Enhance Soil Carbon Sequestration Research Articles

Environmental impact of modern agricultural practices: Strategies for reducing carbon footprint and promoting conservation

Modern agricultural practices have significantly transformed food production, leading to increased efficiency and productivity. However, these advancements have also had notable environmental impacts, particularly concerning carbon emissions and resource depletion. This study explores the environmental impact of contemporary agricultural practices, emphasizing the need for strategies to mitigate carbon footprints and enhance conservation efforts. Agriculture contributes substantially to greenhouse gas emissions through sources such as livestock, synthetic fertilizers, and fossil fuel consumption. These emissions contribute to climate change and global warming. Additionally, modern farming practices often lead to deforestation, habitat loss, and soil degradation, exacerbating biodiversity loss and reducing soil health. Water usage in agriculture also poses significant challenges, with high water consumption and pollution from runoff affecting water resources and aquatic ecosystems. To address these issues, several strategies can be employed to reduce the carbon footprint of agriculture. Adoption of sustainable farming practices such as conservation tillage and no-till farming can enhance soil carbon sequestration, improving soil health and reducing emissions. Agroforestry and cover cropping further contribute by capturing atmospheric carbon and improving soil structure. The integration of renewable energy sources like solar and wind power in farming operations, along with energy-efficient technologies, can also reduce reliance on fossil fuels and lower overall greenhouse gas emissions. Promoting conservation involves implementing practices that protect and restore natural resources. Soil conservation methods, including erosion control techniques like terracing and contour plowing, help maintain soil health and prevent degradation. Efficient water management strategies, such as drip irrigation and rainwater harvesting, reduce water consumption and mitigate pollution from runoff. Biodiversity conservation can be supported through the preservation of natural habitats and the promotion of biodiverse farming systems, which enhance ecosystem resilience and stability. Effective policy frameworks and support mechanisms are crucial for driving the adoption of these strategies. Government policies, including environmental regulations and incentives, play a pivotal role in encouraging sustainable practices. Research and innovation are essential for developing new technologies and practices, while education and extension services ensure the dissemination of knowledge and best practices to farmers. Modern agricultural practices have significant environmental impacts, but through the adoption of sustainable practices and innovative strategies, it is possible to reduce carbon footprints and promote conservation. Continued research, supportive policies, and effective implementation of conservation strategies are essential for achieving a more sustainable agricultural future. Keywords: Environmental Impact, Agricultural Practices, Carbon Footprint.

Vegetation restoration enhancing soil carbon sequestration in karst rocky desertification ecosystems: A meta-analysis

Vegetation restoration measures have been increasingly employed to alleviate rocky desertification in karst ecosystems. However, the comprehensive effects of these interventions on soil properties and soil organic carbon (SOC) remain poorly understood. Herein, we gathered 644 paired observations from 68 studies and conducted a meta-analysis to quantify the performance of different vegetation restoration measures including moss (MS), grassland (GL), cash crop (CP), shrub (SH), and secondary forest (SF) through soil properties and SOC. Our results demonstrated significant effects of MS, GL, CP, SH, and SF on soil biotic and abiotic factors, each with distinct response characteristics. Particularly, MS significantly enhanced all soil properties (excluding a slight decrease in soil pH by 10.8%). Moreover, MS, GL, CP, SH, and SF could elevate SOC by 32.1%, 17.6%, 24.9%, 59.2%, and 48.7% respectively. Utilizing random forest and linear regression models, we identified primary drivers for SOC in MS, GL, CP, SH, and SF as soil moisture content, arbuscular mycorrhizal fungi, soil microbial phosphorus, total nitrogen, and β-1,4-glucosidase, respectively. This meta-analysis underlined the varied effects of vegetation restoration measures on soil properties and advocates for restoration measures that prioritize plant productivity and reduce soil temperature during the karst rocky desertification restoration process. Additionally, this study underscores the pivotal role of vegetation rehabilitation in environmental conservation and carbon sequestration of ecologically vulnerable regions.

The Role of Organic Farming for Climate Change Mitigation and Sustainable Development: A Review

Climate Change, exacerbated by human activities such as fossil fuel combustion and greenhouse gas emissions like carbon dioxide (CO2), is a pressing global crisis that disrupts long-term weather patterns, ecosystems, and human well-being. Organic agriculture offers a viable solution to mitigate these effects. By lowering greenhouse gas emissions and enhancing soil carbon sequestration, organic farming strengthens ecosystem resilience. Practices such as eliminating synthetic fertilizers and pesticides, rotating crops, and utilizing organic waste foster robust agricultural systems capable of enduring extreme weather and water scarcity. This paper provides an in-depth analysis of how organic farming contributes to climate change mitigation, detailing practices that support soil carbon sequestration, reduce nitrogen oxide (N2O) emissions, and boost biodiversity. It also addresses challenges such as emissions measurement and consumer behaviour, emphasizing the need for further research and supportive policies. Organic agriculture not only advances sustainable development but also promotes food security and environmental sustainability in the face of climate change.

The Impact of Ecological Land Consolidation Projects on Soil Carbon Sequestration Capacity

Land consolidation is an important measure to expand the scale of arable land, improve the working environment of farmland, enhance agricultural productivity, and improve the production and living conditions of farmers. However, for a long time, land consolidation has remained at the stage of improving agricultural infrastructure. With the proposal of ecological and environmental protection concepts, ecological land consolidation projects are about to emerge. In the process of promoting this project, soil carbon sequestration capacity is one of the most important measures of ecological and environmental protection. Overview of the definition and connotation of soil organic carbon, and analysis of the impact of ecological land remediation projects on soil carbon sequestration capacity. On this basis, an overview of soil carbon sequestration measures in ecological land consolidation projects is provided, providing theoretical support and technical guidance for strengthening carbon sequestration work and enhancing soil carbon sequestration capacity in ecological land consolidation projects.

Easily overlooked petiole traits are key factors that affect soil carbon sequestration in plantations in karst areas

Vegetation restoration in karst areas has shifted from expanding planting areas to the collective enhancement of various ecological functions, especially carbon sequestration. Identifying and regulating key plant functional traits involved in the carbon cycle is an effective approach to increase carbon sequestration. However, reports on the significant contribution of petiole traits to the carbon cycle are scarce. Eucalyptus globulus and Bauhinia purpurea plantations in Liujiang river basin were investigated in this study. Petiole traits, understory characteristics, and soil organic carbon have been measured. The aim is to explore key effect of petiole traits for increasing soil carbon sequestration and to provide scientific evidence for the high-quality development of plantations in karst areas. The results indicate that in Eucalyptus globulus plantations, when the understory vegetation coverage is below 50 %, petioles tend to elongate rather than thicken, leading to an increase in specific petiole length. In Bauhinia purpurea plantations, petioles consistently tend to increase diameter. However, when specific leaf area decreases, specific petiole length increases. In both plantations, an increase in specific petiole length accelerates leaf shedding. It leads to increased litter accumulation so that soil carbon content increases. In Eucalyptus globulus plantations, to enhance soil carbon sequestration as an ecological goal, it is recommended to keep the soil total nitrogen below 1.20 mg/g, to control understory vegetation coverage below 50 %, and to limit the extension of Bidens pilosa. In Bauhinia purpurea plantations, within 100 m of altitude, the soil total nitrogen can be controlled below 1.00 mg/g to increase soil organic carbon from large leaf shedding due to the increase of specific petiole length. At lower altitudes, increasing soil total nitrogen can enhance understory vegetation coverage, allowing soil organic carbon to originate from both leaf shedding and understory vegetation residues.

Spatiotemporal variations and driving factors of farmland soil organic carbon in various landforms of a complex topography

Estimating the spatiotemporal variations and driving factors of farmland soil organic carbon density (SOCD) is of great significance for enhancing soil carbon sequestration capacity. Herein, a large region of complex topography was targeted, which includes hill–mountain, valley–basin, and plain–platform. Based on the massive amounts of sampling data (57,254 measured values) and a large-scale soil map of 1:10,000 (371,976 polygonal patches), the gravity center migration model and gray correlation model were used to quantify the spatiotemporal variations and driving factors of farmland SOCD. The results indicated that the farmland soils in the study area had dual functions of carbon source and sink during 1982–2018, of which 45.50 % and 54.50 % were identified as carbon source and sink, respectively. Specifically, the SOCD for the entire study area, its hill–mountain, and valley–basin increased from 2.79 kg m−2, 2.97 kg m−2, and 3.06 kg m−2 to 2.87 kg m−2, 3.06 kg m−2, and 3.14 kg m−2, respectively, with 0.08 kg m−2 carbon sequestrations and a northeast migration direction for the SOCD gravity center (angle: 21.94°, 23.56°, and 18.82°; distance: 1.56 km, 2.73 km, and 3.20 km). There was a smaller increase of 0.07 kg m−2 in SOCD for the plain–platform from 2.38 kg m−2 (1982) to 2.45 kg m−2 (2018), and the SOCD gravity center migrated to the southwest with an angle of −172.46° and a distance of 1.84 km. Thus, the spatiotemporal variations of farmland SOCD in various landforms varied greatly. Over the past 36 years, SOCD variations were driven by a combination of intrinsic soil factors and external factors such as human disturbance. However, the driving effects of these factors on the landforms of hill–mountain, valley–basin, and plain–platform were quite different in size and order. Therefore, we suggest that topography must be considered when formulating policies to improve soil carbon sequestration, and priority should be given to landform-specific SOCD variation and the factors contributing to them.

Enhancing lucerne (Medicago sativa) yield and nutritional quality: a meta-analysis of fertilization types and environmental factors in China.

Lucerne (Medicago sativa), is a cornerstone of China's livestock industry, however, due to the backward agronomic strategies and technology, lucerne in China faces cultivation challenges that result in lower productivity and quality than global standards. Therefore, we undertook a meta-analysis to evaluate the impact of five distinct fertilization types on lucerne yield and nutritional quality in various locations in China. The fertilizer practices included manure application, combined mineral fertilizer and manure application (FM), biological fertilizer application, unbalanced application of two or more mineral fertilizer types, and balanced mineral fertilizer application. Furthermore, we investigate influential factors of yield and quality of lucerne under fertilization, including climatic variables (mean annual precipitation, mean annual temperature), initial soil properties (soil organic carbon; total nitrogen, pH), and agronomic factors (seeding rate, harvest frequency, and lucerne stand age). Our study analyzed 53 published papers to discern the most beneficial fertilizer for enhancing lucerne yield and nutritional quality. The results showed that the fertilizer practices, on average, significantly improved yield by 31.72% and crude protein content by 11.29%, with FM emerging as the most effective, this is because mineral fertilizers provide available nutrients for lucerne, manure provides essential organic matter for microorganisms and improve soil properties. In addition, the fertilizer practices significantly reduced neutral and acid detergent fiber contents by 6.28% and 8.50%, respectively, while increasing ash content and relative feeding value. Furthermore, climatic variables, soil properties, and planting system factors such as sowing date and harvest frequency significantly affected yield and nutritional quality. The practical implications of our results emphasize the need for balanced and strategic fertilizer application to optimize lucerne production and highlight the potential to adjust cultivation practices according to environmental conditions. Balanced and strategic fertilizer application can simultaneously improve soil properties, enhance soil carbon sequestration, and reduce the emission of greenhouse gases from the soil, which is a vital measure for realizing sustainable agricultural development.

Soil carbon offset markets are not a just climate solution

There is growing interest in enhancing soil carbon sequestration (SCS) as a climate mitigation strategy, including neutralizing atmospheric emissions from fossil‐fuel combustion through the development of soil carbon offset markets. Several studies have focused on refining estimates of the magnitude of potential SCS or on developing methods for soil carbon quantification in markets. We call on scientists and policy makers to resist assimilating soils into carbon offset markets due to not only fundamental flaws in the logic of these markets to reach climate neutrality but also environmental justice concerns. Here, we first highlight how carbon offset markets rely on an inappropriate substitution of inert fossil carbon with dynamic stocks of soil carbon. We then note the failure of these markets to account for intersecting anthropogenic perturbations to the carbon cycle, including the soil carbon debt and ongoing agricultural emissions. Next, we invite scientists to consider soil functions beyond productivity and profitability. Finally, we describe and support historical opposition to offset markets by environmental justice advocates. We encourage scientists to consider how their research and communications can promote diverse soil functions and just climate‐change mitigation.

Applying conditioners to address the issues of carbon loss and cadmium pollution in the karst paddy-oil crop system

The fragile ecosystem and unique parent material in the karst region lead to severe carbon loss and cadmium pollution. Additionally, the rice-oilseed rotation system exacerbates the accumulation of cadmium in crops. Therefore, it is necessary to find a sustainable land use approach that ensures crop quality while promoting soil carbon sequestration. This article provides an overview of cutting-edge technologies to enhance soil carbon sequestration capacity, and it discovers that the application of amendments has a significant effect on reducing cadmium content in crops and improving soil organic carbon levels. Through experimental analysis, The results indicate that the conditioner in group T4 (Humic acids) can effectively passivate cadmium elements in the soil, reducing the cadmium content in rice and rapeseed tissues. Overall, our research indicates that humic acid amendments not only enhance soil carbon sequestration capacity but also significantly reduce cadmium content in crops and increase crop yields. These findings highlight the significant value of humic acid amendments in the rice-oilseed rotation system in the karst region, providing scientific evidence and theoretical support for promoting sustainable development in the area.

Hyperspectral sensing and mapping of soil carbon content for amending within-field heterogeneity of soil fertility and enhancing soil carbon sequestration

Hyperspectral sensing and mapping of soil carbon content for amending within-field heterogeneity of soil fertility and enhancing soil carbon sequestration

Enhancing soil health and carbon sequestration through phytogenic treatment: insights into microbial functional pathways in pasture dieback affected soil

Abstract Background and aims Phytogenic bioactive plant products have shown promise in mitigating Australian pasture dieback (PDB) syndrome, a complex condition that adversely affects pasture productivity and sustainability. PDB is characterised by the progressive decline of grass, resulting in reduced soil organic matter. Recent studies have indicated that soil microbial communities play a crucial role in the remediation of affected pastures. In our previous research, the application of a phytogenic secondary metabolic product demonstrated a positive impact on soil microbial diversity, and it significantly increased pasture biomass. Building upon our previous study, we aimed to further investigate the mechanisms underlying pasture improvement through phytogenic treatment by spraying. Methods Here, we conducted a shotgun metagenomic investigation of the soil microbiome functional pathways affected by the phytogenic treatment. Results The application of phytogenic treatment to the PDB-affected soil resulted in a notable increase in soil microbial functional richness and diversity and showed alterations in beta diversity. Among the 65 significantly altered functional pathways, 54 showed an increase, while 11 decreased in response to the phytogenic treatment. The treatment altered the soil’s functional capacity towards increased production of biomolecules, including amino acids, lipids, and cofactors, thus enhancing the soil’s nutritional value. Furthermore, the phytogenic treatment significantly increased pathways involved in soil detoxification and carbon sequestration, suggesting its potential to promote soil health and carbon storage. Conclusion Our findings contribute to a better understanding of the mechanisms involved in improving the soils affected by pasture dieback. These insights will help develop sustainable strategies for pasture production.

Soil acidification enhanced soil carbon sequestration through increased mineral protection

Soil acidification enhanced soil carbon sequestration through increased mineral protection

Ammoniated straw returning: A win-win strategy for increasing crop production and soil carbon sequestration

Increasing crop production and soil carbon sequestration is critical for sustainable agricultural development. Straw returning, a common agricultural practice, positively affects grain yield and soil organic carbon. Nevertheless, the slow decomposition rate and high carbon-to-nitrogen ratio of straw are significant obstacles to its effectiveness. Ammonifying straw using urea and calcium hydroxide may be a promising solution, whereas limited information is available on the impacts of ammoniated straw returning on crop production and soil carbon sequestration. Therefore, in a winter wheat-summer maize rotation system, we conducted an experiment with three straw returning treatments (T1, straw removal; T2, traditional straw returning; T3, ammoniated straw returning) to investigate their impacts on crop growth, grain yield and yield components, carbon inputs and outputs, and net ecosystem carbon budget (NECB). The results showed that T3 outperformed T2 regarding increasing leaf area index and aboveground biomass. Ear density and thousand kernel weight of winter wheat and hundred kernel weight of summer maize were ranked T1 < T2 < T3, with no significant differences between treatments for other grain yield components. Consequently, winter wheat, summer maize, and annual grain yields were the highest under T3, followed by T2 and T1. In comparison with T1, T2 and T3 increased annual total carbon inputs by 5463 and 7271 kg C ha–1, respectively, due to the increased carbon inputs from returned straw and net primary productivity. Annual carbon total outputs, primarily from aboveground biomass removal at harvest and carbon respiration, increased by 3305 kg C ha–1 under T2 and 4264 kg C ha–1 under T3, compared with T1. Balancing annual total carbon inputs and outputs, T1, T2, and T3 had annual NECB values of –1215, 944, and 1793 kg C ha–1, respectively. Therefore, the T1 agroecosystem acted as a carbon source, whereas the T2 and T3 agroecosystems, particularly T3, acted as a carbon sink on an annual scale. These results suggest that ammoniated straw returning may be a superior straw application practice for increasing crop production and soil carbon sequestration simultaneously.

Straw incorporation and nitrogen fertilization enhance soil carbon sequestration by altering soil aggregate and microbial community composition in saline-alkali soil

Straw incorporation and nitrogen fertilization enhance soil carbon sequestration by altering soil aggregate and microbial community composition in saline-alkali soil

Response of soil CO2 emissions and water-carbon use efficiency of winter wheat to different straw returning methods and irrigation scenarios.

The shortage of water resources and the increase of greenhouse gas emissions from soil seriously restrict the sustainable development of agriculture. Under the premise of ensuring a stable yield of winter wheat through a reasonable irrigation scenario, identifying a suitable straw returning method will have a positive effect on agricultural carbon sequestration and emission reduction in North China Plain. Straw burying (SR) and straw mulching (SM) were adopted based on traditional tillage under in the winter wheat growing season of 2020-2021 and 2021-2022. Three irrigation scenarios were used for each straw returning method: no irrigation (I0), irrigation 60 mm at jointing stage (I1), and irrigation of 60 mm each at the jointing and heading stages (I2). Soil moisture, soil respiration rate, cumulative soil CO2 emissions, yield, water use efficiency (WUE) and soil CO2 emission efficiency (CEE) were mainly studied. The results showed that, compared to SM, SR improved the utilization of soil water and enhanced soil carbon sequestration. SR reduced soil respiration rate and cumulative soil CO2 emissions in two winter wheat growing seasons, and increased yield by increasing spike numbers. In addition, with an increase in the amount of irrigation, soil CO2 emissions and yield increased. Under SR-I1 treatment, WUE and CEE were the highest. SR-I1 increases crop yields at the same time as reducing soil CO2 emissions. The combination of SR and irrigation 60 mm at jointing stage is a suitable straw returning irrigation scenario, which can improve water use and reduce soil CO2 emission in NCP. © 2023 Society of Chemical Industry.

Crop yield increments will enhance soil carbon sequestration in coastal arable lands by 2100

Coastal lands are crucial arable land reserves that play a vital role in ensuring future global food security. In arable coastal lands, low soil quality often results in limited crop yield and soil organic carbon (SOC), making them promising sites for enhancing both soil carbon sequestration and agricultural production. However, a scarcity of long-term site experiments has led to a research gap regarding SOC sequestration in coastal arable lands, leaving potential uncertainties due to variations in planting systems, crop yields, and the influence of climate change. In this study, we focused on the Yellow River Delta (YRD) in China, which is a typical coastal agricultural area. We verified the adaptability of the Denitrifcation-Decomposition (DNDC) model in coastal farmlands based on an 11-year long-term observation experiment and continuous sampling survey data. We further explored the spatiotemporal changes of regional SOC stocks under two Shared Socio-Economic Pathways (SSPs) scenarios based on five Global Climate Models (GCMs) derived from the Coupled Model Intercomparison Project Phase 6 (CMIP6), along with three yield increase scenarios from 2020 to 2100. The results indicated that promoting single-cotton cultivation in coastal saline–alkali lands would result in at least 88.2% of farmland being converted into carbon sinks. In contrast, promoting the cultivation of a wheat–maize rotation system can promote regional SOC sequestration as a whole, with a maximum increase of 31.90 Mg C ha−1. By 2100, the SOC stocks decreased in cotton and wheat–maize rotation farmland by 3.9% and 11.6%, respectively, in the SSP585 scenario compared with that in the SSP126 scenario. Except for farmlands with wheat-maize rotation cropping system under the SSP126 scenario, the SOC stocks in all other scenarios are projected to reach their theoretical maximum values before 2050. Additionally, when reaching the North China Plain (S1) and national (S2) high-yield levels of farmland, the SOC stocks in cotton farmland by 2100 increased by 16.7% and 21.6%, respectively, whereas the SOC stocks in wheat-maize farmland increased by 1.8% and 4.8%, respectively. Our study revealed the mutually beneficial relationship between yield increment and SOC sequestration in coastal farmlands under climate change, as well as the potential for future SOC sequestration. We provided scientific support for land management and climate change mitigation strategic decision-making in coastal saline–alkali farmlands.

Impact of future climate warming on soil organic carbon stocks in Inner Mongolia, China

Accurate assessment on temporal and spatial changes in soil organic carbon stocks (SOCS) is essential for evaluating the potential of soil carbon sequestration and formulating effective strategies to mitigate climate change. While most SOCS studies have focused on topsoil, there remains a lack of comprehensive understanding regarding the vertical distribution of SOCS within soil profiles. Furthermore, the key environmental variables influencing deep SOCS are still not fully comprehended. In this study, we employed an integrated approach combining equal-area spline function, boosted regression trees model (BRT), and the space-for-time substitution method to accurately model the three-dimensional distribution of SOCS in response to climate warming in Inner Mongolia, China. A total of 12 environmental variables (generated from climate, topography, biological, and soil property factor) and 208 soil profile data were selected to construct the model. The 10-fold cross-validation technique was employed to assess the predictive performance of the BRT model for soil organic carbon stocks (SOCS) at various depths, using four accuracy validation indicators: root mean square error (RMSE), mean absolute error (MAE), coefficient of determination (R2), and Lin's concordance correlation coefficient (LCCC). The results demonstrated the BRT model accurately predicted SOCS with higher LCCC and R2 values, as well as lower RMSE and MAE values. The predicted map revealed higher SOCS concentration in the northeast and lower concentration in the western area. Grassland and forest land were found to store a majority of SOCS, with over 46 % located the topsoil depth of 30 cm. Furthermore, under different climate warming scenarios with temperature increase of 1.5 ℃, 2 ℃ and 4 ℃, there was a corresponding decreased in SOCS by 7 %, 9 % and 17 % respectively at a soil depth. Additionally, this study identified MAT and NDVI as primary environmental variables influencing the spatial distribution of three-dimensional scale SOCS. We believed that accurately predicting and mapping three-dimensional SOCS under different climate warming scenarios will contribute to the development of scientifically sound land management policies aimed at enhancing soil carbon sequestration in the region.

Cropping System Stability Drives SOC Sequestration and Increases Saturation Deficit in Hot Arid Durum Wheat Cropping Systems

Stability analysis has been extensively employed in evaluating the genotype x environment interaction, but it can also be conveniently applied to cropping systems. This study applied stability analysis to a long-term experiment (1998–2016) conducted in an experimental farm in southern Italy. The experiment involved two standard semi-arid cropping systems (WW—durum wheat monocropping and WP—durum wheat–field pea rotation), with two nitrogen fertilization levels (60 kg ha−1—N60 and 120 kg ha−1—N120), along with an unfertilized control (N0). Soil organic carbon (SOC) was estimated in all treatments at the end of the experiment to investigate the potential for SOC sequestration and soil C saturation by analyzing the stability of all investigated cropping conditions in relation to SOC sequestration. The study also investigated the relationship between C input and SOC sequestration. SOC sequestration per year was higher in WW than in WP, confirming that including legumes in the rotation did not enhance the SOC content. Similarly, the positive impact of nitrogen application on biomass yield did not affect SOC accumulation. The stability analysis revealed that over the long term, WW exhibited greater stability than WP, suggesting that, in semi-arid environments, a more stable cropping system can enhance soil carbon sequestration, with nitrogen fertilization exerting a scarce influence. Segmented regression analysis identified two distinct patterns of SOC accumulation based on C input, separated by a definite threshold of C input (breakpoint) quantified at 14.7 Mg ha−1. It was found that the steady-state C level, achieved after the accumulation of this C input, was reached much faster in WW than in WP, in which it could only be inferred at 23 years. In conclusion, this study underscores the role of cropping system stability in driving SOC sequestration. Furthermore, it emphasizes the potential of stability analysis in assisting stakeholders in refining their strategies for different cropping conditions in dry and rainy environments.

Long-Term Effect of Prescription-Based Fertilization on Culturable Soil Microorganisms and Carbon Dynamics in Northwest Himalayas

ABSTRACT The different approaches of fertilizer application can play an important role in altering soil biological properties, organic carbon retention, and its dynamics. The mechanisms implicit in the long-term accumulation and protection of soil organic carbon and improvement in soil biological environment, however, have not been well documented for maize crop cultivated in acid soils of the Northwest Himalayas. Based on a 13-year experiment, the effects of prescription-based fertilization on soil culturable microorganisms and soil carbon dynamics were investigated under a continuous maize cropping at Palampur, India. The experiment was initiated during 2007 in randomized block design (RBD) with 8 treatments which were replicated three times. The soil of the experimental site was acidic, having silty clay loam texture and classified taxonomically as “Typic Hapludalf.” The surface soil samples from 0.15 m depth were drawn after the harvest of maize crop in 2019 for estimation of culturable soil microorganisms and carbon dynamics. Based on soil-test crop response approach, the application of 110 kg ha−1 nitrogen and 82 kg ha−1 phosphorus with 5 Mg ha−1 farmyard manure (FYM) for attaining the target yield of 4.0 Mg ha−1 of maize recorded significantly highest population of soil bacteria (40.7 × 105 CFU g−1 soil), fungi (57.0 × 105 CFU g−1 soil), actinomycetes (38.2 × 105 CFU g−1 soil), microbial biomass carbon (147.2 µg g−1), dehydrogenase enzyme activity (4.3 µg TPF g−1 hr−1), different fraction of organic carbon, i.e. very labile (4.6 g kg−1), labile (2.60 g kg−1), less labile (2.70 g kg−1), non-labile (2.94 g kg−1), soil organic carbon (8.9 g kg−1), total soil organic carbon (11.8 g kg−1), total carbon stock (16.1 t ha−1), carbon sequestration (3.24 t ha−1) and carbon sequestration rate (1.24t ha−1year−1) when compared with control plot. Based on the data associated with microbial soil environment and carbon dynamics, it was inferred that application of prescription-based fertilizers along with farmyard manure for a longer period not only improved population of soil culturable microorganisms but also enhanced soil carbon sequestration and minimized carbon di-oxide (CO2) emission to atmosphere.

Variations in Microbial Residue and Its Contribution to SOC between Organic and Mineral Soil Layers along an Altitude Gradient in the Wuyi Mountains

Microbes are crucial components of soil, and their residue carbon plays a significant role in the formation and stabilization of soil carbon pools. However, current research on microbial residue carbon has predominantly focused on surface soils, with limited studies on deep soils. The patterns of variation along soil profiles and their controlling factors remain unclear. Therefore, this study aimed to investigate the soils from different elevations in the Wuyi Mountains, specifically focusing on the organic layers (0–10 cm) and mineral layers (30–40 cm). Amino sugars were utilized as biomarkers for the microbial residue, and the RDA (redundancy analysis) method was employed to analyze the patterns of microbial residue carbon in different soil layers and to identify the factors that control them. The results indicate that there are significant differences in the microbial residue carbon content and its contribution to soil organic carbon (SOC) between the different soil layers. Specifically, between the organic layer and the mineral layer, the microbial residue carbon content exhibited an increasing trend, whereas its contribution to SOC decreased. This finding suggests that soil layer type has a notable impact on microbial residue carbon content and its contribution to SOC. Moreover, fungal residue carbon content was found to be higher than bacterial residue carbon content in both soil layers. However, the ratio of fungal residue carbon to bacterial residue carbon gradually decreased between the organic layer and the mineral layer. This implies that although fungal residue carbon remains dominant, the contribution of bacterial residue carbon to the soil carbon pool increases as the soil transitions to the mineral layer. The total soil carbon content, elevation, and C/N ratio exhibited positive correlations with fungal and bacterial residue carbon, indicating their significant roles in the accumulation of microbial residue carbon in soils. Notably, elevation emerged as a key regulating factor in the accumulation of microbial residue carbon, explaining 85.8% and 67.9% of the variations observed in the organic layer and the mineral layer respectively. These research findings contribute to a better understanding of the soil carbon cycling process and its mechanisms, providing a scientific basis for developing strategies to enhance soil carbon sequestration by manipulating micro-organisms.