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Microbial leftovers, known as necromass, are key players in storing carbon in the soil around plant roots (i.e. rhizosphere), a zone characterized by high‐efficiency microbial anabolism. Yet, the extent and mechanisms through which the rhizosphere contributes to soil organic carbon (SOC) via microbial necromass, especially under changing environments remain unclear. We aimed to evaluate the contributions of microbial necromass to SOC and influencing factors from the rhizosphere perspective. We collected the rhizosphere and bulk soil from 39 alpine coniferous forest sites on the eastern Tibetan Plateau to assess the extent of microbial necromass contribution to SOC in the rhizosphere from a dynamic perspective by calculating the ratio of increased amino sugars (AS) to increased SOC in the rhizosphere relative to that in bulk soil (RAS/SOC). We also collected climate data and determined nutrient concentrations and microbial physiological traits in rhizosphere soil to elucidate the factors affecting RAS/SOC. The results showed that across all sampling sites, the average concentrations of SOC‐normalized AS in the rhizosphere were significantly higher than those in the bulk soil. Furthermore, the average RAS/SOC was greater than 1, indicating a faster microbial necromass accumulation than SOC accumulation in the rhizosphere. These results implied that the rhizosphere sustains a greater capacity for microbial necromass contribution to the SOC pool than the bulk soil does. Soil nutrient availability was the primary factor affecting RAS/SOC, and precipitation indirectly affected microbial anabolism and RAS/SOC by changing soil nutrient status. Additionally, with increasing rhizosphere soil nutrient availability, microbial carbon‐use efficiency and growth rate increased but the biomass‐specific enzyme activity declined, indicating that microorganisms tended to exhibit high‐yield strategies with increasing soil nutrient availability. Synthesis. Our findings underpin the vital effect of microbial necromass in SOC accumulation from the rhizosphere perspective and offer valuable insights into mechanisms underlying microbial C metabolic processes in rhizosphere SOC accumulation under changing environments. [ABSTRACT FROM AUTHOR]

Soil Organic Carbon (SOC) is an important indicator for soil health and quality. The present study was conducted in five-decade-old Long-Term Fertilizer Experiment involving the finger millet−maize cropping sequence in an Inceptisol to examine the effects of inorganic fertilizers and manures on soil organic carbon stock in relation to C sequestration. This study was based on 10 treatments: 50%NPK, 100%NPK, 150%NPK, 100%NPK + HW, 100%NPK + ZnSO4, 100%NP, 100%N, 100%NPK + FYM, 100%NPK (− S), and control. We assess the clay mineral interaction with soil organic carbon stock and soil enzyme activity. The semi-quantification and characterization of clay minerals were sourced from X-ray diffraction (XRD) analysis, and the SOC stock was calculated based on SOC concentration, Bulk density, and Depth. From the study, results revealed that clay minerals were studied by XRD and FTIR spectroscopy analysis. The results revealed that dominant clay minerals in the experimental soil were in the order of Montmorillonite, 2:1 interstratified minerals, Vermiculite, and Illite, and the buildup of SOC stock raised from 6.3 Mg C ha−1 to 12.9 Mg C ha−1 over five decades. The maximum SOC stock of 12.9 Mg ha−1 was recorded in 100% NPK + FYM while the control registered 7.5 Mg C ha−1. The study conclude that balanced fertilization of 100% NPK with FYM contributed toward the increase in SOC, SOC stock, and carbon sequestration for improving soil fertility status. [ABSTRACT FROM AUTHOR]

The impact of different vegetation types on soil organic carbon (SOC) is a key focus in global warming research. Bryophytes, commonly found in karst urban forests, significantly contribute to carbon accumulation in surface soil. However, the changes in soil organic carbon fractions under moss and the influencing factors remain unclear. To address this knowledge gap, the study examined the organic carbon content, soil physicochemical properties, and associated environmental factors in both moss-covered soil and bare soil under six different forest species within an urban park. The results showed that the SOC contents under moss cover in evergreen coniferous forest (127.28 g/kg), bamboo forest (144.70 g/kg), deciduous broad-leaved forest (87.63 g/kg), and evergreen shrub (109.28 g/kg) were significantly higher compared to bare soil. Moss cover also had a significant impact on soil readily oxidizable carbon (ROC), particulate organic carbon (POC), mineral-associated organic carbon (MOC), and heavy fraction organic carbon (HFOC) (P < 0.01). The soil under moss had a higher content of stable organic carbon fraction, which is conducive to the stability of the soil organic carbon pool. The interaction between moss cover and stand type had the most significant effect on soil organic carbon, especially in bamboo forests. Canopy density, moss biomass, and soil moisture were the main environmental factors affecting the content of soil organic carbon and its fractions, while soil organic carbon content was mainly affected by soil nitrogen and phosphorus. This study establishes a theoretical framework for investigating the carbon cycle in karst urban underforest ecosystems, offering a scientific basis for the management and preservation of urban green space ecosystems. Future studies should include bryophytes in the assessment of dynamic factors affecting the soil carbon pool under forest cover and further explore the function and ecological significance of bryophytes in understory ecosystems. [ABSTRACT FROM AUTHOR]

Organic agricultural practices are increasingly recognized for promoting sustainable soil–plant-environment interactions. However, the specific impact of soil additives in organic systems on nutrient and microbial dynamics, and their subsequent effects on crop performance, are still relatively unexplored. This study sought to address this gap by investigating the screening of suitable rice-legume residue combinations for biochar (BC) production and assessing the effect of incorporating BC as a soil additive in organic soil nutrient management. A two-year field experiment was conducted with six organic soil treatments comprising farmyard manure (FYM) and vermicompost (VC) as organic nutrient sources (equivalent to 100 kg N ha−1), along with BC and Jeevamrit (J-Con) as soil additives, and a non-fertilized control to evaluate their impacts on nutrient cycling and crop performance. The rice-pigeon pea crop residue combination was found to be the most suitable for BC production (BC-RP), maintaining favorable nutritional quality and conversion efficiency. Among the soil treatments, T5 (50% FYM + 50% VC + BC) emerged as the most effective for enhancing soil pH, carbon content, and nutrient and microbial dynamics, followed by 50% FYM + 50% VC + J-Con (T6). This treatment also notably improved crop (onion) parameters, including growth, yield, quality, and production economics. The incorporation of BC as soil additive in 50% FYM + 50% VC significantly enhanced nutrient and microbial transformations in the soil, resulting in improvements of 7–25% in crop parameters. The findings of the study thus may be useful for achieving sustainable onion production by enhancing synchronized soil–plant interactions within an organic production system. [ABSTRACT FROM AUTHOR]

A test plot of 15 ha in area has been set as a climate monitoring facility in Shchelkovo district, Moscow oblast, in 2022. Within the boundaries of the test plot, which represents one forest survey unit, a significantly diverse soil cover has been revealed, i.e., 18 soil varieties ranging from subtype to subspecies. Microrelief is considered to be the main factor of carbon stock heterogeneity: the soils of closed depressions occupied by sphagnum mosses differ significantly in carbon stocks in the litter and in the upper 10 cm of soil. For the rest of the territory, the main factors influencing the carbon stock are the percentage of physical clay in the illuvial part of the soil profile, as well as the composition and phytomass of ground vegetation. The highest variation coefficient in C stocks (40%) was registered for the 10–30 cm layer, being due, above all, to the varying thickness of the genetic horizons composing it. Geospatial analysis allows us to pass to the spatial assessment of variation in soil properties and further modeling and forecasting the carbon stock dynamics taking into account the spatial heterogeneity of the territory. Identifying the factors that control carbon stocks in soils will help to work out modeling scenarios aimed at developing measures on increasing carbon accumulation in forest ecosystems through changes in the vegetation structure. [ABSTRACT FROM AUTHOR]

Globally, the widespread utilization of plastic products has resulted in the accumulation of microplastics (MPs) in the soil. MPs have the potential to impact the loss of soil organic carbon (SOC). Nevertheless, the influence of different types of MPs on SOC loss remains uncertain.In this study, a 38 day incubation experiment with two kinds of conventional MPs (polyethylene, polypropylene) as well as two kinds of biodegradable MPs (polyhydroxyalkanoate [PHA], polylactic acid [PLA]) were added into three types of soil (loam, sandy loam, and sandy soil) in farmland shelterbelts, and the sources of CO2 emissions was distinguished by the difference in 13C isotope abundance between the biodegradable MPs (PHA and PLA) (−10.02‰ to −9.92‰) and the soil (−24.39‰ to −22.86‰) (>10‰).In conjunction with the structural characterization of MPs, as well as soil physicochemical properties and microbial characteristics, we observed that the conventional MPs did not degrade in short term incubation, but significantly enhance soil‐derived CO2 emissions by altering the dissolved N content (NH4+‐N and dissolved total N [DTN]) and reducing microbial biomass carbon content only in sandy loam soil (p < 0.05). Biodegradable MPs degraded significantly, and enhanced soil‐derived CO2 emissions by reducing soil DTN and NO3−‐N contents in loam, sandy loam and sandy soil (p < 0.05).Overall, the input of biodegradable MPs causes a more serious loss of SOC than conventional MPs as the soil sand content increased in short term incubation, which needs to be considered in predicting the global impact of increasing biodegradable MPs pollution. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Quantifying the effects of environmental factors on soil organic carbon and spatial distribution is fundamental to soil quality regulation, restoration, and response to climate change. The present study aims to explore the spatial distribution characteristics of the soil organic carbon (SOC) contents in Anhui Province, China, based on national soil data. In addition, we used the geographically weighted regression (GWR) model to quantify the influence degrees of environmental factors on the soil organic carbon density (SOCD). The results showed that the spatial distribution of SOCD in Anhui Province in both 1985 and 2018 was characterized by high in the south and low in the north. The GWR model prediction results of the 0–30 cm SOCD showed local coefficients of determination (local R2) ranging from 0.21 to 0.96 and 0.14 to 0.96 in 1985 and 2018, respectively. Therefore, the predicted results were effective in evaluating the overall spatial distribution of the SOCD in Anhui Province. The regression coefficients of the normalized difference vegetation index (NDVI) and air temperature ranged from − 0.39 to 5.67 and − 0.17 to 3.11, respectively, demonstrating their strong controlling effects on the spatiotemporal variations in the 0–30 cm SOCD in Anhui Province. [ABSTRACT FROM AUTHOR]

Changes in land use from high-nature-value grasslands to arable fields reduce the organic carbon stock in soil, increasing atmospheric carbon concentrations. Maintaining grasslands through traditional agricultural techniques can mitigate climate change by transferring atmospheric carbon to the soil. Benefits of soil organic carbon sequestration include improved soil properties and enhanced ecosystem services and biodiversity. With Romania's ratification of the Paris Agreement, it is crucial to review climate-related agricultural policies and incentivize carbon sequestration practices in organic soils. This paper presents a soil carbon study in Transylvania's Târnava Mare region, Romania, known for its preserved cultural landscapes. Soil samples were taken at a depth of 60 cm to assess organic carbon pools under grassland and arable land management across three soil classes: Cernisoils, Hidrisoils, and Luvisoils. Several statistical tests were applied to evaluate the most significant drivers of soil organic carbon sequestration including land use, soil class, and soil depth. The results indicate that land management has the largest impact, with grasslands storing 45% more carbon than arable land on average. This finding should be integrated into national climate action plans, prioritizing the preservation of grasslands and sustainable agricultural practices to support soil organic carbon sequestration. [ABSTRACT FROM AUTHOR]

Straw biochar is an effective amendment at improving soil aggregate structure and increasing soil carbon and potassium (K) content. However, little information is available on the relationship between soil organic carbon (SOC) and aggregate‐associated K distribution under long‐term biochar application conditions. To address this, a field trial established in 2013 was used to examine the impact of biochar (B0: 0 and B1: 2.625 t ha−1 year−1) and K fertilizer (K0: 0 and K1: 60 kg ha−1 year−1) on the variation in soil aggregate K and reveal the associated influencing factors. A total of four treatments (B0K0, B0K1, B1K0, and B1K1) were included in this study. The soil analysis results obtained in 2021 showed that after 9 years' amendment, B1K1 increased the aggregate exchangeable K (EK) and nonexchangeable K (NEK) pools by 27.40% and 39.55%, respectively, and the increment was primarily because biochar enhanced > 0.25 mm aggregate fractions and strengthened soil K+ adsorption capacity, which benefit from a synergistic increase in SOC and humic acid (HA) content by biochar. 13C NMR analysis showed that long‐term biochar applications altered the chemical composition of SOC, with an outcome of increased aromaticity and hydrophobicity but decreased the lipidation of SOC, indicating that the complexity of SOC molecular structure was enhanced and eventually contributed to strengthening the macroaggregates stability and soil K+ adsorption capacity. The correlation analysis revealed that soil aggregate EK and NEK contents were positively correlated with SOC and HA contents, which further proved that increase of SOC and soil HA is a significant mechanism for biochar ameliorate soil aggregate‐associated K availability. [ABSTRACT FROM AUTHOR]

The impact of various organic amendments on soil organic carbon (SOC) have rarely been reported. To address this, a laboratory experiment was designed to scrutinize the effects of different amendments on soil carbon fractions, microbial communities, and the underlying interactive mechanisms. The experiment encompassed a no-amendment control (CK), as well as treatments with corn straw (CS), tobacco stalks (TS), and peanut shell biochar (PB). Over a 70-day incubation, the SOC in plots amended with CS, TS, and PB displayed significant boosts of 13.9%, 17.5%, and 44.8%, respectively, compared to the CK. For soil carbon fractions, amendments with PB, TS, and CS led to a dramatic rise in particulate organic carbon (POC) of 27.4%, 20.2%, and 105.7%, respectively, in contrast to the CK plots. Mantel analysis and structural Equation Modeling uncovered strong interrelationships among the cbbL, cbbM, Bacteroidota, TOC, and POC. Organic amendments enhance soil carbon fractions, modulating the microbial community by increasing Bacteroidetes abundance and suppressing Acidobacteria richness, thereby influencing the abundance of key carbon cycle genes such as cbbL and cbbM. These results suggest that the addition of peanut shell biochar significantly boosted TOC and key carbon fractions, enhancing carbon content and soil fertility. [ABSTRACT FROM AUTHOR]

Karst ecosystems, especially tropical karst forests, are crucial to the global carbon cycle. In mountainous and hilly areas, elevation-related changes in environment and vegetation often lead to shifts in the accumulation and decomposition of soil organic carbon (SOC). However, the elevational patterns and influencing variables of SOC and its fractions in tropical karst forest ecosystems remain largely unexplored. Here, we analyzed the elevational patterns of SOC and its fractions in the topsoil and subsoil in the tropical seasonal rainforests within typical peak-cluster depression region of Southwest China. Our results indicated that the SOC content was highest at 400 m asl, which was significantly higher than that at 200 m asl (p < 0.05). Overall, SOC content demonstrated an increasing trend with rising elevation. Additionally, SOC content was significantly higher in the topsoil compared to the subsoil (p < 0.05). The majority of SOC fractions exhibited an increase with elevation but decrease with soil depth. Notably, only water-soluble organic carbon (WSOC) displayed a decrease with elevation. Meanwhile, recalcitrant organic carbon (ROC, 54.27%), particulate organic carbon (POC, 30.19%), and easily oxidizable organic carbon (EOC, 16.95%) were the main SOC fractions. Labile organic carbon (LOC) in the karst forest soil was predominantly composed of EOC and POC. Correlation analysis unveiled significant positive correlations between SOC and certain fractions with elevation, soil total nitrogen, and exchangeable magnesium. Conversely, significant negative correlations were observed with soil bulk density (SBD), soil total phosphorus, and litter phosphorus (Litter P). Redundancy analysis indicated that elevation, SBD, and Litter P were the main environmental variables influencing shifts in SOC and its fractions. Structural equation models showed that SOC was primarily directly impacted by soil properties but indirectly impacted by elevation. ROC was mainly associated with the direct effects of soil properties and litterfall, although elevation exerted a substantial impact through indirect pathways. Moreover, LOC was predominantly influenced by the direct impact of soil properties. Therefore, this study demonstrates that SOC and its fractions are strongly influenced by elevation in karst peak-cluster depression regions and have important implications for forest management and sustainable ecosystem development in these regions. [ABSTRACT FROM AUTHOR]

In flooded paddy fields, peak greenhouse gas nitrous oxide (N2O) emission after rewetting the dry soils is widely recognised. However, the relative contribution of biotic and abiotic factors to this emission remains uncertain. In this study, we used the isotope technique (δ18O and δ15NSP) and molecular-based microbial analysis in an anoxic incubation experiment to evaluate the contributions of bacterial, fungal, and chemical denitrification to N2O emissions. We collected eight representative paddy soils across southern China for an incubation experiment. Results show that during the 10-day incubation period, the net N2O emissions were mainly produced by fungal denitrification, which accounted for 58–77% in six of the eight investigated flooded paddy soils. In contrast, bacterial denitrification contributed 6–15% of the net N2O emissions. Moreover, around 11–35% of the total N2O emissions were derived from chemical denitrification in all soil types. Variation partitioning analysis (VPA) and principal component analysis (PCA) demonstrated that initial soil organic carbon (OC) concentrations were the primary regulator of N2O source patterns. Soils with relatively lower OC concentration (7–15 mg g−1) tend to be dominated by fungal denitrification, which accounted for the net N2O production at the end of the incubation period. Overall, these findings highlight the dominance of the fungal denitrification pathway for N2O production in flooded paddy soils, which predominates in soils with relatively lower OC content. This suggests that fungal contribution should be considered when optimizing agricultural management system timing to control N2O emissions in flooded paddy soil ecosystems, and for the relevant establishment of predictive numerical models in the future. [ABSTRACT FROM AUTHOR]

Although maintaining/improving soil organic matter (SOM) quantity through utilizing organic amendments (OAs) is a productive practice, information on OA components contributing to long-term SOM accumulation in agricultural soils remains meager. Hence, we examined soil samples from a long-term experiment with different fertilizer managements, including no fertilizer (NF), chemical fertilizer (CF) only (CF), bark compost plus CF (BC + CF), coffee residue compost plus CF (CRC + CF), cattle manure compost plus CF (CMC + CF), and cattle manure compost (CMC) or sewage sludge compost (SSC) alone at a higher application rate. SOM in those samples was physically fractionated into free particulate form (fSOM), free form occluded in aggregates (oSOM), weakly bound form (wSOM), and strongly bound form (sSOM). Analysis of structural components in OAs and SOM fractions using thermally assisted hydrolysis and methylation combined with gas chromatography/mass spectrometry (THM-GC/MS) revealed OA components that have contributed to long-term SOM accumulation in each treatment. The SSC was characterized by higher proportions of short-chain fatty acids (FAs; 50%) and other aliphatic compounds (22%). Correlation analysis suggested that these characteristics may be effective for greater C accumulation in the bulk soil and wSOM fraction. The proportion of lignin-derived phenols, e.g., 3,4-dimethoxybenzaldehyde (Vh) and 1,2-dimethoxy-4-(1,2,3-trimethoxypropyl)benzene, was high in CMC (43%), presumably vital for promoting C accumulations in the oSOM, wSOM, and sSOM fractions in the CMC treatment. The short-chain FAs in CRC and aromatic components in BC are likely important for contributing fSOM accumulation. [ABSTRACT FROM AUTHOR]

The replacement of farmland by native hygro-plants is increasingly common globally within the context of wetland ecosystem restoration. Understanding the long-term effects of this replacement on the abundance and persistence of soil organic carbon (SOC) in mountain marshes is important for soil carbon management. Here, the restored plateau mountain marshes of Duliu River Wetland Provincial Nature Reserve, China was selected. The properties, soil moisture content (SMC), pH, texture, free-form iron oxides (), amorphous iron oxides (), mineral-associated organic carbon (MAOC), and iron-bound organic carbon (Fe-OC) were analyzed in topsoil samples (0 ~ 20 cm) during the restoration of rice paddies to Sphagnum palustre L. wetlands for 0, 2, 10, and 20 years. Natural Sphagnum wetlands were also used as the control. We found that marsh restoration increased SMC, , , / , SOC, MAOC, Fe-OC, Fe-OC/SOC, but decreased the MAOC/SOC ratio. MAOC/SOC ratio of marshes were expectedly lower than the proportion of labile SOC in total SOC during the restoration period. SMC, SOC, and MAOC were higher in the natural Sphagnum wetlands than in other habitats. Both SOC and Fe-OC/SOC were positively correlated with SMC, , , / , and Fe-OC, but negatively correlated with soil pH. MAOC/SOC was negatively correlated with SMC, and / . These results emphasized the significance of reconverting rice paddies to marsh wetlands for increasing the sequestration of labile SOC and Fe-OC. Further studies are required to identify and quantify the organo-mineral stabilization mechanisms of SOC at the different SOC fractionations throughout the restoration period. [ABSTRACT FROM AUTHOR]

Based on the results of the 1 ∶ 250 000 regional geochemical survey projects completed in Henan Province from 2003 to 2020, the geochemical background values of total carbon and organic carbon in surface soil in Henan Province were systematically studied. The results showed that there were significant differences in the geochemical background values of total carbon and organic carbon in the surface soil of Henan Province in different administrative regions, watersheds and soils with different parent materials. The overall spatial distribution of the total carbon background value of surface soil in administrative regions showed that it was higher in the western mountainous areas and lower in the eastern plains, higher in the northern alkaline soil areas and lower in the southern acidic soil areas; the distribution of river basins decreased in sequence from the Haihe River Basin to the Yellow River Basin, then to the Huaihe River Basin, and finally to the Yangtze River Basin; the total carbon background value of soil developed from residual and residual slope deposits, river alluvial deposits, alluvial deposits, aeolian deposits, loess and red soil, and river lake sediments gradually decreases. The background values of surface soil organic carbon in administrative regions were generally higher in mountainous areas and lower in plains, and there were significant differences in the background values of surface soil organic carbon in different watersheds;the background value of soil organic carbon developed from residual and residual slope deposits, alluvial deposits, river lake sediments, loess and red soil, river alluvial deposits, and aeolian deposits gradually decreased. [ABSTRACT FROM AUTHOR]

Background and aims: In dryland regions, patches of vegetation play a crucial role in sequestering carbon and vital nutrients, creating what have been described as 'fertile islands' within the surface soil beneath their canopies. Nevertheless, a persistent question remains regarding the variability of fertile island effect in relation to soil depth. Methods: To investigate this, we sampled soils at two different depths (0–30 cm and 30–50 cm) within perennial vegetation patches and open areas across 54 drylands scattered across the Tibetan Plateau. Our study focused on six key soil variables related to carbon, nitrogen, and phosphorus stocks, allowing us to assess the differences in fertile island effects at varying depths. Results: Among the soil fertility parameters evaluated, organic carbon exhibited the most pronounced fertile island effect at both soil depths. The fertile island effect responded differently to environmental factors at the two depths assessed. In the surface soil layer, the impact of vegetation on soil carbon content intensified with increasing precipitation seasonality and precipitation in the wettest quarter but declined with increasing temperature during the driest quarter. Conversely, in the deeper soil layer, the fertile island effect for nitrogen and phosphorus intensified with greater soil sand content and vegetation greenness. Conclusions: The fertile island effect can extend beyond the surface soil, while different environmental factors regulate the size of this effect with depth. These findings offer fresh and valuable insights into the relationships between biotic and abiotic factors and fertile island effects, a key feature of dryland ecosystems worldwide. [ABSTRACT FROM AUTHOR]

Introduction Fallowing, which is one of the common practices in Iran's cropping systems, brings negative consequences such as soil erosion and reduction of its fertility, leaching of nutrients and, as a result, groundwater pollution. In addition, this practice increases weed infestation in an environment free of competition. Planting cover crops is one of the alternative methods to increase the quality and health of the soil and produce a healthy crop with minimal use of chemical inputs. Through competition and production and release of allelopathic substances in the soil environment, these crops are also considered as a suitable tool in suppressing weeds. The present study was conducted in order to investigate the effect of planting several species of cover crops as pure and mixed green manures on some soil characteristics and weed control. Materials and Methods This experiment was conducted in the form of a randomized complete block design with three replications in the Research Farm of Agriculture and Natural Resources Campus, Razi University, Kermanshah. Experimental treatments included cover crops of barley, common vetch and Persian clover in pure and mixed form at 10 levels: control (without cover crop), pure clover, pure barley, pure vetch, 50% barley + 50% clover, 50% barley +50 vetch, 50% vetch + 50% clover, 30% barley + 70% clover, 30% vetch + 70% barley, and 40% clover + 40% vetch + 20% barley. In order to cultivate cover crops, the land was first prepared by plowing and disk harrowing. Then, the seeds of cover crops were planted in plots of 7 × 6 m dimensions, using a furrower. The amount of seed used in the pure cultivation treatments of vetch, clover and barley was 60, 20 and 150 kg ha-1, respectively, and in the mixed treatments, different amounts of the seeds of each cover crop were planted based on the above-mentioned ratios. On the 30th of May (one month before planting potato) and at the stage when none of the cover crops had entered seed production stage, they were incorporated into the soil as green manures in two stages (one week apart) and at a depth of 10 to 15 cm. Results and Discussion The results showed that the cultivation of cover crops caused a decrease in pH and an increase in soil organic carbon compared to the control treatment, so that the lowest pH (7.32) and the highest soil organic carbon content (1.76%) were obtained from the pure barley treatment. Also, treatments of 40% clover + 40% vetch + 20% barley and 50% vetch + 50% clover caused a 38% and 36% increase in soil nitrogen, respectively, compared to the control treatment. The use of cover crops increased the content of phosphorus and potassium macronutrients in the soil both before and after potato harvest, compared to the control. The use of cover crops reduced the density of weeds in 20 and 40 days after potato cultivation, and the pure barley treatment reduced the density of weeds by 53 and 54%, respectively, compared to the control. The highest potato tuber yield was achieved under the treatments of 40% clover + 40% vetch + 20% barley and 50% vetch + 50% clover. The mentioned treatments increased the tuber yield by 71.09 and 59.79% compared to the control, respectively. The decrease in soil pH may be due to the accumulation of organic matter from crop residues and the acidification process during the mineralization of these residues, the increase in the amount of electrolytes, as well as the increase of microbial respiration and thereby the release of CO2 (5, 18). The increase in soil nitrogen availability following the application of green manures may have stemmed from the increase in root nodulation, release of a larger amount of nitrogen compounds by root nodules in the early stages of crop growth and their subsequent decomposition in later stages. Also, the increased nitrogen is at least partly due to the increase of organic matter through the return of biomass of cover crops in the cropping system (21). Covering the soil surface by cover crops and hence shading reduces weed seed germination and their subsequent growth due to competition of cover crops. In addition, during the decomposition of cover crop residues, allelopathic compounds are released in the soil environment, which affects the germination of weed seeds and establishment of their seedlings (15). Green manures obtained from cover crops increases moisture storage and improves soil fertility, enhancing the growth and yield of the main crop (16). Conclusions The results showed that the cultivation of cover crops instead of fallow increased the amount of organic carbon and macronutrients, despite decreasing the soil pH, leading to improvement in the access of the main crop to the soil nutrients. Weed control was another advantage of planting these crops. In the present study, the planting of leguminous cover crops with non-leguminous plants had the satisfactory results. [ABSTRACT FROM AUTHOR]

Biogeochemical models for predicting carbon dynamics increasingly include microbial processes, reflecting the importance of microorganisms in regulating the movement of carbon between soils and the atmosphere. Soil viruses can redirect carbon among various chemical pools, indicating a need for quantification and development soil carbon models that explicitly represent viral dynamics. In this opinion, we derive a global estimate of carbon potentially released from microbial biomass by viral infections in soils and synthesize a quantitative soil carbon budget from existing literature that explicitly includes viral impacts. We then adapt known mechanisms by which viruses influence carbon cycles in marine ecosystems into a soil‐explicit framework. Finally, we explore the diversity of virus–host interactions during infection and conceptualize how infection mode may impact soil carbon fate. Our synthesis highlights key knowledge gaps hindering the incorporation of viruses into soil carbon cycling research and generates specific hypotheses to test in the pursuit of better quantifying microbial dynamics that explain ecosystem‐scale carbon fluxes. The importance of identifying critical drivers behind soil carbon dynamics, including these elusive but likely pervasive viral mechanisms of carbon redistribution, becomes more pressing with climate change. [ABSTRACT FROM AUTHOR]

The remediation and exploitation of sandy saline soils, an underutilized resource, can be enhanced by a greater comprehension of the impact of plants and microorganisms on nutrient cycling. However, there is scant research information on the capacity of different trees and shrubs to improve carbon and nitrogen cycling in saline soils at different depth layers. This study investigated the effect of the trees Zelkova serrata (ZS) and Ligustrum lucidum (LL) and shrub Hibiscus syriacus (HS) on the carbon and nitrogen fractions, soil enzyme activities and microbial communities in sandy saline soils. Planting ZS, LL or HS improved soil quality, increased soil carbon and nitrogen content, changed rhizosphere soil metabolites and enhanced soil enzyme activities and microbial abundance and diversity. Compared to values in the bare soil, the highest reduction in soil salinity was noticed under Zelkova serrata (49%) followed by Ligustrum lucidum (48%). The highest increase in total soil organic carbon (SOC) was noted under Ligustrum lucidum and Hibiscus syriacus (62% each), followed by Zelkova serrata (43%), as compared to levels in the bare soil. In the 0–10 cm soil layer, the total N in bare soil was 298 ± 1.48 mg/kg, but after planting LL, ZS or HS, the soil total N increased by 101%, 56% and 40%, respectively. Compared with that of the bare soil, cbbL sequencing showed that the relative abundance of Bradyrhizobium increased and that of Bacillus decreased due to planting. Similarly, the nifH sequencing results indicated that the relative abundance of Bradyrhizobium and Motiliproteu increased and that of Desulfuromonas and Geoalkalibacter decreased. These findings suggested that soil microorganisms could play a pivotal role in the carbon and nitrogen cycle of saline soils by influencing the content of soil carbon and nitrogen. [ABSTRACT FROM AUTHOR]

In drylands, where the annual precipitation is low and erratic, improving the water storage capacity and the available water in the soil is crucial for crop production. To explore the effect of long-term agronomic management on water storage capacity and available water in the soil, four agronomic management systems were used (including the farmer's management model (FM), the high nitrogen input model (HN), the manure amendment model (MM), and the biochar amendment model (BM)) for eight consecutive years, and the variation in wheat yield and soil hydraulic, physical, and chemical properties in the 0–100 cm soil profile were investigated. The management practices varied in terms of seeding rates, nitrogen (N)-application strategies, and the application of manure or biochar. The results showed that, under the manure amendment model (MM), the wheat yield was increased by 17–35%, and the water-use efficiency was increased by 14–29% when compared to the farmer's management model (FM) and the high nitrogen input model (HN). However, no significant differences in wheat yield and water-use efficiency were found under the biochar amendment model (BM) compared to the HN. The high yield and water-use efficiency under the MM were mainly due to the higher saturated hydraulic conductivity, soil saturated water content, field capacity, and soil available water content, which led to an increase in the available water storage in the 0–100 cm soil profile by 29–48 mm. Furthermore, the MM also improved soil organic matter, porosity, root length density, and root weight density and reduced the soil bulk density, which are beneficial for the improvement of the above soil hydraulic properties. Therefore, it is a practical way to ensure high yield and high efficiency of crops in dryland by improving water storage capacity and the available water in the soil, which can be profoundly regulated by agronomic management. [ABSTRACT FROM AUTHOR]

Conservation tillage methods, including straw return (SR) and no tillage (NT), are widely used to improve the soil organic carbon (SOC) content and crop yield. However, applying SR or NT separately has become a common practice for farmers producing different crops or those in different regions. Evaluating the effects of SR or NT on the SOC content, carbon emissions, and crop yield are important for guiding the correct application of conservation tillage and promoting sustainable agricultural development. Therefore, we conducted a meta-analysis based on 1014 sets of data obtained in China to assess the effects of SR and NT on the SOC content, carbon emissions, and crop yield. Compared with no straw return, SR increased the SOC content and crop yield by 10% and 8.6%, respectively, but with no significant impact on carbon emissions. Compared with conventional tillage, NT increased the SOC content by 2.9% and reduced the carbon emissions and crop yield by 18% and 3.9%, respectively. We also found that SR combined with NT had an additive effect, where the combination improved SOC more than applying SR or NT alone. If applying SR or NT alone, the specific climatic conditions, soil characteristics, and field management strategies need to be considered to maximize SOC. In particular, SR should be used in limited hydrothermal conditions (low temperature or low precipitation) and areas where rice–wheat rotation is implemented. NT can be used under any climate conditions, but it can effectively increase the SOC content in continuous wheat cropping areas. [ABSTRACT FROM AUTHOR]

The understanding of the spatial distribution of soil organic carbon (SOC) and its influencing factors is crucial for comprehending the global carbon cycle. However, the impact of soil geochemical and climatic conditions on SOC remains limited, particularly in dryland farming areas. In this study, we aimed to enhance the understanding of the factors influencing the distribution of SOC in the drylands of the Songliao Plain, Northeast China. A dataset comprising 35,188 measured soil samples was used to map the SOC distribution in the region. Multiple linear regression (MLR) and random forest models (RFM) were employed to assess the importance of driving indicators for SOC. We also carried out partial correlation and path analyses to further investigate the relationship between climate and geochemistry. The SOC content in dryland soils of the Songliao Plain ranged from 0.05% to 11.63%, with a mean value of 1.47% ± 0.90%. There was a notable increasing trend in SOC content from the southwest to the northeast regions. The results of MLR and RFM revealed that temperature was the most critical factor, demonstrating a significant negative correlation with SOC content. Additionally, iron oxide was the most important soil geochemical indicator affecting SOC variability. Our research further suggested that climate may exert an indirect influence on SOC concentrations through its effect on geochemical properties of soil. These insights highlight the importance of considering both the direct and indirect impact of climate in predicting the SOC under future climate change. [ABSTRACT FROM AUTHOR]

Iron-metamorphic soils of normal moistening were studied in the middle taiga subzone of Karelia. The examined sites comprise arable land, hayfield, 15- and 75-year-old naturally reforested pine stands on former farmland, and 100-year-old pine forest as a control. The effects of different land use types on soil morphology and the main chemical and microbiological characteristics of the upper horizons were analyzed. The stocks of organic carbon (Corg) and microbial biomass carbon (Cmic) in 0–100-cm soil layer and the structure of carbon pools in these sites were studied. Characteristic of the soils of all sites are a uniform accumulative type of carbon distribution and similar values of C/N ratio (16–18). The soils display a low natural fertility and unfavorable agrochemical characteristics, which are considerably improvable by agricultural management. Arable land has the highest Corg (4.9%) and Ntot (0.3%) contents at a low bulk density and neutral pH. The soil under the young forest displays the highest Cmic content (419 mg C/kg); soils of arable land and hayfield, 209–211 mg C/kg; and that under mature forest stands, the minimum (144–175 mg C/kg). The stock of microbial biomass carbon in the 0–100-cm soil layer ranges from 76.5 to 132.4 g C/m2 in the studied land use types and the Cmic content in the forest litter amounts to 12.7–27.4 g C/m2. In the 0–100-cm layer, Corg stock is the maximum in arable land, amounting to 272 t C/ha, and decreases from hayfield to mature forest stand (98 to 39 t C/ha, respectively). The total ecosystem carbon stock is the maximum in arable land (275 t C/ha), which exceeds the stock in mature forest stands (206–221 t C/ha). The Corg stocks in young forest and hayfield are 105–115 t C/ha. [ABSTRACT FROM AUTHOR]

Semi-arid agroecosystems are crucial for food security and ecosystem services, but land degradation threatens their sustainability. This study assessed land degradation neutrality (LDN) in a semi-arid agroecosystem of Matabeleland North Province, Zimbabwe, leveraging trends.earth within QGIS and data from the European Space Agency Climate Change Initiative (1992–2020). We analysed land use/land cover (LULC), soil organic carbon (SOC), and land productivity to identify areas of degradation and stability. Additionally, we simulated 2050 land-use/land-cover maps using a cellular automata model within a GIS framework assuming a business-as-usual scenario. The model considered the 2015 LULC map as a baseline along with environmental variables such as the digital elevation model and slope. While historical trends (1992–2020) showed a decrease in bare areas (-71%) and an increase in settlements (+ 163%), cellular automata modeling predicted a concerning future trajectory with further expansion of bare land (+ 238%) and settlements (+ 72%) by 2050, alongside a decline in water bodies (-23%) and forests (-3.5%). Notably, around 26.5% of the land exhibited degradation, often linked to low SOC levels in croplands, while 59.55% remained stable over the study period. However, caution is necessary as increases in greenness may not always reflect positive restoration. Land cover transitions, particularly the conversion of forests to grasslands and settlements, emerged as potential drivers of degradation, likely leading to ecosystem service loss, habitat fragmentation, and potentially exacerbating the impacts of climate change. These findings highlight the urgent need for targeted restoration and land management strategies focused on improving SOC levels in croplands and conserving vital forest and grassland ecosystems to achieve LDN in this semi-arid region. Further research is needed to quantify specific degradation drivers, assess the effectiveness of intervention strategies, and explore the socio-economic dimensions of land degradation and LDN efforts. [ABSTRACT FROM AUTHOR]

Climate-smart agriculture (CSA) has become a central element in driving the greening agenda in agriculture. An in-depth exploration of global progress of CSA research globally can help to improve the level of understanding and assessment of the field by both academics and practitioners alike. Based on the Web of Science database resources, this paper analyzed the international CSA research hotspots using a bibliometric approach, based on 814 papers published on CSA topics between 2014-01-01 and 2023-08-11. The main findings were as follows: (1) since 2018, there had been a notable surge in the publication of CSA-related papers and subsequent citations. The core of CSA research predominantly revolved around environmental science, sustainability studies, agronomy, and interdisciplinary fields; (2) Keyword hotspots mainly included climate-smart agriculture, climate change, adoption, conservation agriculture, management, food security, mitigation, and farmers, etc.; (3) The research hotspots mainly included conservation agriculture, the impact and quantification of CSA on soil organic carbon, the effects of CSA application in different regions, the key factors affecting the adoption of CSA by farmers, and CSA-related decision support, which revealed that the effects of CSA implementation vary in different countries and regions, and that the key factors for the adoption of CSA by farmers were diversified, which suggested that policymakers must consider diversified factors comprehensively when designing and implementing CSA strategies to ensure the effective promotion and localized application of CSA measures across the globe. This suggested that policymakers should consider the diversity of factors when designing and implementing CSA strategies to ensure the effective promotion and localized application of CSA measures in all parts of the world; (4) The 25 references with a surge in citations from 2014−2023 were mainly focused on the core topics of conservation agriculture, the application and challenges of CSA, as well as the impacts of climate change on agriculture and coping strategies. [ABSTRACT FROM AUTHOR]

This study aimed to assess the potential of soil organic carbon (SOC) production through organic amendments. SOC sequestration would help to achieve the net-zero emissions targets set by the Intergovernmental Panel on Climate Change (IPCC). Given the urgency to reduce greenhouse gas emissions, traditional methods that estimate SOC over 100 years must be revised. Hence, a novel fate transport numerical model was developed to forecast SOC levels relevant to individual countries' net-zero targets in various time frames. The simulation results revealed that most countries had sufficient organic amendment to mitigate the CO2 emission of that country for a year if the organic amendment was applied on 20% of the arable land. However, if a significant fraction of the total CO2 emissions needs to be mitigated before reaching the net zero target, the requirements of organic amendments need to be increased several folds. All the available agricultural land should also be brought under the organic amendment regime. Later, the dynamic LCA approach was undertaken for estimating Global Warming (GWP) from land-applied organic residue. It was observed that, depending on the dynamic LCA model, the estimated GWP was different. However, the estimated dynamic GWP was very close to the residual SOC calculated through the fate transport model. The mass of organic residues generated from a biorefinery was examined by employing a waste biorefinery model to explore further the routes of acquiring additional organic amendment. Simulated results showed that while a waste biorefinery could not provide additional organic residue compared to the original organic waste input, it was highly efficient for nutrient recovery and its uses. This study demonstrated that organic amendment-based carbon sequestration adequately mitigated residual GHG at the net-zero target. [ABSTRACT FROM AUTHOR]

[Objective] The aims of this study are to explore the effects of different economic forest planting modes on soil water physical properties and soil nutrients in central and southern Shandong, and to provide a basis for screening and planting management of soil and water conservation economic forest planting modes in this area. [Methods] Four kinds of economic forest planting modes in Menglianggu small watershed of Mengyin County, Linyi City, were selected as the research objects, including A. persica (TS). C. pinnati fida (SZ). M. pumila P. pseudocerasus (PY). and C. mollissima + 2. bungeunum (BH), with wasteland (CK) as the control. The water physical indexes such as soil bulk density, porosity and water storage capacity, and the nutrient indexes such as soil organic carbon, total nitrogen, total phosphorus and available nutrients were measured and analyzed. The soil improvement effect was comprehensively evaluated hy Principal component analysis and fuzzy mathematics membership function method. [Results] (1) Economic forest planting could improve soil porosity and water storage performance. Compared with CK, the four economic forest. planting patterns could reduce soil bulk density by 7.3%~22.1%, increase capillary porosity by 14.2%~ 42.0%, and increase soil maximum water storage by 16.5%~43.8%. The soil water holding capacity decressed in the order, TS>PY BH>SZ>CK. In addition to PY. other economic forest planting patterns could effectively increase soil storage and storage precipitation, showing BH TS SZ>CK. The effect of economic forest planting on the storage precipitation and effective storage capacity of 0-20 cm soil layer was more obvious. Compared with 0-20 cm soil layer the porosity and maximum water storage capacity of 20 40 cm soil layer decreased, and the change range of TS was the smallest. (2) Economic forest planting could improve soil organic carbon and available nutrients. Compared with CK the four economic forest planting patterns could increase soil organic carbon by 6.9%~270.4%, which was expressed as TS>PY BHSZ CK: the contents of total nitrogen and total phosphorus in soil decreased in the oder, TSPY>BH>SZ> CK. The effect of economic forest planting on the nutrient content of 0-20 cm soil layer was more obvious. Compared with 0-20 cm soil layer the nutrient content of 2040 cm soil layer decreased. (3) The indicators reflecting the soil improvement effect of economic forest planting modes could be summarized into three categories. The first was soil capillary water holding characteristics and nutrient characteristics, the second was soil water storage characteristics and the third was soil non-capillary water holding. characteristics. [Conclusion] The cotoprehensive evaluation of soil improvement effect of different economic forest planting modes is, A. persica C. mollissima Z. bungeanum M. pumila + P. pseudocerasus>С. pinnatifida wasteland. Compared with grassland economic forest planting can significantly improve the physical properties of soil moisture and improve soil nutrient performance, but the soil improvement effect varies greatly with different planting modes. In the arid and barren mountainous areas of central and southern Shandong, the planting mode of A. persica has the best effect on soil improvement, followed by C. mollissimaZ. bungeunum and C. pinnatifidu is relatively poor. [ABSTRACT FROM AUTHOR]

[Objective] The aim of this study is to explore the relationship between soil organic carbon content and soil physicochemical factors of different forest types in southeastern Guizhou Province, China. [Methods] The pure Pinus massoniana forest, pure Cunninghamia lanceolata forest, coniferous mixed forest, broad-leaved mixed forest, and coniferous broad-leaved mixed forest were selected in Tianzhu State owned Forest Farm. The standard plot survey method was used to set up sample plots for five types of forests. Five point sampling method was used to collect soil samples from 0-20 cm, 20-40 cm, and 40-60 cm layers of each forest, and soil organic total carbon, soil pH, soil moisture content, soil bulk density, and soil gravel content were measured for each forest type, nitrogen, phosphorus, potassium and other physical and chemical indicators. Person correlation analysis between soil organic carbon and soil physical and chemical properties were conducted. [Results (1) The total organic carbon content of soil pure Pinus massoniana fores ranged from 22.25 to 42.08 g/kg, pure Cunninghamia lanceolata forest ranged from 30.12 to 50.33 g/kg, coniferous mixed fores ranged from 22.93 to 48.17 g/kg, broad-leaved mixed forest ranged from 24.01 to 67.68 g/kg, and soil coniferous broad-leaved mixed forest ranged from 32.99 to 92.36 g/kg. Overall, coniferous broad-leaved mixed forest soil had the highest organic carbon content, and all forest types exhibited surface enrichment characteristics. (2) The pure Pinus massoniana forest was positively correlated with soil total nitrogen and hydrolyzed nitrogen, while the pure Chinese fir forest was negatively correlated with soil total nitrogen and hydrolyzed nitrogen. The mixed coniferous forest was negatively correlated with soil pH, soil moisture, total nitrogen, and total potassium content. The broad-leaved forest was positively correlated with soil pH and total potassium content, while the mixed coniferous and broad- leaved forest was positively correlated with soil moisture, total nitrogen, total phosphorus, and total potassium content. (3) The organic carbon content of pure Pinus massoniana fores soil was mainly affected by the content of hydrolyzed nitrogen, pure Cunninghamia lanceolata forest and coniferous mixed fores were mainly affected by the content of total nitrogen, broad-leaved mixed forest was mainly affected by the soil pH, coniferous broad-leaved mixed forest was the main factor of soil moisture, total phosphorus, hydrolyzed nitrogen and total nitrogen, and the degree of influence is manifested by the order: water content > total phosphorus hydrolyzed nitrogen total nitrogen. [Conclusion] The content of soil organic carbon is significantly influenced by forest type and soil physicochemical properties, and constructing a mixed forest with needle and broad-leaved trees is more conducive to the accumulation of soil organic carbon. [ABSTRACT FROM AUTHOR]

[Objective] The aim of this study is to explore the accuracy and applicability of different machine learning models for predicting the spatial distribution of surface soil organic carbon density (SOCD) with limited samples, which can provide a references for the study of watershed scale carbon pool in the Chinese Loess Plateau. [Methods] In this study, we compared the accuracy and stability of the predicted SOCD in topsoil (0-20 cm) by four machine learning models, namely Multiple Linear Stepwise Regression (SR), Random Forest (RF), Extreme Gradient Boosting (XGB) and Support Vector Machine (SVM), based on the limited measured samples in a sub-watershed of Yanhe River in the Chinese Loess Plateau. [Results] (1) Under the condition of limited samples, all models successfully and appropriately predicte the spatial distribution of SOCD, among which the SVM model has the best model performance, and the average RMSE, R² and MAE of 50 predictions is 0.74. 0.43 and 0.64, respectively. (2) The average SOCD of different land use types are consistent between measured and predicted values but shows significant difference among land use types. SOCD decreases in the order: shrubland forestland > grassland > cropland. The total organic carbon of cultivated land in the study area is 2.39×106t (0-20 cm). (3) The evaluation of feature importance shows that terrain factors, NDVI max, near-infrared surface reflectance (B5) and Brightness index have significant contributions to the accuracy of predictions. [Conclusion] Under the condition of limited samples, the machine learning model combined with controlling features can be effectively applied to the prediction of the spatial distribution of topsoil SOCD at the watershed scale in the Chinese Loess Plateau. [ABSTRACT FROM AUTHOR]

Biochar is a carbon-rich product obtained by biomass pyrolysis and is considered as a means of carbon sequestration. However, there is limited knowledge regarding responses of soil respiration and C-cycle enzyme activities to BC in a calcareous soil. In this study, different biochar AS, TS, PP, CS were applied to the soil at different rates (0.5, 1.0, and 1.5%) The highest increase in soil organic C content was observed in the TS treatment, while the AS treatment caused a slight increase of soil organic C. The highest MBC content was recorded in AS treatment and the lowest was observed in TS. The highest CO2-C emission was recorded in the TS treatment. In contrast, the lowest CO2-C emission was observed in the PP treatment due to its high recalcitrant C content and was attributed to a positive priming effect, stabilizing BC mineralization to improve the soil. The highest β-galactosidase enzyme activity was observed in the CS treatment and the lowest activity was observed in AS. The highest change in β-glycosidase enzyme activity was observed of PP treatment and the lowest was in AS biochar application. Thus, TS treatment is recommended to increase the organic C content of soils, and the PP biochar can be used to reduce CO2-C emission. The TS, PP, and CS can be applied to increase enzyme activities. The study clearly shows that the addition of BC to arid soils may have a high potential to improve soil enzyme activities and subsequent carbon sequestration and biochemical cycles. [ABSTRACT FROM AUTHOR]

The study area is Karabük province, and the research topic is to examine the influence of soil-related variables on soil organic carbon in Karabük province. The aim of the study is to determine the relationship between digital soil mapping and the correlation analysis of soil variables that affect the carbon stock stored by the soil. In the study, data from SoilGrids was gathered using Google Earth Engine (GEE) machine learning methods. The JavaScript coding language was used to generate maps of SoilGrids data in GEE. These spatial data were processed using Geographic Information Systems software, and multiple linear regression analysis was performed using the "IBM SPSS 20.0″ program. Clay, sand, silt, pH (in water), organic carbon density, mass density, coarse fractions, cation exchange capacity (CEC), and nitrogen were considered as soil variables. According to the results obtained, the pH of the surface soils (0–5 cm) of the study area was 58–7: clay g/kg; 104–400 g/kg; sand; 214–460; silt; 331–510 g/kg; organic carbon density: 380–562 dg/dm3; nitrogen density: 2 920–7 683 cg/kg; mass density: 93.00–136.00 g/kg; coarse particles: 55–239 (Per10000); CEC: 215–348 mmol/kg; and SOC values varied between 286–374 dg/kg. Soil organic carbon (SOC) stock amounts varied between 286 and 374 dg/kg in surface (0–5 cm) soils. As a consequence of the studies, it was revealed that nitrogen had the strongest link with SOC, whereas clay had the lowest relationship. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) is an important component of soil and plays a crucial role in addressing climate change. As a key component of soil organic matter, SOC directly impacts soil fertility, water retention, nutrient cycling, and overall soil health. The determination of SOC concentrations in soil often relies on costly physical sampling and chemical analysis. The aim of this research was to build a predictive model of SOC using satellite imagery of Landsat 8 OLI/TIRS over an agricultural area (Oued El Alleug) in the north of Algeria. The statistical correlations between the spectral bands (B2 and B6) and chemically measured SOC concentrations showed that it is possible to predict spatially the SOC concentrations. The results also showed that the topographic variables are not determinant in the spatial prediction of SOC concentrations. The predicted model showed an acceptable performance with a coefficient of determination (R2) = 0.7 and a root mean square error (RMSE) = 7.08 g/kg during the validation phase. The results of this study are important, as they will facilitate decision-making in soil conservation practices and enhance land management, especially in areas facing increasing agricultural and environmental pressures. [ABSTRACT FROM AUTHOR]

Perennial vegetation in farmlands can mitigate anthropogenic greenhouse gases (GHG) by capturing atmospheric carbon and storing it in the soil for extended periods. The objective of this study was to quantify soil organic carbon (SOC) concentrations and stocks under tree buffer (TB), grass buffer (GB), grass waterways (WW) and crop field (CS, corn-soybean rotation) to evaluate the significance of conservation measures in C sequestration projects. Soil samples were collected up to 1 m depth at upper, middle, and lower landscape positions from 26-year-old TB, GB, and WW in a watershed. The SOC concentration decreased with increasing soil depth for all four land uses. However, as expected, bulk density increased with increasing soil depth for all four land uses. It was highest for the CS land use. In 2023, for the depth of 0–10 cm, SOC increased by +0.63, +1.06, +1.37 and +1.63% in CS, GB, TB, and WW, respectively, since the land uses were established 26 years ago. Land uses had greater impacts on SOC stock in the top 50 cm depth, with WW (113.5 ± 12.9 Mg ha−1), TB (106 ± 14.5 Mg ha−1), and GB (102.4 ± 11.6 Mg ha−1) compared to CS (90.9 ± 10.2 Mg ha−1). However, at watershed level, with ~ 10% cover by TB or GB areas and the rest under CS, SOC stock up to 50 cm depth was respectively 91.6 and 91.2 Mg ha−1 compared to 90 Mg ha−1 by CS alone—1.3 to 1.8% increase. This is a significant increase in soil organic carbon across the landscape, which was realized with the conservation practices and agroforestry, while also playing a crucial role in protecting surface runoff in the landscape. Future studies may consider valuation of the overall ecosystem services due to the land uses (conservation measures) and the trees by considering optimization of incorporating such technologies in the farming systems to reduce negative trade-offs. [ABSTRACT FROM AUTHOR]

Wildfire strongly influences permafrost environment and soil organic carbon (SOC) pool. In this study, we reviewed the effects of fire severity, time after a fire, and frequency on SOC in boreal permafrost regions. This review highlighted several key points: the effect of wildfires on SOC increased with an increase of fire severity, and the amount of vegetation returned and surface organic matter replenished was less in a short term, which resulted in a significantly lower SOC content compared to that of before the fire. Within a short period after fire, the SOC in near‐surface permafrost and the active layer decreased significantly due to the loss of above ground biomass, permafrost thaw, and increased microbial decomposition; as the years pass after a fire, the SOC gradually accumulates due to the contributions of litter layer accumulation and rooting systems from different stages of succession. The increase in fire frequency accelerated permafrost thawing and the formation of thermokarst, resulting in the rapid release of a large amount of soil carbon and reduced SOC storage. Therefore, the study on the effects of wildfires on SOC in the boreal permafrost region is of great significance to understanding and quantifying the carbon balance of the ecosystem. [ABSTRACT FROM AUTHOR]

The terrestrial environment generally serves as an important carbon pool. This study mainly assessed the properties and carbon storage capabilities of soils from different urban land uses. Soil samples from roads/highways, parks, institutional areas, and constructed wetlands were collected to assess the effects of soil sealing on the characteristics and carbon content of urban soils. Soil sealing and compaction greatly influenced urban soil properties by altering the mass-balance, thereby resulting in a disproportionate amount of inflow and outflow of compounds in the soil strata. Using the Walkley-Black and loss-on-ignition (LOI) methods of soil organic carbon (SOC) analysis demonstrated that LOI-based analysis yielded up to 26 times higher SOC values than the wet-oxidation method due to the high weight losses prompted by the volatilization of hygroscopic and structural water and thermal decomposition of carbonate-containing minerals. Further analyses indicated that open soils contain 5% to 78% higher percentage of organic carbon as compared with their sealed counterparts and top soil layers tend to have higher amounts of SOC due to the continuous deposition of carbon-containing compounds from external sources. Generally, the results of this inquiry can serve as a baseline for formulating strategies to augment pedologic carbon stocks in urban environments. [ABSTRACT FROM AUTHOR]

Biochar application is an effective way to improve soil organic carbon (SOC) content and ensure food security. However, there were differences in SOC content following biochar application under different conditions. We collected 637 paired comparisons from 101 articles to determine the following: (1) the average effect of biochar application on SOC content and (2) the response of SOC content to different soil nutrient contents, climate zones and cropping systems following biochar application. The results showed that the soil available phosphorus (P) content and soil available potassium (K) content reached the highest level in the category of <10 mg kg−1 and >150 mg kg−1, respectively. Soil total P content subgroups achieved maximum increase in the intermediate category. The Cw zone (temperate, without dry season) obtained the maximum level of SOC content. Compared with plough tillage, rotary tillage presented significantly higher SOC content. Therefore, low available P and K contents, moderate soil total N and P contents, rotary tillage and the Cw zone were more effective in increasing SOC content. Furthermore, the results of a random forest algorithm showed that soil nutrient contents were the most important variables. This study provided a scientific basis for SOC sequestration and improving soil fertility. [ABSTRACT FROM AUTHOR]

Cropland (CRL) abandonment is a worldwide phenomenon of land use change with significant impacts on agro‐ecosystems. This research attempts to deepen the analysis of the positive and negative effects arising by focusing on the changes in soil properties and the amount and composition of soil particles detached after several periods of rainfall and the resulting exported sediment that occurs in abandoned areas with natural revegetation compared to CRL. The study was carried out in an agroforestry catchment with a temperate climate, on which CRL and abandoned land with natural vegetation were compared. The soil was sampled along two representative hillslopes integrating elements of the landscape and land use/land covers. Sediments were collected after seven periods in which flood events were recorded during the period July 2016 to December 2017, using artificial‐lawn mats. Soil and sediment composition (texture, soil organic carbon [SOC] and nutrients [total nitrogen and total phosphorous]) under both land uses were assessed and compared and related to rainfall characteristics using principal component analysis. Nutrient enrichment factors in the sediments compared to soils were also evaluated. The results highlight that after abandonment, SOC increased significantly, reaching contents almost three times higher than in CRL. Consequently, soil erodibility decreased, resulting in substantially lower sediment generation after erosive rainfall events. On average, sediment generation was three times lower in abandoned areas than in CRL, despite their steeper slopes. Soil total nitrogen also increased on abandoned lands, reaching values about twice as high as those in CRL. However, total phosphorous content was almost twice as high in CRL than in abandoned land posing a potential risk for water due to higher erosion rates recorded in CRL. The results confirmed the association of phosphorous with smaller particles and also demonstrated the total phosphorous‐SOC link in abandoned land. Furthermore, the effect of rainfall intensity on phosphorous mobilisation was confirmed, whilst nitrogen losses were mainly related to the total amount of rainfall recorded. In a scenario of increasing extreme precipitation, both total amount and increased precipitation intensity may exacerbate water pollution problems following nutrient loss in cultivated areas. This research contributes to identifying the impacts on agroforestry systems within the current context of converting natural areas into cultivated land, whilst in other regions revegetated natural areas are developed from abandoned agricultural land. [ABSTRACT FROM AUTHOR]

Evaluating the impact of vegetation types and reclamation methods on soil organic carbon and nitrogen in carboniferous spoil heaps is critical for selecting the best vegetation type and reclamation method to improve ecosystem services in a changing climate. This paper presents the relationship between vegetation types (woodland, forbland, and grassland) and reclamation techniques (barren rock, topsoil application, succession, and cultivation) on soil organic carbon (SOC) and total nitrogen (TN) in developing soils on carboniferous rocks in coal mine heaps. Soil samples were collected from the litter layer (Oi + Oe) and the A horizons (0–10 cm). The results revealed that vegetation types and reclamation methods significantly affected SOC and TN stocks. Woodland exhibited higher SOC and TN in the Oi + Oe horizons than other vegetation types. Topsoil application and cultivation resulted in the highest SOC and TN stocks in the A horizons (0–10 cm) under woodland and forbland compared to succession on bare carboniferous rock. In grassland, there was no significant difference in SOC stock under topsoil application and cultivation; however, significantly higher TN stock was observed in the 0–10 cm areas with topsoil application compared to succession on bare carboniferous rock. Based on the results, topsoil application is recommended to improve SOC if the mining site is restored using woodland. Conversely, grassland exhibits a similar amount of SOC stock with or without topsoil application. Considering the difficulty of obtaining topsoil, we suggest that grasses are optimal for SOC stock in the studied mining sites, followed by forbs. [ABSTRACT FROM AUTHOR]

Purpose: Incorporating rice straw into upland has been adopted as a strategy to increase crop productivity and decrease poisoning to rice from reducing substances accumulation as well as mitigate methane emission from paddy fields in South China. However, the mechanism underlying long-term ex situ incorporation of rice straw in upland on soil organic carbon (SOC) and crop yields through microbial metabolism remains unclear. Materials and methods: Hence, a field experiment was established to investigate the response mechanism of SOC and crop yields underlying microbe-mediated carbon dynamics with nutrient stoichiometry by ex situ incorporation of rice straw in upland. Results and discussion: The results showed that the treatment of cropping with chemical fertilizers plus rice straw (SCF) had the highest SOC accumulation rate (0.14 ± 0.03 g C kg−1 yr−1) during the 22-year experimental period. The mean yields of rapeseed and sweet potato were increased by 5.0% and 4.7% in the SCF treatment, correspondingly, compared with the treatment of cropping with chemical fertilizers (CF). Additionally, based on ecoenzymatic stoichiometry, soil microorganisms were found to be co-limited by carbon and phosphorus, which was aggravated by the decrease of soil available nutrients. The SCF treatment exhibited a higher soil microbiomass, resulting in an increased secretion of ecoenzymatic activities to mediate stoichiometric imbalance and mitigate nutrient competition between plant and microbial nutrient limitations. The findings revealed a significant association between stoichiometric imbalance and both SOC and crop yields, respectively. Conclusions: Therefore, our study indicated that long-term ex situ incorporation of rice straw in upland could be adopted as an effective agricultural management strategy to improve SOC and crop yields. [ABSTRACT FROM AUTHOR]

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Despite its crucial role in flood defense for downstream regions, the catastrophic breach of the Kakhovka Dam on June 6, 2023, along the Dnipro River in Ukraine caused extensive flooding and damage both upstream and downstream. In addition, the subsequent significant drying up of the dam reservoir poses serious challenges, including hindered electricity generation, compromised flood control measures, and disrupted aquatic ecosystems. This study aims to address knowledge gaps related to the event by employing multi-temporal change detection of pre- and post-event Sentinel-1 synthetic aperture radar (SAR) imagery, analyzed using the Google Earth Engine (GEE) platform, to map flood extent and impacts. Furthermore, we assessed the impacts of dam breaches on soil organic carbon (SOC) sequestration potential in both the drying reservoir region upstream and the flooded areas downstream. The results estimated the total area of the flood extent to be approximately 379.41 km2, with an overall accuracy (OA) of 94% and a Kappa index (K) of 0.89. Quantitative analysis revealed that 81.15 km2 of urban areas, 82.59 km2 of agricultural lands, and 215.56 km2 of herbaceous wetlands were submerged by floodwaters. Both flooding and reservoir drawdown from dam collapses can significantly affect soil organic carbon (SOC) sequestration rates in affected soils. The quantification of post-disaster impacts underscores the pressing need for restoration practices and sustainable management efforts to lessen the environmental impacts and enhance the recovery of the affected regions. [ABSTRACT FROM AUTHOR]

Urban forests are crucial components of cities, serving as vital 'green lungs' that embody urban civilization and sustainability. Despite their significance in maintaining the urban environment and ecological functions, management practices for urban forests can be unreasonable at times. This study investigated the impact of two common practices, litter removal and biochar application, on soil properties in an urban forest in Changsha city, China. The aim was to understand how these practices affect soil carbon, nutrients, and microbial activity in urban settings. The results showed that soil water content (SWC), pH, available phosphorus (AP), and soil microbial biomass carbon (SMBC) were significantly reduced in areas where litter was removed compared to areas where litter was retained. Conversely, biochar application led to a significant increase in SWC, pH, AP, and SMBC. The treatment alone had no significant effects on total nitrogen (TN), soil organic carbon (SOC), and soluble soil organic carbon (SSOC) in the examined urban forests. However, the SOC and SSOC contents significantly increased over time with biochar application. Our results demonstrated that the influences of litter removal and biochar application on soil property were attributed to the regulation of AP and SMBC in the studied urban forests. This study provides a scientific basis and reference for understanding the sustainable management of urban environments and guiding future conservation efforts in urban greening spaces. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Food, feed, and fiber production needs to increase to support demands of the growing population in Sub‐Saharan Africa (SSA), while soil fertility continues to decline. Intercropping, the cultivation of two or more crop species on the same field, can provide yield benefits and is suggested to positively affect soil organic carbon (C) and nitrogen (N) stocks. This study uses the biogeochemical model system LandscapeDNDC with the objective to (a) represent maize‐legume intercropping systems in different bioregions in SSA by simultaneously simulating both crops and their interactions and (b) assess long‐term (20 years) impacts of intercropping under varying mineral fertilizer inputs (0–150 kg N ha−1 yr−1) on productivity as well as soil organic C and N stocks. We test LandscapeDNDC on 82 field data sets (site‐year‐treatment combinations) from 18 sites to represent yields and soil C/N dynamics of maize‐legume intercropping systems. Using the model for long‐term scenario simulations showed that intercropping allows to sustain productivity and to improve or maintain SOC stock in low or zero fertilizer systems if all residues are returned to the soil. In contrast, for sole‐cropped maize systems, a decline in SOC stocks was simulated unless a minimum of 35 kg N ha−1 yr−1 of fertilizer was applied at full residue return. We conclude that intercropping using legumes alongside sufficient residue return allows for stabilizing long‐term yields while avoiding SOC losses even with low fertilizer N inputs. Overall, our study confirms the potential of intercropping as a sustainable agricultural practice that could significantly contribute to food security in SSA. Key Points: Intercropping alongside sufficient residue return allows for stabilizing long‐term yieldsIntercropping allows to maintain SOC stocks in low or zero fertilizer systems if all residues are returned to the soilIntercropping reduces the amount of N fertilizer needed to maintain soil N stocks [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ecology & Rural Environment is the property of Journal of Ecology & Rural Environment Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Polyethylene mulching film, which is widely utilized in arid and semi-arid agriculture, leaves residual pollution. A novel approach to addressing this issue is microbial degradation. To screen the strains that degrade polyethylene efficiently and clarify the effect of degrading strains on the turnover of soil organic carbon, a polyethylene-degrading fungus PF2, identified as Trichoderma asperellum, was isolated from long-time polyethylene-covered soil. Strain PF2 induced surface damage and ether bonds, ketone groups and other active functional groups in polyethylene, with 4.15% weight loss after 30 days, where laccase plays a key role in the degradation of polyethylene. When applied to soil, the Trichoderma-to-soil weight ratios were the following: B1: 1:100; B2: 1:200; B3: 1:300 and B4: 1:400. Trichoderma asperellum significantly increased the cumulative CO2 mineralization and soil organic carbon mineralization in the B1 and B2 treatments compared with the control (B0). The treatments B1, B3 and B4 increased the stable organic carbon content in soil. An increase in the soil organic carbon content was observed with the application of Trichoderma asperellum, ranging from 27.87% to 58.38%. A positive correlation between CO2 emissions and soil organic carbon was observed, with the soil carbon pool management index (CPMI) being most correlated with active organic carbon. Trichoderma treatments improved the CPMI, with B3 showing the most favorable carbon retention value. Thus, Trichoderma asperellum not only degrades polyethylene but also contributes to carbon sequestration and soil fertility when applied appropriately. [ABSTRACT FROM AUTHOR]

The production of fruit tree seedlings generates waste wood biomass, which results from the pruning of budded rootstocks in the first year of the two-year production cycle. This study proposes a new method of managing this biomass by recycling the wood chips (2, 3 and 5 t ha−1) back into the soil. The impact of different wood chip doses on selected physicochemical soil properties after the production process (especially soil organic carbon content (SOC), as well as the quantity and quality of the produced Malus domestica fruit tree seedlings, was determined. The recycling of waste biomass contributed to enriching the soil with additional components, mainly organic carbon with the potential for biotransformation into humic substances. The applied doses of wood chips, in amounts of 2, 3, and 5 t ha−1, resulted in an increase in SOC content compared to the control by 21.5%, 22.5%, and 35.8%, respectively. Additionally, the recycling of waste biomass introduced other compounds important for plant growth and development into the soil, particularly iron, zinc, magnesium, and manganese. It should be noted that the proposed method of managing waste biomass generated during the apple tree seedling production stage resulted in reduced production costs while maintaining high production indices. [ABSTRACT FROM AUTHOR]

Soil carbon sequestration is an important process of the terrestrial carbon cycle, and even slight changes in soil carbon will trigger drastic variations in the global carbon pool. In this study, we used the CiteSpace software to analyze the development of research on soil organic carbon (SOC) and its current status from various perspectives, with the goal of revealing research hotspots and trends of SOC. A total of 3909 studies published between 2014 and 2023 were included in the analysis. Results show that China and the USA lead with a significant number of publications on SOC, which underscores their considerable interest in the subject. France and the USA exhibit a very high international influence in this field, with their intermediary centrality reaching up to 0.3 and 0.21, respectively. Among institutions, the Chinese Academy of Sciences is the largest contributor in terms of the number of publications, with a high centrality of 0.09, indicating this institution has built close collaboration and significant influence in this field. Kuzyakov Yakov achieved the highest publication record, with Lal Rattan sharing the second position. The hotspots in SOC can be summarized into the following aspects: conservation tillage, carbon sequestration, microbial biomass, and driving forces. The research focus has gradually shifted from macroscopic trends to explanations based on micro-level biological dynamics. Driving forces such as soil type, land use, and environmental conditions have a significant impact on the quantity, turnover, and spatiotemporal distribution of SOC. We highlighted that more attention should be paid to the mechanism of SOC transformation and stabilization, which is essential for developing more precise models of carbon cycling in the soil and for formulating effective strategies to maintain sustainable agriculture and mitigate climate change. [ABSTRACT FROM AUTHOR]

Our study from an ongoing research experiment initiated in Rabi 1967 at the Research Farm of CCS Haryana Agricultural University, Haryana, India, reports that during the 51st wheat cycle in pearl millet-wheat sequence, adding FYM in both seasons significantly impacted various soil parameters at different wheat growth stages compared to the rabi season. The application of 15 t of FYM ha−1 resulted in a considerable increase in dissolved organic carbon content (9.1–11.2%), available P (9.7–12.1%), and available S (12.6–17.1%), DHA levels by 7.3–22.0%, urease activity (10.1 and 17.0%), β-Glucosidase activity (6.2–8.4%), and APA activity (5.2–10.6%), compared to 10 t FYM ha−1. Application of N120 exhibited a considerable improvement in DHA (11.0–23.2%), β-Glucosidase (9.4–19.2%), urease (13.3–28.3%), and APA (3.3–6.2%) activity compared to control (N0). At stage 3, the box plot revealed that 50% of the available N, P, and S values varied from 223.1 to 287.9 kg ha−1, 53.0 to 98.2 kg ha−1, and 50.0 to 97.6 kg ha−1, respectively. Principal component analysis, with PC1 explaining 94.7% and PC2 explaining 3.15% of the overall variability, and SOC had a polynomial relationship with soil characteristics (R2 = 0.89 to 0.99). Applying FYM15 × N120 treatment during both seasons proved beneficial in sustaining the health of sandy loam soil in North-West India. [ABSTRACT FROM AUTHOR]