Soil Carbon Sequestration Capacity Research Articles

Fate of low molecular weight organics in paddy vs. upland soil: A microbial biomarker approach

Low-molecular-weight organic carbon (LMWOC) from root exudate influences soil organic carbon cycling via priming of microbial activity. However, the mechanisms underlying the uptake and utilization of specific exudates by microorganisms in soils remain unclear. To address this gap in knowledge, a one-month 13C (0.1 mg C﹒g soil) tracer incubation study was conducted to investigate the fate of the most abundant root exudate groups (using 13C-labeled glucose, acetic acid, and oxalic acid) in paddy vs. upland soil. After 2 days of incubation, the microbial substrate use efficiency (SUE) was >80% in paddy soil, which was approximately 1.9, 2.9, and 1.3 times that in uplands with glucose, acetic acid, and oxalic acid addition, respectively. The SUE in paddy soil with glucose or acetic acid addition was always higher than that in uplands over time (P < 0.05). In both soils, the SUE of glucose was 1–4 times that of carboxylic acids (P < 0.05). The recovery of 13C-labeled total phospholipid fatty acids (PLFAs) in paddy soils was 1.5–2 times that in uplands (P < 0.05). In both soils, bacteria preferred to utilize glucose and acetic acid to synthesize cellular components. Throughout the incubation period, bacteria dominated over fungi in terms of LMWOC consumption. Gram-positive and -negative bacteria were dominant in upland and paddy soils, respectively. From days 11–30, the contribution of fungi and actinomycetes to LMWOC utilization began to appear. Temperature positively regulated 13C distribution in microbial groups (P < 0.05), and increased dissolved organic carbon in upland soil accelerated microbial SUE. The results of this study clarify microbial effects on the high soil carbon sequestration capacity of paddy soil as compared with upland in subtropical areas.

Effects of cropping patterns on the distribution, carbon contents, and nitrogen contents of aeolian sand soil aggregates in Northwest China

The long-term physicochemical responses of aeolian sandy soil aggregates to different crop rotation patterns are poorly understood. Here, we collected soil samples from the 0 to 20 cm tillage layer of continuous maize crop and alfalfa–maize rotation plots situated on the edge of the Zhangye Oasis, Northwest China. These samples were analyzed to quantify the influence of both cropping patterns on the structure, carbon content, and nitrogen content of aeolian sandy soils. When compared with long-term continuous maize cropping, planting alfalfa–maize rotation system significantly increased the mass fraction of macro-aggregates with sizes of > 2 mm and 0.25–2 mm from 8.7 to 12.1% and 19.1 to 21.2%, respectively, but decreased the mass fraction of micro-aggregates (0.053–0.25 mm) from 8.1 to 6.2%. Further, there was no significant difference in the content of silt and clay particles between each system. The alfalfa–maize rotation increased the stability of aggregates from 32 to 37%, representing an increase of 15.6%. Soil organic carbon, inorganic carbon, and total nitrogen were mainly enriched in macro-aggregates with sizes of > 2 mm, and silt and clay fractions for both cropping patterns. Implementation of a rotation pattern increased organic carbon contents by 27.2%, 25.6%, 26.7%, and 27.6%, inorganic carbon contents by 14.4%, 4.5%, 53.3%, and 21.0%, and total nitrogen contents by 29.7%, 7.0%, 4.2%, and 50.0% in aggregate particle sizes of > 2 mm, 0.25–2 mm, 0.053–0.25 mm, and < 0.053 mm, respectively, when compared to continuous maize cropping. The alfalfa–maize crop rotation can therefore effectively improve soil aggregate composition and aggregate stability, alongside organic carbon content, inorganic carbon content, total nitrogen content, and their storage capacity. This system thus represents a soil cultivation technique that can increase the soil carbon sequestration capacity in the oasis zone of Northwest China.

Soil Carbon Pool Allocation Dynamics During Soil Development in the Lower Yangtze River Alluvial Plain

The allocation dynamics of soil carbon pools during soil development and land use are the key to revealing the carbon cycle process. To clarify the distribution of the soil carbon pool and its change trend, a soil reclamation chronosequence (0 a, 60 a, 160 a, 280 a, 1 000 a, and 1 500 a reclamation) was established in a typical alluvial plain in the Lower Yangtze River, and the content and density of soil organic carbon (SOC), soil inorganic carbon (SIC), particulate organic carbon (POC), and mineral-associated organic carbon (MAOC), along with carbon sequestration potential (CSP) indicators of topsoil under different land use types were measured and analyzed. The results showed that after approximately 1 500 a reclamation, the SOC content developed from the Yangtze River alluvial deposits generally increased by 4.9% after the initial decline, whereas the SIC content decreased to 0.2% from 25.8% of the total carbon content due to its rapid leaching. The MAOC content was normally higher than that of POC, and MAOC was contributing 48.0%-79.7% of the SOC accumulation. In this region, the soil organic carbon density (SOCD) accounted for 57.4%-100% of the total carbon density, the soil carbon sequestration levels (CSL) ranged from 18.6% to 56.1%, and CSP under paddy-dryland rotation increased by 20.8% compared to that under dryland. The C/N ratio and total nitrogen content are key factors in explaining soil carbon accumulation processes, and the reclamation year plays an important role in evaluating soil carbon sequestration levels. After long-term utilization, the cultivated soil in the Yangtze River floodplain must be carefully managed through balanced fertilization to maintain soil productivity, promote the accumulation of SOC, and avoid the decline in soil carbon sequestration capacity.

CONSIDERATIONS REGARDING THE VASCULAR FLORA OF SOME FRUIT ORCHARDS IN DOLJ COUNTY, ROMANIA

Through the environmental requirement imposed by inter-rows, the eco-scheme contributes to the CAP objective of biodiversity conservation, as well as increasing the soil's carbon sequestration capacity and improving the quality of the soil structure, the main natural resource in agricultural activity. The present work aimed to analyze the vascular flora from some fruit orchards in Dolj County, Romania following a taxonomic study, starting from the need to establish a vegetal soil cover with spontaneous plants, both specific to the region and environmentally friendly. Following the observations made, it was found that the floristic composition of the grassy cover in the orchards in Dolj County is variable depending on the age of the orchard and the works that were carried out between and on the rows of trees. In orchards where human intervention is low, there is a good representation of taxa belonging to the Fabaceae family (eg Trifolium repens, T. pratense, Medicago arabica, M. sativa). On the other hand, isolated species are present in well-maintained orchards, especially from the category of weeds that can be difficult to fight (e.g. Sorghum halepense, Xanthium italicum, Conyza canadensis, etc.). Observations will be continued to consider the effect of wild plants on the environment and to establish an area-specific varietal soil cover for keeping the row spaces grass-covered.

Life Cycle-Based Carbon Emission Reduction Benefit Assessment of Centralized Photovoltaic Power Plants in China

Developing clean energy is the key to reducing greenhouse gas (GHG) emissions and addressing global climate change. Photovoltaic energy systems are considered to be clean and sustainable energy resources due to their wide distribution and easy deployment. However, the environment can still be impacted during the processes from the production to recycling of such systems. Therefore, this study was conducted based on the whole life-cycle analysis to establish a mathematical model for carbon emissions during the processes of production, transportation, and waste disposal of photovoltaic power systems. The main conclusions are as follows. (1) The carbon emissions of a centralized photovoltaic power station with a unit installed capacity of 1 kWp during its entire life cycle would be 2094.40 kg, while the carbon recycling period would last 1.89 years, which would be shorter than the expected life cycle of a photovoltaic system of 25 years, indicating significant environmental benefits. (2) The calculated results from 2022 showed that the newly constructed centralized photovoltaic power stations in China could reduce carbon dioxide emissions by 31,524.26 tons during their life cycles, and their carbon emissions from 1 kWh are approx. 1/10 of those of thermal power generation, which is significantly lower than that of thermal power generation. (3) From the perspective of the soil carbon sequestration capacity and opportunity cost, the economic cost of carbon emissions from the new centralized photovoltaic power stations in China in 2022 was 1.083 billion yuan. (4) The analysis of the relationship using the Granger causality test revealed that, with a lag of one period and a significance level of 5%, the carbon emissions from the new centralized PV power stations from 2013–2022 were the Granger cause of the added value from the secondary industry in China, while the added value from the secondary industry was not the Granger cause of the carbon emissions from the new PV power stations. The findings of the performed study could increase the utilization rate of photovoltaic energy by ensuring it is a secure sustainable low-carbon emission resource, while also reducing the impact of climate change on the planet and promoting individual well-being and social development.

Research Progress on Soil Carbon Sequestration in Dry Farmland

Dry farming is a kind of agricultural production mode widely existed in the world, and its soil carbon sequestration potential has attracted much attention. The paper discussed the influencing factors, carbon sequestration process and effect of soil carbon sequestration in dryland farmland. It was concluded that protective tillage measures such as application of organic fertilizer, no-tillage, deep tillage and straw returning could increase the carbon sequestration in surface dryland soil, biodegradable film mulching could promote soil organic carbon fixation, and rational arrangement of crops could improve soil carbon sequestration capacity.

Root biomass and altitude jointly regulate the response of topsoil organic carbon density to severe degradation of high‐altitude alpine meadows

AbstractGrassland degradation can substantially reduce soil carbon sequestration capacity. However, the effects of grassland degradation on soil organic carbon (SOC) density remain unquantified in high‐altitude alpine meadows. In this study, the response and controlling mechanisms of topsoil (0–20 cm) organic carbon were explored in a field survey involving 11 pairs of healthy versus severely degraded plots of high‐altitude (above 4000 m) alpine meadows, as well as three short‐term (3–5 years) fencing restoration projects, across the source of the Yellow River in August of 2020 and 2021. The results showed that 0–20 cm root biomass, SOC content (SCC), and density (SCD) of healthy meadows averaged 533.7 ± 291.9 g/m2 (mean ± S.D), 21.17 ± 9.36 g/kg, and 4.54 ± 1.64 kg C/m2, respectively. Root biomass, SCC, and SCD were markedly reduced by 63.0%, 33.2%, and 17.6% in severely degraded grassland compared with healthy meadows. The SCC and SCD averaged 7.92 ± 2.21 g/kg and 2.2 ± 0.9 kg C/m2 in fencing plots, respectively, and were not significantly different from severely degraded meadows, suggesting a limited improvement in SOC from short‐term fencing restoration. Analysis of a piecewise structural equation model revealed that the effect of degradation on SCD (indicated by the difference in SCD between paired healthy and degraded meadows) was jointly regulated by the differential surface root biomass and site altitude, with a total positive effect of 0.39 and 0.26, respectively. Our findings indicate the losses of topsoil organic carbon stock caused by grassland degradation are root biomass‐ and altitude‐dependent, supporting the notion that antecedent prevention of degradation, more than subsequent restoration, should be the highest priority in the adaptive management of alpine meadows in harsh high‐altitude regions.

Effects of Irrigation and Nitrogen Fertilizer on Soil Carbon Leaching in Cotton Fields in Arid Areas

In order to formulate a reasonable water input model for cotton fields in southern Xinjiang for scientific and rational fertilization, to reduce soil carbon leaching, and to improve soil carbon sequestration capacity, an undisturbed soil column leaching test was used to simulate the current field management method in the study area. Two methods, drip irrigation and flood irrigation, were set up, and three irrigation and three nitrogen fertilizer levels were used to carry out the undisturbed soil column leaching test. The results showed that the amount and mode of water and nitrogen input affected the distribution and leaching loss of organic carbon and inorganic carbon in the soil. When the nitrogen application rate increased from 270 kg·hm−2 to 450 kg·hm−2, the leaching loss of soluble organic carbon and soluble inorganic carbon increased significantly. When the water input increased from 6000 m3·hm−2 to 9000 m3·hm−2, the leaching loss of DOC and DIC increased significantly. The carbon leaching loss under drip irrigation was higher than that under flood irrigation. The leaching rates of DOC and DIC were fastest under the conditions of high water (9000 m3·hm−2) and high fertilizer (450 kg·hm−2). This shows that water and nitrogen input and irrigation methods are important factors affecting soil carbon leaching. In the case of excessive water input, long-term high-frequency irrigation is the main factor affecting carbon leaching.

Long‐term fertilization and plastic film mulching modify temporal incorporation of 13C/15N‐labelled particulate organic matter

AbstractPlastic film mulching (PFM) is critical for agricultural planting and maximizing production in semiarid and arid areas. Particulate organic matter (POM) is assumed to be a sensitive indicator for evaluating the effects of different agricultural practices on soil fertility and the soil organic carbon (SOC) pool. Soil aggregates have the function of ‘wrap’ and protect the POM stored in them. However, there is limited information regarding how PFM and fertilization jointly influence the dynamic changes of newly added stalk‐derived POM in brown earth. Consequently, an in‐depth study of the fate of carbon (C) and nitrogen (N) derived from maize stalk residues within the particulate organic carbon (POC) and particulate organic nitrogen (PON) fractions in soil aggregates was undertaken. Its outcome would contribute to better predictions on the active organic matter components sequestered in the soil. The dynamics and accumulation of newly added maize stalk C and N as POC and PON in different soil aggregates (using the dry sieving method divided into &gt;2, 1–2, 0.25–1 and &lt;0.25 mm) were analysed by an in situ 13C/15N‐tracing technique under PFM and different fertilization treatments. Over 360 days of cultivation, the POC and PON contents were significantly (p &lt; 0.05) larger in the nitrogen (N) and organic manure (M) treatments than in the MN (manure combined with nitrogen) and Control treatments. The PFM treatment accelerated the decomposition of maize stalk C in the N fertilizer treatment, with an increase of 64% in stalk‐derived POC after the 1‐day cultivation period. Stalk‐derived POM tended to accumulate in &lt;0.25 mm microaggregates in the early cultivation period and then decreased rapidly with the extension of the cultivation period affected by PFM coupled with fertilization. However, stalk‐derived POM accumulation in macroaggregates (&gt;0.25 mm) fluctuated over the 360‐day cultivation period. Accordingly, PFM application and fertilization practices had important effects on the accumulation of newly added stalk‐derived POM in soil aggregates. We conclude that the accumulation of maize residue POM was primarily affected by soil fertilization type, rather than by the presence or absence of PFM. These results provide new insights into agricultural management strategies for improving soil carbon sequestration capacity.

Veterinary Antibiotics Reduce Soil Carbon Sequestration Capacity

Livestock grazing areas sequester less carbon than those under wild herbivores.

Effects of Betula platyphylla invasion in North China on soil aggregate stability, soil organic carbon and active carbon composition of larch plantation

In order to better understand the changes of soil carbon sequestration capacity in forest after forest mixing, the effects of broadleaf tree invasion on soil aggregate stability and carbon sequestration were studied. In northern China, the pure Larix principis-rupprechtii plantations and the Larix principis-rupprechtii plantations invaded by Betula platyphylla at various degrees with the same site conditions were selected (Betula platyphylla had mixed degrees of 0.2 and 0.4). The distribution and stability of soil aggregates were analyzed, and soil organic carbon and active carbon components were determined. The distribution of soil macroaggregates (> 0.25 mm) increased with the increase in the mixed degree of Betula platyphylla. The mixture of Betula platyphylla could effectively increased SOC, EOC, DOC and MBC of the original soil and soil aggregates of different diameter classes. The invasion of Betula platyphylla had a positive indirect impact on soil carbon sequestration by affecting the soil physical and chemical properties and the aggregate stability. The invasion of Betula platyphylla had significant positive effects on soil aggregate stability, erosion resistance and soil nutrient status in Larix principis-rupprechtii plantation. Maybe the selection of suitable broadleaf mixed species can improve the soil quality and soil organic carbon sequestration of the Larix principis-rupprechtii plantation in this area.

Trade-offs between grain yields and ecological efficiencies in a wheat-maize cropping system using optimized tillage and fertilization management on the North China Plain.

Optimized fertilizer and tillage management can be an effective strategy for high ecological efficiencies as well as crop yields. The objective of this study was to assess the impact of diverse management practices on carbon footprint, and ecosystem services in a wheat-maize cropping system. An in situ field experiment field was conducted from 2018 to 2020 on the North China Plain, and six treatments were established: deep tillage (DT), shallow tillage (ST), no tillage (NT), deep tillage + adding organic fertilizer (DTF), shallow tillage + adding organic fertilizer (STF), and no tillage + adding organic fertilizer (NTF). The results showed that adding organic fertilizer and the deeper tillage depth caused higher direct CO2 and N2O emission fluxes. DTF treatment significantly increased carbon footprint either per-unit area (CFa) or per-unit net income (CFe). Compared with DT treatment, STF treatment had higher CFa but lower CFe by increasing net income through boosted crop yields. Besides, the highest ecosystem service values (ESV) were present in STF treatment during both 2years (42,017.13 CNY ha-1 and 43,352.03 CNY ha-1). In conclusion, STF treatment was an optimal management practice to trade-off grain yields and ecological efficiencies in a wheat-maize cropping system. Furthermore, this study highlights that adding organic fertilizer could be an efficient option toward sustainable farmland utilization with high soil carbon sequestration capacity and high ESV.

Ecosystem productivity has a stronger influence than soil age on surface soil carbon storage across global biomes

Interactions between soil organic matter and minerals largely govern the carbon sequestration capacity of soils. Yet, variations in the proportions of free light (unprotected) and mineral-associated (protected) carbon as soil develops in contrasting ecosystems are poorly constrained. Here, we studied 16 long-term chronosequences from six continents and found that the ecosystem type is more important than soil age (centuries to millennia) in explaining the proportion of unprotected and mineral-associated carbon fractions in surface soils across global biomes. Soil carbon pools in highly productive tropical and temperate forests were dominated by the unprotected carbon fraction and were highly vulnerable to reductions in ecosystem productivity and warming. Conversely, soil carbon in low productivity, drier and colder ecosystems was dominated by mineral-protected carbon, and was less responsive to warming. Our findings emphasize the importance of conserving ecosystem productivity to protect carbon stored in surface soils.

Effect of microplastics on CO2 emission from Yellow River Delta wetland

As natural carbon sinks, coastal wetlands are of great significance to alleviate global climate change. However, due to environmental pollution, the soil carbon sequestration capacity of coastal wetlands is decreasing, and then the emission of CO2 is accelerated. The Yellow River Delta is one of the largest deltas in China. Economic development and human activities have led to the input of large quantities of microplastics. Microplastics can alter soil properties, causing the emission of CO2 to be affected. However, the impact of common microplastics in coastal wetlands on CO2 generation and emission is not clear. In this study, tread particles (TP) and polypropylene (PP) particles were applied to coastal wetland soil to study their effects on greenhouse gas CO2 emissions. The results showed that the cumulative emission of CO2 increased by 32.7% - 49.5% and 13.9% - 24.6% respectively compared with CK 14 days after the addition of TP and PP. The promoting effect of TP was stronger than that of PP. The results provided theoretical and basic data support for the evaluation of greenhouse gas emissions and atmospheric environmental effects of Yellow River Delta wetlands under microplastics pollution.

Effect of Land Use on Plant Nutrient Availability and Soil Carbon Stock of Mokonisa Machi Watershade, Dugda Dawa Woreda, West Guji Zone, Southern Ethiopia

Background: Various land use practices have a different influence on soil degradation on both physical and chemical property of soil as well as on soil carbon sequestration capacity. A small number of studies have studied the effects of land use on plant nutrient availability and soil carbon sequestration in Ethiopia. Therefore, current study was to explore the effects of land use on vegetation nutrient accessibility and soil carbon restoration. Methods: Further definitely the study pointed out the difference between various land use category on soil texture, soil pH, available phosphorus and exchangeable potassium and the implication the farming practices on soil carbon sequestration. Soil sample were collected from the upper 0-40 cm depth of forest land, cultivated land and grazing land. The soil texture was primarily clay and heavy clay textural class. Result: Along soil depth, bulk density (BD) increasing ranges from (1.12 to 1.27 g/cm in all sampling sites. Slight increase in pH was recorded with increase in soil depth in all land use system. The average total soil organic carbon stock forest, grazing and farm land was ranged between 95.2, 88.45 and 65.5 t/ha, respectively for surface soil and 93.3, 73.75, 62.5 respectively for sub surface soil. Soil organic carbon concentration and bulk density improvement are the most important management interventions to increase soil organic carbon storage capacity.

Effects of rice stalks mulching combined with green manure (&amp;lt;italic&amp;gt;Astragalus smicus &amp;lt;/italic&amp;gt;L.) incorporated into soil and reducing nitrogen fertilizer rate on rice yield and soil fertility

<p id="C3">Planting green manure and straw retention is an effective measure to improve soil fertility. Two-year field experiment were conducted to assess the effects of reduced nitrogen rate under the rice straw mulching combined with planting green manure (<italic>Astragalus sinicus </italic>L.) at full bloom stage on rice yield, yield components, and soil nutrient availability in Hantai district, Hanzhong city, Shaanxi province from 2018 to 2020. Five treatments were assigned: (1) CK, winter fallow, no straw mulching, no fertilization; (2) NPK, winter fallow, no straw mulching, conventional nitrogen fertilizer rate; (3) GRN1, planting green manure in winter, rice straw mulching with conventional N fertilizer rate; (4) GRN2, planting green manure in winter, rice straw mulching with 80% conventional N rate; (5) GRN3, green manure planting in winter, rice straw mulching with 70% conventional N rate. The results showed that: (I) rice yield (Quanxiangyou 1521) of GRN1 was 10,047 kg hm^-2, which was higher 6.7% than that of NPK, and GRN2 and GRN3 had marginal effects in 2019. Moreover, the yield (Huanghuazhan) of GRN2 and GRN3 were significantly higher than that of NPK by 6.6% and 5.8% in 2020, respectively. Compared with CK and NPK, the rice straw mulching combined with planting green manure significantly enhanced the rice yield by 67.9%-83.0% and 2.8%-6.7%, respectively. (II) Planting green manure combined with rice straw mulching increased soil organic carbon content and available P content in 0-20 soil layer. Compared with NPK treatment, soil organic carbon and available P content of GRN2 increased 6.8%-13.2% and 9.9%-12.6%, respectively. Correlation analysis indicated that rice yield was significantly correlated with plant height, fresh weight per plant, fresh root stubble weight, filled grain number per panicle, and 1000-grain weight. Compared with NPK, GRN2 significantly increased effective panicle, effective grain number per panicle by 13.0%-29.3% and 4.5%-14.3%, respectively. Meanwhile, GRN2 significantly increased plant height, fresh weight per plant, and root fresh weight by 10.4%, 23.6%, and 30.0%, respectively. In conclusion, rice stalks mulching combined planting green manure with 20% reduced nitrogen rate can improve rice yield and agronomic performance, enlarge soil carbon sequestration capacity, and increase soil nutrients availability, which is a green rice cultural practice adapted to Hanzhong area.

植被修复初期对贵州高原喀斯特湿地湖滨带碳元素的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 植被修复初期对贵州高原喀斯特湿地湖滨带碳元素的影响 DOI: 10.5846/stxb202108302443 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 贵州省科技计划项目（黔科合基础-ZK[2021]一般099） Influence of vegetation restoration on carbon in the lakeside zone of Karst Wetland in Guizhou Plateau Author: Affiliation: Fund Project: Effects of vegetation succession on occurrence characteristics and release contributions of organic carbon: a case study at Caohai, Guizhou, SW China 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以贵州草海保护区（海拔约为2171.7 m）为研究对象，采用时空互代法研究不同地貌环境（非喀斯特地貌、喀斯特地貌及植被修复地貌）下，保护区内土壤有机碳（SOC）、易氧化有机碳（ROC）、可溶性有机碳（DOC）含量分布规律及其影响因素，以期为准确估算保护区内碳组分储量及其固碳效益评价提供科学依据。结果表明：（1）不同地貌下有机碳（SOC）含量、易氧化有机碳（ROC）和可溶性有机碳（DOC）与土层深度存在极显著负相关关系，即随土层深度增加而降低；（2）在0-50 cm土层中喀斯特地貌与非喀斯特地貌下土壤团聚体均以>0.2 mm粒级有机碳含量相对较高，<0.125 mm粒级含量最低。（3）植被恢复过程中，土壤碳组分含量显著增加，土壤固碳能力增强提高了土壤有机碳含量，促进了土壤团聚体的形成，同时也提高了土壤团聚体的稳定性。 Abstract:This paper takes Guizhou Caohai Reserve (2171.7 m above sea level approximately) as the research object, the time-space substitution method was used to study the distribution and influencing factors of soil organic carbon (SOC), easily oxidizable organic carbon (ROC) and soluble organic carbon (DOC) in different geomorphological environments (non-karst landforms, karst landforms and vegetation restoration landforms). The purpose of this paper is to provide a scientific basis for accurately estimating the reserves of carbon components and evaluating the benefits of carbon sequestration in the reserve.The results showed that:(1) The contents of SOC, ROC and DOC,under different landforms had very significantly negative correlation with soil depth, that was, they decreased with the increase of soil depth. (2) In the 0-50 cm soil layer, both karst and non-karst landforms had relatively higher organic carbon content in soil aggregates larger than 0.2 mm, and the lowest content of smaller than 0.125 mm. (3) During the process of vegetation restoration, the content of soil carbon components increased significantly, and the enhancement of soil carbon sequestration capacity increased soil organic carbon content, promoted the formation of soil aggregates, and also improved the stability of soil aggregates. 参考文献 相似文献 引证文献

Subsoil organic carbon turnover is dominantly controlled by soil properties in grasslands across China

Soil organic carbon turnover time (τ, year) is an important indicator of soil carbon stability and a major factor determining soil carbon sequestration capacity. Many previous studies have investigated τ in the topsoil layers, but little is known about subsoil τ and its environmental drivers. We estimated subsoil τ (the ratio of subsoil organic carbon (OC) stock to net primary production) using field observations from the published literatures and employed regression analysis and the structural equation model (SEM) to identify the effects of climate, soil, and vegetation variables on subsoil τ in China’s grasslands. The results showed that the average subsoil τ over 0.2–1 m varied greatly from 5.5 to 702.2 years, with a mean (±standard deviation) of 118.5 ± 97.8 years. Subsoil τ varied significantly among different grassland types, with 164.0 ± 112.0 years for alpine meadow, 107.0 ± 47.9 years for alpine steppe, 177.0 ± 143.0 years for temperate desert steppe, 96.6 ± 88.7 years for temperate meadow steppe, and 101.0 ± 75.9 years for temperate typical steppe. Subsoil τ was significantly negatively correlated (p < 0.05) with normalized difference vegetation index, leaf area index, and gross primary production. Mean annual (air) temperature and precipitation had a negative impact on τ, indicating a faster turnover of soil carbon with a changing climate. Based on SEM, soil properties mainly drove subsoil τ, challenging our current understanding and providing evidence that different factors control topsoil and subsoil τ. In this sense, different environmental factors should be considered to reliably predict soil carbon dynamics at the top of 1 m and subsoils in biogeochemical models or Earth system models at regional or global scales.

Effects of tillage managements on soil microbial community structure in soil aggregates of fluvo-aquic soil

In order to explore the impacts of different tillage managements on the structure and diversity of microbial community in fluvo-aquic soil, the phospholipid fatty acid (PLFA) method was used to determine microbial community composition in soil aggregates. Four tillage treatments were set up in Qihe County, Shandong Province, including rotary tillage with straw return (RT), deep ploughing with straw return (DP), subsoiling with straw return (SS) and no-tillage with straw return (NT). Our results showed that DP treatment significantly increased the amount of fungal PLFAs and fungi/bacteria ratio in >5 mm soil aggregates compared with RT. DP could provide favorable conditions for fungi reproduction, facilitate soil organic matter storage and soil buffering capacity. DP increased the amount of PLFAs in 5-2 mm soil aggregates, reduced the gram-positive (G+) /gram-negative (G-) bacteria ratio in the soil, and improved soil nutritional status. In addition, DP improved the microbial abundance index in <0.25 mm soil aggregates. In general, DP could not only increase the abundance of bacteria and fungi in soil aggregates, but also improve the microbial community structure of soil aggregate, which help increase soil carbon sequestration capacity and keep soil microbial diversity to a certain extent. Results of the redundancy analysis showed that the total PLFAs, PLFAs of bacteria, G- bacteria and actinomycetes in soil aggregates are closely correlated with soil organic carbon, while PLFAs of G+ bacteria had a strong correlation with soil total nitrogen concentration. In each treatment, microbial communities in larger sizes of soil aggregates were mainly affected by the ratio of organic carbon to total nitrogen, soil moisture, pH, and mass fractions of soil aggregates, while the microbial communities in smaller sizes of soil aggregates were affected by the concentrations of organic carbon and total nitrogen.

Soil extracellular oxidases mediated nitrogen fertilization effects on soil organic carbon sequestration in bioenergy croplands

AbstractNitrogen (N) fertilization significantly affects soil extracellular oxidases, agents responsible for decomposition of slow turnover and recalcitrant soil organic carbon (SOC; e.g., lignin), and consequently influences soil carbon sequestration capacity. However, it remains unclear how soil oxidases mediate SOC sequestration under N fertilization, and whether these effects co‐vary with plant type (e.g., bioenergy crop species). Using a spatially explicit design and intensive soil sampling strategy under three fertilization treatments in switchgrass (SG: Panicum virgatum L.) and gamagrass (GG: Tripsacum dactyloides L.) croplands, we quantified the activities of polyphenolic oxidase (PHO), peroxidase (PER), and their sum associated with recalcitrant C acquisition (OX). The fertilization treatments included no N fertilizer input (NN), low N input (LN: 84 kg N ha−1 year−1 in urea), and high N input (HN: 168 kg N ha−1 year−1 in urea). Besides correlations between soil oxidases and SOC (formerly published), both descriptive and geostatistical approaches were applied to evaluate the effects of N fertilization and crop type on soil oxidases activities and their spatial distributions. Results showed significantly negative correlations between soil oxidase activities and SOC across all treatments. The negative relationship of soil oxidases and SOC was also evident under N fertilization. First, LN significantly depressed oxidases in both mean activities and spatial heterogeneity, which corresponded to increased SOC in SG (though by 5.4%). LN slightly influenced oxidases activities and their spatial heterogeneity, consistent with insignificant changes of SOC in GG. Second, HN showed trends of decrease in soil oxidase activities, which aligned with the significantly enhanced SOC in both croplands. Overall, this study demonstrated that soil oxidase activities acted as sensitive and negative mediators of SOC sequestration in bioenergy croplands and optimizing fertilizer use particularly in switchgrass cropland can improve for both carbon sequestration and environmental benefit.