Agricultural Carbon Sequestration Research Articles

Transformation and Sequestration of Total Organic Carbon in Black Soil under Different Fertilization Regimes with Straw Carbon Inputs

In the context of the carbon peak and carbon-neutral era, it is crucial to effectively utilize maize straw as a resource for achieving carbon (C) sequestration and emission reduction in rural agriculture. Maize straw carbon undergoes two processes after being added to the soil: mineralization (decomposition) and humification (synthesis) by soil animals and microorganisms. These processes contribute to the reintegration of carbon into the agroecosystem’s carbon cycle. However, understanding of the transformation and stabilization of straw carbon, as well as the differences in C fixation capacity in soils with various fertilization treatments in black soils, remains limited. This study aims to quantify the relationship between straw carbon input and organic carbon sequestration in various fertilization treatments of black soil. Based on a long-term positional fertilization trial (45 years) in black soil, 13C-labeled maize straw (1.5 g in 120 g of dry soil) was applied and combined with an in situ incubation method using carborundum tubes. Throughout the 360-day trial, we observed the influence of fertilization on soil total organic C levels, organic carbon δ13C values, maize straw addition rate, and straw C fixation capacity. The decomposition of straw was most prominent during the initial 60 days of the incubation period, followed by a gradual decrease in the rate of decomposition. Compared with day 0, the SOC δ13C value and straw C residue rate were highest in the no-fertilization treatment (CK) after 360 days of incubation. The amount of organic carbon transformed and fixed in the soil was significantly higher in the organic fertilizer treatment (M) compared to other treatments, highlighting the stronger decomposition, transformation, and carbon fixation capacity of straw carbon in the M treatment. Moreover, the highest carbon storage of 43.23 Mg·ha−1 was observed in the M fertilization treatment after 360 days, which was significantly different from other treatments (p < 0.05). The study demonstrates that soil with low fertility exhibits increased sequestration potential for straw carbon. Additionally, organic fertilizer input would increase soil organic carbon storage and facilitate straw carbon conversion.

Soil moisture and soil organic carbon coupled effects in apple orchards on the Loess Plateau, China

A large number of economic forests, especially apple orchards (AOs) in the Loess Plateau region of China, have been planted to develop the local economy and increase the income of farmers. The two main constraints preventing AOs on the Loess Plateau from developing sustainably and producing a high and steady yield are soil moisture content (SMC) and soil organic carbon (SOC). Nevertheless, little is currently known about the contributions of roots to these changes in the soil profile and the temporal modes of the SMC-SOC coupled effects. In our research, we analyzed the dynamic changes in SMC and SOC in AOs of various years in northern Shaanxi Province, as well as the coupled relationship between the two, and attempted to describe the function of roots in these changes. Research have shown: (1) As the age of the AOs increased, the SMC continued to decline throughout the 0–500 cm profile, especially at depths of 100–500 cm. SMC depletion mainly occurred in AOs aged 20 years (30.02%/year) and 30 years (31.18%/year). (2) Compared with abandoned land (AL), all the AOs except for the 6-year-old AO showed a carbon sequestration effect, and the carbon sequestration effect increased with age. The carbon sequestration rate of the 12-year-old AO was the highest and then decreased with age. Both surface and deeper soils showed better carbon sequestration, with a large amount of SOC being sequestered in deeper soil layers (> 100 cm). (3) The coupled effects of SMC and SOC varied with age and depth. The SMC in the deeper layers was significantly negatively correlated with SOC. Root dry weight density (RDWD) was significantly negatively correlated with SMC and significantly positively correlated with SOC. Path analysis suggested that SMC directly affects SOC at different soil depths, and regulates SOC by affecting RDWD, but these effects are significantly different at different depths. Therefore, we propose that management of AO should focus on the moisture deficit and carbon sequestration capabilities of deeper soils to ensure the sustainability of water use in AOs and the stability of agricultural carbon sequestration on the Loess Plateau.

Soil bacterial community characteristics and its effect on organic carbon under different fertilization treatments.

By implementing small-scale and efficient fertilization techniques, it is possible to enhance the activity of microorganisms, thereby improving soil carbon sequestration and ecological value in agriculture. In this study, field experiments were conducted using various types of fertilizers: organic fertilizer, microbial fungal fertilizer, composite fertilizer, and an unfertilized control (CK). Additionally, different dosages of compound fertilizers were applied, including 0.5 times compound fertilizers, constant compound fertilizers, 1.5 times compound fertilizers and CK. Using advanced technologies such as Illumina MiSeq high-throughput sequencing, PICRUSt2 prediction, Anosim analysis, redundancy analysis, canonical correlation analysis, and correlation matrix, soil organic carbon (SOC) content and components, bacterial diversity, metabolic functions, and interaction mechanisms were examined in different fields. The results showed pronounced effects of various fertilization modes on SOC and the bacterial community, particularly in the topsoil layer (0-20 cm). Organic fertilizer treatments increased the richness and diversity of bacterial communities in the soil. However, conventional doses and excessive application of compound fertilizers reduced the diversity of soil bacterial communities and SOC content. Additionally, different fertilization treatments led to an increase in easily oxidizable organic carbon (EOC) contents. Interestingly, the relationship between SOC components and soil bacteria exhibited inconsistency. EOC was positively correlated with the bacterial diversity index. Additionally, Chloroflexi exhibited a negative correlation with both SOC and its components. The influence of metabolismon primary metabolic functions on the content of SOC components in the soil was more notable. It included seven types of tertiary functional metabolic pathways significantly correlated with SOC components (p < 0.05). These findings enhance the understanding of the relative abundance of bacterial communities, particularly those related to the carbon cycle, by adjusting agricultural fertilization patterns. This adjustment serves as a reference for enhancing carbon sinks and reducing emissions in agricultural soils.

The Effect of Long-Term Crop Rotations for the Soil Carbon Sequestration Rate Potential and Cereal Yield

Depending on the type of agricultural use and applied crop rotation, soil organic carbon accumulation may depend, which can lead to less CO2 fixation in the global carbon cycle. Less is known about organic carbon emissions in different crop production systems (cereals, grasses) using different agrotechnologies. There is a lack of more detailed studies on the influence of carbon content in the soil on plant productivity, as well as the links between the physical properties of the soil and the absorption, viability, and emission of greenhouse gases (GHG) from mineral fertilizers. The aim of this study is to estimate the long-term effect of soil organic carbon sequestration potential in different crop rotations. The greatest potential for organic carbon sequestration is Norfolk-type crop rotation, where crops that reduce soil fertility are replaced by crops that increase soil fertility every year. Soil carbon sequestration potential was significantly higher (46.72%) compared with continuous black fallow and significantly higher from 27.70 to 14.19% compared with field with row crops and cereal crop rotations, respectively, intensive crop rotation saturated with intermediate crops. In terms of carbon sequestration, it is most effective to keep perennial grasses for one year while the soil is still full of undecomposed cereal straw from the previous crop. Black fallow without manure fertilization, compared to crop rotation, reduces the amount of organic carbon in the soil up to two times, the carbon management index by 2–5 times, and poses the greatest risk to the potential of carbon sequestration in agriculture.

Multi-driving paths for the coupling coordinated development of agricultural carbon emission reduction and sequestration and food security: A configurational analysis based on dynamic fsQCA

Exploring the coupling coordinated development of carbon emission reduction and sequestration (CERS) and food security in agriculture is conducive to mitigating climate change and achieving sustainable development goals. However, there is little research on the coupling coordinated development of these two systems. Based on panel data of 31 Chinese provinces from 2001 to 2021, this study used the dynamic fuzzy set qualitative comparative analysis (fsQCA) method to analyze the levels and driving paths of coupling coordinated development between agricultural CERS and food security. The results revealed that (1) the coupling coordination degree increased from 0.443 in 2001 to 0.489 in 2021, showing an upward trend. (2) We identified three driving paths of coupling coordination development: technology-driven, finance-driven and urban-development-driven. (3) The grain sown area and unit yield are core variables, serving as fundamental pillars, and their combination with technology or financial expenditure enhances this coordinated development. Notably, the grain sown area and unit yield exhibit a complementary relationship, while agricultural technology and financial expenditure demonstrate a substitution relationship. (4) Temporal analysis showed a consistent trend in the technology-driven and finance-driven paths. Regional analysis revealed marked heterogeneity: the technology-finance synergy path predominates in the remote west, the technology-driven path lies in the mountainous southwest, the finance-driven path clusters in the north, and the urban-development-driven path is located in economically advanced regions. Policymakers should formulate policies according to these different driving paths to promote coupling coordinated development.

Accelerated integrated watershed management enhances agricultural carbon sequestration and water use efficiency in an endorheic basin

With the continuous promotion of integrated river basin management (IRBM) in endorheic watersheds, the oasis surface processes have undergone significant changes. However, these underlying surface characteristics have not been well integrated into models for simulating carbon-water flux thus far. In this work, a regional SWAT-TECO model was constructed by coupling the modified TECO simulator with irrigation, film mulching, and soil hydraulic redistribution processes within the SWAT framework. The results indicated that the carbon sequestration and water use efficiency (WUE) showed an increasing trend after IRBM implementation in Heihe endorheic basin. WUE was projected to improve under future climate change and can be further enhanced by a maximum of 6.37 % through improving irrigation water use efficiency by 20 %, maintaining existing planting scale, increasing film mulching by 20 %, and reducing fertilizer application by 10 %. These findings can guide the formulation of high-water efficiency agricultural management strategies in global endorheic basins.

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.

Development and application of a new water-carbon-economy coupling model (WCECM) for optimal allocation of agricultural water and land resources

The optimal allocation of agricultural water and land resources is of great significance in ensuring sustainable food production and economic benefits of farmers. However, agriculture, as an important carbon cycle ecosystem, has paid limited attention to carbon sequestration in the optimal allocation of water and land resources. Therefore, this study developed a new water-carbon-economy coupling model (WCECM) for optimal allocation of agricultural water and land resources. In this model, the minimum water scarcity, maximum carbon sequestration and maximum economic benefits are taken as the optimization objectives. In addition, surface water volume and groundwater volume and planting area etc. were defined as constraints, respectively. Then, the model was solved using the Non-dominated Sorting Genetic Algorithm III (NSGA-III) and the Entropy-weighted-TOPSIS evaluation method. The developed model was demonstrated in the largest Farm, Youyi Farm, which is one of commercial grain production base in China to analyze the optimization of water and land resources from 2010 to 2019. We found that the new WCECM, based on the simulation of a complex coupled water-carbon-economy system, can realize the optimal allocation of agricultural water and land resources to protect regional water resources, increase carbon sequestration and adjust the agricultural planting structure. In detail, through the multi-objective optimization model, the planting structure and the allocation ratio of surface water and groundwater irrigation water consumption are more suitable for this study area. After the optimization, the area planted with Rice was significantly reduced, the area planted with Maize was increased, and the area planted with Soybean did not change significantly compared with the first two crops. The planting structure has changed from focusing on paddy cultivation to dryland cultivation, with the ratio of Rice area, Maize area and Soybean area being 3:6:1. The water consumption is constrained within manageable limits, with an average annual irrigation water consumption of 2.01 × 108 m3. The amount of carbon sequestered has increased significantly, with an average annual increase of 7.8 × 108 kg. Meanwhile, the optimized economic benefits increased slightly, with a value of ¥2.35 billion. In short, optimization of water and land resources is beneficial for improving farmers' incomes, increasing carbon sequestration in agriculture, and conserving water resources.

Patterns and drivers of carbon stock change in ecological restoration regions: A case study of upper Yangtze River Basin, China

Balancing ecology and human development has been a long and wide concern. The upper Yangtze River Basin (UYRB) of China has implemented large important ecological restoration projects since the last century. These restoration practices have changed land use patterns within the UYRB, consequently impacting the local carbon cycle. The most noteworthy project is the Grain for Green Program, which returns cropland to natural vegetation (forest and grassland). Yet the effects of restoration on land use change, carbon sequestration, and associated food production remain unclear. This study utilized remote sensing data and conversion coefficients to analyze the ecological-policy-induced land use changes of the UYRB from 2000 to 2020 and their impacts on terrestrial carbon sequestration. Linear regression, machine learning, and structural equation modeling (SEM) were utilized to evaluate the correlations between environmental and socio-economic factors and the distribution of carbon stocks. The results indicated positive effects of ecological activities on the UYRB, despite decreases in cropland. Over the past 20 years, the UYRB had sequestered carbon by a total amount of 1796 ± 926 Mt C. The spatial distribution of sequestered carbon demonstrated a strong correlation with slopes, followed by temperatures. The SEM results indicated that agricultural production and carbon sequestration were enhanced synergically under land use changes. This further demonstrated the effectiveness of these land policies in achieving a balance between crop productivity and ecology protection. We emphasized the importance of vegetation restoration in achieving carbon neutrality and the necessity to continue these projects. We suggested a more reasonable land management for the future UYRB based on the characteristics of each geographical subregion. This work serves as an example of effective land management to other locations worldwide perusing the harmony of ecological restoration and human development.

Waterlogging increases greenhouse gas release and decreases yield in winter rapeseed (Brassica napus L.) seedlings

A sustainable future depends on increasing agricultural carbon (C) and nitrogen (N) sequestration. Winter rapeseeds are facing severe yield loss after waterlogging due to the effects of extreme rainfall, especially in the seedling stage, where rainfall is most sensitive. Uncertainty exists over the farming greenhouse gas (GHG) release of rapeseed seedlings following the onset of waterlogging. The effect of waterlogging on GHG release and leaf gas exchange in winter rapeseed was examined in a pot experiment. The experiment included waterlogging treatments lasting 7-day and 21-day and normal irrigation as a control treatment. According to our findings, (1) The ecosystem of rapeseed seedlings released methane (CH4) and nitrous oxide (N2O) in a clear up change that was impacted by ongoing waterlogging. Among them, N2O release had a transient rise during the early stages under the effect of seedling fertilizer. (2) The net photosynthetic rate, transpiration rate, stomatal conductance, plant height, soil moisture, and soil oxidation–reduction potential of rapeseed all significantly decreased due to the ongoing waterlogging. However, rapeseed leaves showed a significant increase in intercellular carbon dioxide (CO2) concentration and leaf chlorophyll content values after waterlogging. Additionally, the findings demonstrated an extremely significant increase in the sustained-flux global warming potential of the sum CO2-eq of CH4 and N2O throughout the entire waterlogging stress period. Therefore, continuous waterlogging can increase C and N release from rapeseed seedlings ecosystem and decrease yield. Therefore, we suggest increasing drainage techniques to decrease the release of agricultural GHGs and promote sustainable crop production.

Can rural e-commerce contribute to carbon reduction? A quasi-natural experiment based on China's e-commerce demonstration counties.

As information and communication technologies gain prominence in rural areas, rural e-commerce has emerged as a crucial mechanism for fostering agricultural and rural development. While the economic impact of rural e-commerce is widely studied, its effects on carbon emissions remain underexplored. Utilizing a multi-period DID model and Chinese county-level panel data from 2011 to 2017, this paper examines the impact of rural e-commerce on carbon emission reduction, employing the "comprehensive demonstration of e-commerce into villages" policy introduced by the Chinese government in 2014 as a quasi-natural experiment. Our findings show that e-commerce demonstration counties experienced a 10.6% reduction in carbon emissions compared to the control group, indicating a significant emission reduction effect. Further analysis reveals that rural e-commerce drives carbon reduction through decreased fertilizer usage, altered cropping structures, and enhanced transportation efficiency. Notably, rural e-commerce's emission reduction effect is more pronounced in major grain-producing regions and areas with higher digitalization levels. This study has crucial theoretical and practical implications for achieving carbon emission reduction and sequestration in agriculture and advancing green agricultural development.

Global distribution, trends and types of active fire occurrences

Fire occurrence is synonymous to terrestrial ecosystems and an important component of the Earth system. Climate change, vegetation characteristics, and human activity regulate fire occurrence and spread, however, fires also interact with them in multiple ways. Due to the complicated mechanisms of interactions between fire and land use or cover, the spatial distribution, change trends and land use or cover types of fire occurrences exist wide discrepancies in different regions or countries around the world. Therefore, the quantitative and spatial relationship and differences between fire and land use or cover at the global scale remain poorly understood systematically. Here, we combine active fire and land cover products during 2001–2020 to explore the spatio-temporal features, trends, and types of active fires from global to continental scales. Globally, the annual changes of monthly active fire occurrences kept a dramatic increase in first two or three years but a circuitous decrease since then. Most areas prevailingly experienced active fires for once to five times, a small part of areas clustered in Africa, Southeast Asia, and South America experienced active fires for over five times in the last 20-years. In particular, above 60 % of active fires (re-)occurred in forest and 20–25 % in cropland, whereas grassland and construction land only accounted for about 5 % and less than 2 % respectively. Driven by active fires, the conversion of forest to cropland accounted for nearly 60 % and the transition of cropland to forest (about 10 %) followed and formed an interactive circle. Our findings improve the understanding of fire-land cover change interactions, particularly agricultural expansion and forest loss driven by active fires. Future efforts on agricultural expansion, urban safety, carbon sequestration and biodiversity conservation should take the results of this research into account.

A study on GHG emission assessment in agricultural areas in Sri Lanka: the case of Mahaweli H agricultural region.

Agricultural activities contribute 7% to Sri Lanka's economy and account for 20% of the national greenhouse gas (GHG) emissions. The country aims to achieve zero net emissions by 2060. This study was aimed at assessing the present state of agricultural emissions and identifying mitigation strategies. The assessment involved estimating agricultural net GHG emissions from non-mechanical sources in the Mahaweli H region, Sri Lanka, in 2018 using the Intergovernmental Panel on Climate Change (IPCC 2019) guidelines. New indicators were developed to measure emissions for major crops and livestock and used to show the flow of carbon and nitrogen. The region's agricultural emissions were estimated to be 162,318 t CO2eq y-1, of which 48% was from rice field methane (CH4) emissions, 32% from soil nitrogen oxide emissions, and 11% from livestock enteric CH4 emissions. Biomass carbon accumulation offset 16% of the total emissions. Rice crops exhibited the highest emission intensity of 4.77 t CO2eq ha-1 y-1, while coconut crop had the highest abatement potential of 15.58 t CO2eq ha-1 y-1. Approximately 1.86% of the carbon input to the agricultural system was released as carbon-containing GHG (CO2 and CH4), whereas 1.18% of the nitrogen input was released as nitrous oxide. The findings of this study suggest extensive adaptations of agricultural carbon sequestration strategies and increased nitrogen use efficiency to achieve GHG mitigation targets. The emission intensity indicators derived from this study can be used for regional agricultural land use planning to maintain designated levels of emissions and implement low-emission farms.

Mapping Soil Organic Carbon in Floodplain Farmland: Implications of Effective Range of Environmental Variables

Accurately mapping soil organic carbon (SOC) is conducive to evaluating carbon storage and soil quality. However, the high spatial heterogeneity of SOC caused by river-related factors and agricultural management brings challenges to digital soil mapping in floodplain farmland. Moreover, current studies focus on the non-linear relationship between SOC and covariates, but ignore the effective range of environmental variables on SOC, which prevents the revelation of the SOC differentiation mechanism. Using the 375 samples collected from the Jiangchang Town near Han River, we aim to determine the main controlling factors of SOC, reveal the effective range of environmental variables, and obtain the spatial map of SOC by using the gradient boosting decision tree (GBDT) model and partial dependence plots. Linear regression was used as a reference. Results showed that GBDT outperformed linear regression. GBDT results show that the distance from the river was the most important SOC factor, confirming the importance of the Han River to the SOC pattern. The partial dependence plots indicate that all environmental variables have their effective ranges, and when their values are extremely high or low, they do not respond to changes in SOC. Specifically, the influential ranges of rivers, irrigation canals, and rural settlements on SOC were within 4000, 200, and 50 m, respectively. The peak SOC was obtained with high clay (≥31%), total nitrogen (≥1.18 g/kg), and total potassium contents (≥11.1 g/kg), but it remained steady when these covariates further increased. These results highlight the importance of revealing the effective range of environmental variables, which provides data support for understanding the spatial pattern of SOC in floodplain farmland, achieving carbon sequestration in farmland and precision agriculture. The GBDT with the partial dependence plot was effective in SOC fitting and mapping.

Digital Financial Inclusion, Land Transfer, and Agricultural Green Total Factor Productivity

Improving agricultural green total factor productivity is important for achieving high-quality economic development and the SDGs. Digital inclusive finance, which combines the advantages of digital technology and inclusive finance, represents a new scheme that can ease credit constraints and information ambiguity in agricultural production. First, this study focused on agro-ecological functions; we incorporated total agricultural carbon sequestration and emissions extraction into the evaluation system and used the mixed-direction-distance function to calculate agricultural green total factor productivity. Then, based on panel data from 31 provinces in China collected from 2011 to 2021, we used the two-way fixed effect model, the interactive fixed effect, and the plausibly exogenous variable method to test the impact of digital financial inclusion on agricultural green total factor productivity, and its mechanism of action. The panel-corrected standard error and fixed effect Driscoll–Kraay methods were used to account for the unobserved heterogeneity and cross-section dependence in the panel data. The results showed that digital financial inclusion can significantly improve agricultural green total factor productivity. This conclusion remained valid following robustness tests using the spatial econometric model and the method of changing explanatory variables. Digital financial inclusion can improve agricultural green total factor productivity by facilitating the transfer of agricultural land. Sound digital infrastructure and strict green credit policies enhance the role of digital inclusive finance in promoting the green development of agriculture. These conclusions could help the financial sector to formulate flexible, accurate, reasonable, and appropriate financial policies and products that would support agriculture, and enhance the role of digital inclusive finance in promoting sustainable agricultural development.

Evaluating the Spatiotemporal Characteristics of Agricultural Eco-Efficiency Alongside China's Carbon Neutrality Targets.

Agriculture has the dual effect of contributing to both carbon emissions and sequestration, and thus plays a critical role in mitigating global climate change and achieving carbon neutrality. Agricultural eco-efficiency (AEE) is an important measurement through which we can assess the efforts toward reduced emissions and increased sequestration. The purpose of this study was to understand the relationship between China's target of carbon neutrality and AEE through an evaluative model, so as to improve AEE and ultimately achieve sustainable agricultural development. The Super-SBM model scientifically measures the AEE based on provincial panel data collected between 2000 and 2020. We selected kernel density function and spatial distribution to explore the spatial and temporal evolutionary trends, and used a Tobit model to identify the drivers of AEE. The research shows that (1) China's agricultural system functions as a net carbon sink, with all provinces' agricultural carbon sequestration levels recorded as higher than their carbon emissions from 2000 to 2020. (2) Despite sequestration levels, the level of AEE in China is not high enough, and the average efficiency level from 2000 to 2020 is 0.7726, showing an overall trend where AEE decreased at first and then increased. (3) The AEE of each province is clearly polarized; there are obvious core-periphery characteristics and spatial distribution of clustered contiguous areas. Central provinces generally have lower efficiency, eastern and northeastern provinces have higher efficiency, and northeastern provinces always remain in the high-efficiency group. (4) Influencing factors show that urbanization, upgrading of industrial structure, financial support for agriculture, and mechanization have a significant positive impact on AEE. These findings have important implications for the promotion of the low-carbon green development of Chinese agriculture.

An Overview of Carbon Sequestration in Agricultural Soils of Latin America and the Caribbean

A major challenge in Latin America and the Caribbean (LAC) is to determine how to meet the ever-growing global needs for food while preserving natural ecosystems and contributing to climate change mitigation. In the region, continuing land use is occurring and has caused a significant soil organic carbon (SOC) loss. We estimated the SOC reduction in three representative ecosystems of the region: forests (4.21 petagrams of carbon, Pg C, over 30 years), grasslands (1.86−7.32 Pg C, over different periods) and mangroves (0.36 Pg C over 25 years). Increasing SOC stocks in agricultural lands can help to mitigate the SOC loss due to land use change, but multiple factors influence the dynamics and response of the agricultural production and carbon sequestration. Farmers are pivotal actors that contribute to food production and could maintain SOC stocks; however, incentives or fair compensation must be considered to enable this. Moreover, national, and continental policies are needed for land restoration and sustainable management of soil health as a living entity through adoption of nature-positive practices which enhance soil organic matter (SOM) stocks, increase use-efficiency of inputs, and lead to nutrition-sensitive agriculture.

The Interaction and Its Evolution of the Urban Agricultural Multifunctionality and Carbon Effects in Guangzhou, China

The dual identity of carbon sources and carbon sinks makes agriculture the focus of carbon neutralization-related research. Compared with traditional rural agriculture and urban industrial production, urban agriculture has its own particularities. It is of positive practical significance to explore the interaction and its evolution process between urban agricultural multifunctionality and carbon effects in seeking solutions to alleviate carbon pressure. Based on the changes in agricultural carbon emissions and carbon sequestration in Guangzhou from 2002 to 2020, we used the Granger causality analysis method to investigate the interaction between urban agricultural multifunctionality and carbon effects and then used the grey association model to analyse the evolution process of associative degrees between the two and divide the agricultural development stages. Finally, according to the practicalities of Guangzhou, we analyzed carbon effects generated in the multifunctional transformation of urban agriculture and put forward corresponding policy suggestions on how to solve the problem of excessive carbon dioxide emissions through agriculture in metropolitan areas. The results show that from 2002 to 2020 in Guangzhou, urban agricultural production decreased, the economic and social function increased, and the ecological function climbed and then declined. The carbon sequestration of urban agriculture in Guangzhou was approximately four times more than the carbon emissions. Carbon emissions experienced a process of first decreasing, then increasing, then remaining constant, and finally decreasing, while carbon sequestration first decreased and then increased. Second, the carbon emissions of urban agriculture in Guangzhou have a causal relationship with the production, social, and ecological functions. Carbon emissions are the Granger cause of the economic function but not the opposite. The carbon sequestration of urban agriculture in Guangzhou has a causal relationship with production and economic functions. Carbon sequestration is the Granger cause of the ecological function but not the opposite. There is no Granger causal relationship between carbon sequestration and the social function. Third, from 2002 to 2020, the interactive development process of urban agricultural multifunctionality and carbon effects in Guangzhou can be divided into three stages: production function oriented (2002–2006), economic and social function enhanced and production function weakened (2007–2015) and the economic and social function exceeded the production function (2016–2020). Fourth, the multifunctional transformation of urban agriculture has brought about carbon effects of reducing emissions and increasing sequestration. There is a long time lag between multifunctional transformation and carbon effects of urban agriculture.

Biochar: Production, Applications, and Market Prospects in Portugal

Biochar produced during the thermochemical decomposition of biomass is an environmentally friendly replacement for different carbon materials and can be used for carbon sequestration to mitigate climate change. In this paper, current biochar production processes and top market applications are reviewed, as well as emerging biochar uses gaining momentum in the market. Various application fields of biochar, including agricultural applications (e.g., soil conditioning), adsorption (for soil and water pollutants), carbon sequestration, catalysis, or incorporation into composites or construction materials, are also presented and discussed. According to this literature overview, slow pyrolysis is the preferred process for biochar production, whereas agricultural applications (for soil conditioning and fertilization) are the most studied and market-ready solutions for biochar use. The Alentejo region (Portugal) shows tremendous potential to be a major player in the developing biochar market considering feedstock availability and large areas for biochar agricultural application. Biochar’s production potential and possible benefits were also estimated for this Portuguese region, proving that agricultural application can effectively lead to many environmental, economic, and social gains.

Carbon sequestrating fertilizers as a tool for carbon sequestration in agriculture under aridisols

Carbon sequestrating fertilizers as a tool for carbon sequestration in agriculture under aridisols