of the aforementioned factors than CT (p < 0.05). A positive and significant relationship was found between the SOC content and WSA (R² = 0.76; p < 0.05) in the whole profile and between POXC and WSA for Hz1 (R² = 0.67; p < 0.05). Soil C storage was affected by the intensity of agricultural management, mainly because of the effect of tillage on structural stability, considering that biological activity synthesizes compounds such as enzymes and proteins that react and adhere to the mineral fraction affecting aggregate stability. The C content stored in the soil is consequently a key indicator with which to regulate SOM and protect SOC. Full article

The important role of soil carbon pools in coping with climate change has become widely recognized. Moso bamboo (Phyllostachys pubescens) is an economically important bamboo species in South China; however, owing to factors such as rising labor costs and increasingly stringent environmental policies, Moso bamboo forests have recently been abandoned. The present study aimed to investigate the effects of abandonment on structural factors and soil organic carbon (SOC) stocks in Moso bamboo forests. We investigated Moso bamboo forests subjected to intensive management or abandonment for different durations and measured forest structural characteristics, mineral properties, soil nutrients, and other soil properties. Although abandonment did not significantly affect the height and diameter at breast height, it increased culm densities, biomass, and SOC stocks. The drivers of SOC stocks depended on soil depth and were mainly controlled by carbon decomposition mediated by soil properties. In the topsoil, mineral protection and soil total nitrogen (TN) exerted significant effects on SOC stocks; in the subsoil, soil TN was the main driver of SOC stocks. As the controlling factors of SOC stocks differed between the subsoil and topsoil, more attention should be paid to the subsoil. Overall, these findings refine our understanding of the structural characteristics and SOC stocks associated with Moso bamboo forest abandonment, serving as a reference for the follow-up management of these forests. Full article

Fresh-cut leafy vegetables are produced in Southern Italy in very intensive crop systems under tunnel greenhouses in which continuous cropping has triggered soil organic carbon (SOC) depletion and the risk of degradation of soil fertility. A two-year trial of soil organic amendment was carried out on a private farm producing baby-leaf crops on a very poor OC soil (<1%). Biowaste compost, two types of olive pomace composts and buffalo manure were compared to evaluate their ability to recover a positive SOC balance and sustain crop growth and yield. The effects on soil health and crop system were studied by measuring different aspects such as SOC stock change and SOC sequestration rate, soil microbial biomass and nine enzyme activities, yields of rocket and concentration of nitrates in leaves. Soil amendments were distributed once a year at doses of 15 and 30 Mg ha⁻¹ as fresh matter without integration of mineral fertilizers. In our study, the SOC stock improved in the amended soils in a range of 4–6 Mg ha⁻¹, except for dose 30 of buffalo manure, with the highest values where biowaste compost was applied. Our data showed an increase in biological parameters in all the amended soils with respect to Control. In soil amended with olive pomace, however, compost mineralization rates likely did not match crops’ nutrient needs so the yields of rocket were lower than with the biowaste compost and buffalo manure. Biowaste compost showed the best results as it balanced the best C conversion efficiency, the higher increment of SOC and yields of rocket. Full article