Sustainable alternative to biochar: Effects of oxychar on soil carbon sequestration pathway and microbial communities.

Carbon Sequestration in Soils of Latin America

Which agroforestry options give the greatest soil and above ground carbon benefits in different world regions?

PDF HTML阅读 XML下载 导出引用 引用提醒 黄土丘陵区三种典型退耕还林地土壤固碳效应差异 DOI: 10.5846/stxb201201020003 作者: 作者单位: 西北农林科技大学资源与环境学院,西北农林科技大学农学院,西北农林科技大学资源与环境学院,西北农林科技大学资源与环境学院,西北农林科技大学资源与环境学院,西北农林科技大学资源与环境学院 作者简介: 通讯作者: 中图分类号: 基金项目: 陕西省自然科学基础研究计划资助项目(2010JQ5001); 教育部高等学校博士点基金(20090204120038); 国家自然基金(30971695); 西北农林科技大学基本科研业务费专项(QN2011153); 西北农林科技大学博士启动金(2010BSJJ032) Variance analysis of soil carbon sequestration under three typical forest lands converted from farmland in a Loess Hilly Area Author: Affiliation: Northwest Agricultural & Forestry University,Northwest Agricultural & Forestry University,,,, Fund Project: 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:探讨了黄土丘陵区退耕种植10-40a的柠条、沙棘及刺槐林地土壤总有机碳库及其活性组分密度随退耕时间、土层分布及相对比例的变化差异。结果表明:100 cm深土壤碳库在退耕10a时仅柠条林地碳库未比坡耕地显著增加,但退耕20-40a 3种林地比退耕10a时都已有显著增加,且增幅均为刺槐＞沙棘＞柠条,其中总有机碳的最大增幅分别达到90.92、27.87、14.89 Mg/hm2,活性有机碳的分别达到30.28、10.51、9.67 Mg/hm2。各还林地碳库增加在退耕10a时主要来自0-40 cm浅层土,而40-100 cm深层土碳库到退耕20a起才开始显著增加。对比退耕10a时,到退耕40a时柠条、沙棘及刺槐林地0-20 cm表层土分别平均累积了35.4%、27.9%、27.1%的总有机碳,20.2%、45.1%、23.1%的活性有机碳,而20-100 cm各土层间对碳库累积比例大小变化无一致规律,平均每20 cm厚土层累积了17.4%的总有机碳和17.6%活性有机碳。并且相比坡耕地,各林地均使100 cm深土壤活性有机碳占总有机碳的比例提高,改良了碳库质量。综上分析,长期退耕下3种林地固碳效应有明显差异,以刺槐林地碳累积效应较强。 Abstract:Quantifying soil carbon sequestration may be an important consideration under large scale afforestation because it has been counted in global carbon budgets according to the Kyoto Protocol. The conversion of cropland to forest as part of a huge ecological afforestation engineering scheme has played a very important role in reversing ecological destruction in the Loess Plateau and strongly affects the carbon cycle. This research was conducted to determine the changes in total soil organic carbon and its labile fraction in soil to 100 cm under three typical forested lands. These typical forest lands are Caragana, Buckthorn, and Robinia, which have been converted from farmland between 10 and 40 years ago in a Loess Hilly Area. The results showed that, compared with sloped farmland, the concentration of total organic carbon and labile organic carbon in soil at 100 cm was not higher in Caragana forest land 10 years after conversion from farmland. The carbon pool was significantly increased in Buckthorn and Robinia after the same period. Compared with 10 years since farmland conversion, the total organic carbon and labile carbon was further increased in all forest lands after 20 to 40 years of conversion from farmland. This increase followed the order Robinia > Buckthorn > Caragana, and the highest increase in total organic carbon reached 90.92, 27.87, and 14.89 Mg/hm2, and for labile organic carbon was 30.28, 10.51, and 9.67 Mg/hm2 respectively. The changes in soil organic carbon in different soil layers were also significantly different with time since farmland conversion. The soil organic carbon and its labile fraction was increased mainly in the 0-40 cm soil layer 10 years after farmland conversion in all forest lands. The soil organic carbon pools in the 40-100 cm layer were increased significantly 20 years after farmland conversion. As a result, all soil layers showed a contribution to soil organic carbon increase with long term conversion of cropland to forest. Forty years after farmland conversion 35.4%, 27.9%, and 27.1% of the increased total organic carbon and 20.2%, 45.1%, and 23.1% of the increased labile organic carbon in the soil to 100 cm was sequestrated in the 0-20 cm layer under Caragana, Buckthorn, Robinia forest land respectively. By contrast, the proportion of soil organic carbon sequestration showed inconsistent changes among the forest lands in the 20-100 cm soil layer, with an average of 17.4% of the increased total organic carbon and 17.6% of the increased labile organic carbon sequestrated in each 20 cm layer. Additionally, in comparison with sloped farmland, the ratio of labile organic carbon to total organic carbon was significantly different in each soil layer of all forest lands 40 years after farmland conversion. This was especially so in the 60-100 cm soil layer where the ratio was increased by 146.7%, 76.9%, and 126.1% in Caragana, Buckthorn, and Robinia forest lands, respectively. The ratio in the 100 cm soil layer also increased by 63.7%, 34.0%, and 47.0% in Caragana, Buckthorn, and Robinia, respectively, which indicated the activation of soil carbon pools had been enhanced, and the quality of soil was improved indirectly. Consequently, conversion of cropland to forest could sequestrate carbon in soil and Robinia is the better forest land to improve the soil organic carbon pool. Soil carbon sequestration following the afforestation of former arable land would be a powerful carbon sink for anthropogenic CO2 production in the Loess Plateau in the future. 参考文献 相似文献 引证文献

Soils of the Sudan Savannah face severe degradation that threatens their ability to serve as soil organic carbon sinks. The impact of tree litter on soil carbon stock and carbon sequestration is essential for enhancing soil fertility, mitigating climate change effects, and sustaining agricultural productivity. Thus, on-farm field experiment was conducted near Biliya Sanda Gate, Usmanu Danfodiyo University, Sokoto, to investigate the contribution of tree canopy litter to soil carbon stock and carbon sequestration rate per year. The experiment was laid out in a Randomized Complete Block Design (RCBD) involving three treatments (Vachellia nilotica, Azadirachta indica, and open cultivated area). Soil samples were collected, prepared and analyzed for selected soil properties (Bulk density, pH and organic carbon) and soil carbon stocks and sequestration were computed using standard procedures. Data obtained was subjected to Analysis of Variance (ANOVA) and Least Significant Difference (LSD) test was used to separate significant means. Results showed that the treatments under the tree canopy significantly improved soil properties (Bulk density, pH and organic carbon), soil carbon stock and carbon sequestration rate than the open cultivated area. The soil carbon sequestration rate of the area in increasing order of the treatments was A. indica (29.03 t C ha-1 yr-1), followed by V. nilotica (20.19 t C ha-1 yr-1), and lastly the open area with the least carbon sequestration rate (11.10 t C ha-1 yr-1). The use of tree canopy in enhancing soil properties and carbon sequestration should be encouraged in the study area.

Carbon sequestration in forest soil is critical for reducing atmospheric greenhouse gas concentrations and slowing down global warming. However, little is known about the difference in soil organic carbon (SOC) among different stand ages and the relative importance of biotic and abiotic variations such as soil microbial community and soil physicochemical properties in the regulation of SOC in forests. In the present study, we measured the SOC of the topsoil (0-10 cm) in Chinese subtropical Cunninghamia lanceolata plantations of three different stand ages (young plantation of 6 years, middle-aged plantation of 12 years, and mature plantation of 25 years). We further measured microbial community composition by phospholipid fatty acid (PLFA) analysis and soil organic carbon physical fractions by wet sieving and density floating as well as other physicochemical properties. The effects of the main impact factors on SOC were investigated. The results showed that: the middle-aged plantation had significantly higher SOC (10.63 g kg−1) than the young plantation (5.33 g kg−1), and that of the mature plantation (7.83 g kg−1) was in between. Besides, the soil total PLFAs and all the functional groups (i.e., bacteria, fungi, actinomycetes, Gram-positive bacteria, and Gram-negative bacteria) of PLFAs were significantly higher in the middle-aged plantation than in the young plantation and the mature plantation. Soil physicochemical properties, including physical fractions, differed among plantations of the three stand ages. Notably, the proportion of organic carbon protected within microaggregates was significantly higher in the middle-aged plantation (40.4%) than those in the young plantation (29.2%) and the mature plantation (27.8%), indicating that the middle-aged Cunninghamia lanceolata plantation had stronger soil organic carbon stability. Both soil microbial community and physicochemical properties exerted dominant effects on SOC and jointly explained 82.7% of the variance of SOC among different stand ages. Among them, total and all the functional groups of PLFAs, nitrate nitrogen, total nitrogen, and organic carbon protected within microaggregates had a significant positive correlation with SOC. These results highlight the important role of soil biotic and abiotic factors in shaping the contents of SOC in forests of different stand ages. This study provides a theoretical basis for forestry management and forest carbon cycling models.

Soil microorganisms play pivotal roles in governing nutrient cycling, fertility maintenance, and carbon sequestration in terrestrial ecosystems. A three-year nitrogen enrichment experiment was conducted to investigate the consequences of nitrogen-induced stoichiometric imbalance on soil microbial communities in Pinus taiwanensis forests. Stoichiometric imbalance refers to a mismatch between the stoichiometry of soil nutrients and microbial biomass. Redundancy analysis (RDA) indicated that nitrogen enrichment predominantly correlates with shifts in the soil bacterial community, which are mainly associated with total soil carbon and available phosphorous. Changes in the soil microbial community were associated with the regulation of microbial biomass carbon and phosphorous. Fungal community variations were primarily influenced by increased nitrogen availability rather than soil acidification. Microbial communities influence nutrient restriction through dynamic adjustments to their structural composition. Additionally, a discernible relationship was identified between fungi and the carbon-to-nitrogen ratio of microbial biomass, as well as the carbon-to-phosphorous ratio of microbial biomass. We identified specific taxa from both Chloroflexi (bacteria) and Tremellomycetes (fungi) as biomarkers associated with specific particular nitrogen treatments. Chloroflexi establishes a specialized phosphorous-acquisition niche that not only supports its competitive survival in low-P soil environments but also facilitates its dominance in the microbial community. These biomarkers represent species with varying abundances that induce changes in microbial community structure. Notably, these taxa were identified as potential primary factors in microbial phosphorous limitation. The evidence, where vector A exceeds 45° , indicates that the soil is experiencing phosphorous limitation. Nitrogen enrichment did not exacerbate microbial carbon limitation but intensified phosphorous limitation, as evidenced by enzyme stoichiometry. These findings advance our understanding of how excess nitrogen alters soil microbial nutrient dynamics and community composition in subtropical forest ecosystems.

When the addition of nitrogen (N) fertilizer leads to increased crop biomass, it also augments carbon (C) inputs to the soil and, hence, often increases soil organic matter. Consequently, the efficient use of fertilizer N to increase crop production has also been found valuable for sequestering atmospheric carbon in soil. William H. Schlesinger, however, in his Policy Forum “Carbon sequestration in soils” (Science's Compass, 25 June 1999, p. 2095) analyzes results from a 20-year experiment in Kentucky on conventional-till and no-till corn (1) and concludes that “the full carbon cost of N fertilizer…would effectively negate any net carbon sink as a result of the application of the fertilizer.” These costs include the CO2-C emitted during fertilizer manufacture, storage, transport, and application. The three carbon cost factors (moles of CO2-C emitted per mole of N applied) documented by Schlesinger are 0.375 (stoichiometry of Haber-Bosch reaction), 0.58 (carbon cost of fertilizer manufacture) (2), and 1.436 (carbon cost of fertilizer manufacture, storage, transport, and application) (3, 4).

Soil carbon sequestration potential as affected by soil physical and climatic factors under different land uses in a semiarid region

A primary goal of low-input small-holder farming systems in the tropics is the appropriate management of organic matter (OM) turnover and nutrient cycling via adapted agricultural practices. These emphasize the promotion of soil organic matter (SOM) turnover and carbon (C) sequestration, nutrient use efficiency and soil microbial activity. Soil microbial communities are acknowledged as key players in the terrestrial C and nutrient (e.g., nitrogen (N) and phosphorus (P)) cycles. They respond sensitively to agricultural management with shifts in their community structure as well as functional properties (i.e., decomposition and mineralization). This may be in particular evident for tropical, agriculturally managed soils which show an accelerated microbial decomposition activity induced by favorable climatic and unique physicochemical soil conditions. Molecular techniques advanced the understanding about the composition of soil microbial communities and partially their functions standing in close interaction with SOM dynamics. So far, such methods have rarely been used for elucidating microbial community dynamics including composition and functioning in tropical soils under agricultural use. The primary objective of this article is thus to summarize the existing literature on tropical soil microbial ecology as drivers of OM turnover and crop nutrient supply in soils under agricultural use. This included the highlighting of the latest efforts in deploying particularly nucleic acid-based, cultivation-independent techniques to study the compositional status of soil microbial decomposer communities and, to a smaller extent, their functional attributes in response to land use change and OM management in tropical agroecosystems. The majority of available studies on tropical microbial ecology so far concentrated primarily on the description of compositional microbial community dynamics. It was, however, hardly questioned if detected structural microbial community changes substantially influenced microbial key processes which actually maintain ecosystem functioning and soil productivity. This merit remains substantially unexplored in tropical soils under agricultural use as altered microbial community compositions may be only transient with time with potentially negligible consequences on relevant microbial functioning. There are, however, a few specialized key functional microbial groups whose presence or absence may actually affect the performance, speed and recovery of important ecosystem processes including the transformation of OM and supply of crop nutrients (e.g., N and P). These may finally regulate and determine the productivity of tropical, low-input small-holder farming systems which rely essentially on indigenous soil fertility. Consequently, research recommendations are discussed with emphasis on unique characteristics of tropical environments and tropical agroecosystems to improve the current understanding about the link between microbial key players and productivity of tropical, agriculturally managed soils.

‘Deep incorporation of corn straw’ (CSDI) is to concentrate the burial of corn straw into the subsurface soil layer (20–40 cm) and to break the plough pan, thereby creating a loosened plough layer (0–20 cm) and a fertile subsurface soil layer. However, its impacts on soil organic carbon (SOC) and the microbial community remain poorly understood. A field experiment was conducted to investigate the effects of 1‐year CSDI (CD1), 3‐year CSDI (CD3) and 5‐year CSDI (CD5) on soil aggregates and aggregate‐associated SOC, as well as bacterial and fungal community characteristics (examined by the high‐throughput gene sequencing method). The results demonstrated that SOC and soil fungal diversity were decreased by CD1, but increased by CD3 and CD5. Compared with the control, CD5 promoted 2–0.25 mm soil macroaggregation, significantly increased SOC by 8.94% and aggregate‐associated SOC by 5.96%–8.84%, consequently improving the physical protection of SOC by soil aggregates. CD3 and CD5 enhanced the richness and diversity of soil bacteria and fungi, and altered community composition. For soil bacteria, the relative abundance of Acidobacteria and Chloroflexi was increased, while that of Firmicutes, Gemmatimonadetes, Sphingomonas and Bacillus was decreased. For soil fungi, the relative abundance of Ascomycota, Zygomycota, Mortierella and Fusarium was greatly improved, but that of Basidiomycota was reduced. These obvious variations in microbial community structure were beneficial to straw degradation and SOC accumulation. Overall, the optimization of microbial community with CSDI plays a positive role in promoting soil organic matter, nutrient cycling and carbon sequestration, and thus improving soil fertility.

Vegetation restoration in desert areas has an important influence on soil carbon sequestration. To understand the long‐term effects of vegetation restoration on soil particle composition and carbon sequestration of different soil particles in semi‐arid deserts, we collected the topsoil of different types of vegetation restored for different periods at the southeast margin of Mu Us Desert and analyzed the soil organic carbon (SOC) and soil inorganic carbon (SIC) contents in soil particles of different sizes. The results demonstrated that after vegetation restoration, soil particles of <0.05 mm and aggregates in arbor lands and shrub lands increased 8 and 4 times and 4.67 and 4 times than shifting sandy land (CK), respectively. The SOC and SIC in different soil particles under vegetation increased with the restoration period. Among different vegetation forms, arbor land had significant effect on SIC fixation. Soil particles of <0.05 mm contained the highest SOC and SIC contents (16.8 and 0.78 g/kg), followed by aggregates (8.26 and 6.79 g/kg), 0.05–0.25 mm (8.24 and 4.55 g/kg), and >0.25 mm (5.23 and 2.25 g/kg). As for total SOC storage, it was positively correlated with the organic carbon storage of <0.05 mm particles. We concluded that SOC and SIC of <0.05 mm soil particles and aggregates increase with the restoration period and play a leading role in soil carbon sequestration. From the perspective of long‐term soil carbon sequestration, the best vegetation restoration mode in Mu Us Desert would be arbor forest.

Soil and water conservation measures improve soil carbon sequestration and soil quality under cashews

Soil organic carbon sequestration efficiency with biochar addition across the croplands of China: A perspective from particulate and mineral-associated organic carbon.

Intensive cropping, traditional tillage practices, and crop residue removal are the major factors of soil organic carbon (SOC) depletion. Restoration of SOC levels would improve the soil’s aggregate ability, physical, chemical, and biological properties, low greenhouse gas emission, and environmental sustainability. The importance of rainfed farming in India is increasing continuously with the increasing demand for feed, fodder, and fiber. It is technologically estimated that at any point in time, 50% of cropped area in India will remain under the rainfed system. The major challenges in rainfed areas include water scarcity, climate variability, and the lack of suitable technologies and practices resulting in half of SOC being present in arid soils than in moist environments. That's why the carbon sequestration in these soils requires a wide range of management practices to restore SOC levels. Conservation agriculture (CA) practices such as minimum tillage (MT), reduced tillage (RT), and zero tillage (ZT) may help in carbon sequestration and restoring SOC levels. The results of different studies revealed that ZT, MT and RT recorded higher total organic carbon, microbial biomass carbon, and particulate organic carbon as compared with conventional tillage and these are now established methods for promoting carbon sequestration and reducing greenhouse gas emissions in soils. The continuous tillage practices are a major threat to soil health, productivity, and fertility in dry areas. The tillage technology showed direct and indirect benefits in resource-saving ability and carbon sequestration. Long-term conservation tillage, judicious nutrient, and residue management practices increase the SOC content and enhance soil aggregation, hydraulic conductivity, soil porosity, and moisture retention capacity. Generally, the soil quality index (SQI) is used as a quantitative parameter to measure the effect of crop management practices on soil health. In tropical areas, the changes in different tillage practices, input, and residue management technologies offer a conclusive statement regarding the feasibility and sustainability of CA cropping systems. The SQI indicators are highly location and purpose-specific, as directly correlated with an ecosystem, physical, chemical, and biological processes, crop management variations, and properties of soil. This review aims to highlight the impact of conservation tillage practices that have potential possibilities for carbon sequestration in soils including salt-affected soils of rainfed areas.

Management practices can have significant implications for both soil quality and carbon (C) sequestration potential in agricultural soils. Data from two long‐term trials (one at field scale and the other at lysimeter scale), underway in north‐eastern Italy, were used to evaluate the dynamics of soil organic carbon (SOC) and estimate the impact of recommended management practices (RMPs) on soil carbon sequestration. Potential SOC sequestration was calculated as the differences between the change in SOC of treatments differing only for the specified RMP for a period of at least 25 years. The trials compared the following situations: (a) improved crop rotations versus monoculture; (b) grass versus improved crop rotations; (c) residue incorporation versus residue removal; (d) high versus low rates of inorganic fertilizers; (e) integrated nutrient management/organic manures versus inorganic fertilizers. At the lysimeter scale, some of these treatments were evaluated in different soils. A general decrease in SOC (1.1 t C ha −1 year −1 ) was observed after the introduction of intensive soil tillage, evidencing both the worsening of soil quality and the contribution towards global CO 2 emissions. Initial SOC content was maintained only in permanent grassland, complex rotations and/or with the use of large quantities of livestock manure. SOC sequestration reached a maximum rate of 0.4 t C ha −1 year −1 comparing permanent grassland with an improved crop rotation. Crop residue incorporation and rates of inorganic fertilizer had less effect on SOC sequestration (0.10 and 0.038 t C ha −1 year −1 , respectively). The lysimeter experiment highlighted also the interaction between RMPs and soil type. Peaty soil tended to be a source of C independent of the amount and quality of C input, whereas a proper choice of tillage practices and organic manures enhanced SOC sequestration in a sandy soil. The most promising RMPs in the Veneto region are, therefore, conversion to grassland and use of organic manures. Although some of these RMPs are already supported by the Veneto Region Rural Development Plan, their more intensive and widespread implementation requires additional incentives to become economically feasible.