scholarly journals Soil Organic Carbon Stocks and Its Driving Factors Under Different Land-Use Patterns in Semiarid Grasslands of the Loess Plateau, China

2021 ◽  
Vol 20 (3) ◽  
Author(s):  
Hao Zhang ◽  
Jianping Li ◽  
Yi Zhang ◽  
Yutao Wang ◽  
Juan Zhang ◽  
...  
Keyword(s):  
Land Use ◽  
Arid Areas ◽  
The Loess Plateau ◽  
Soil C ◽  
C Stocks ◽  
C Stock ◽  
Semi Arid ◽  
Grazed Grassland ◽  
Soil C Stock ◽  
Topsoil Layer

Fencing for grazing exclusion and grazing are common land-use methods in the semi-arid areas of the Loess Plateau in China, which have been widely found to change grassland soil organic carbon (SOC); however empirical studies that evaluated driving factors of soil carbon (C) stocks under the different land use are still weak. In this study, we investigated soil physicochemical and soil respiration (Rs) in the fenced and grazed grassland, to study the soil C stock variations and the main driving mechanism of soil C accumulation. The results showed that bulk density (BD), soil moisture content (SMC), and soil porosity (SP) had no significant difference between fenced and grazed grassland. Fencing increased the SOC, total nitrogen (TN), and C/N ratio, and significantly increased the aboveground biomass (AGB), belowground biomass (BGB), and the amount of soil large macro-aggregates in the topsoil layer (0-10 cm), and the soil stability was improved. Meanwhile, grazing increased soil temperature (ST) and Rs. The soil C stock in the topsoil layer (0-10 cm) of fenced grassland was significantly higher than that of grazed grassland. The soil C/N ratio, BD, and MWD explained large proportions of the variations in soil C stocks. Our results indicate that fencing can improve the stability of soil structure, and reduce Rs, then increase soil C stocks, which is an effective way to improve soil C stocks of grassland ecological in semi-arid areas of northwest China.

Biochar from sugarcane residues: An overview of its sequestration potential in Sao Paulo, Brazil

2020 ◽  
Author(s):  
David Lefebvre ◽  
Jeroen Meersmans ◽  
Guy Kirk ◽  
Adrian Williams
Keyword(s):  
Soil Carbon ◽  
C Sequestration ◽  
Sao Paulo ◽  
São Paulo ◽  
Soil C ◽  
Paulo State ◽  
Sequestration Potential ◽  
C Stocks ◽  
C Stock ◽  
Soil C Stock

<p>Harvesting sugarcane (Saccharum officinarum) produces large quantities of biomass residues. We investigated the potential for converting these residues into biochar (recalcitrant carbon rich material) for soil carbon (C) sequestration. We modified a version of the RothC soil carbon model to follow changes in soil C stocks considering different amounts of fresh sugarcane residues and biochar (including recalcitrant and labile biochar fractions). We used Sao Paulo State (Brazil) as a case study due to its large sugarcane production and associated soil C sequestration potential.</p><p>Mechanical harvesting of sugarcane fields leaves behind > 10 t dry matter of trash (leaves) ha<sup>-1</sup> year<sup>-1</sup>. Although trash blanketing increases soil fertility, an excessive amount is detrimental and reduces the subsequent crop yield. After the optimal trash blanketing amount, sugarcane cultivation still produces 5.9 t C ha<sup>-1</sup> year<sup>-1</sup> of excess trash and bagasse (processing residues) which are available for subsequent use.</p><p>The available residues could produce 2.5 t of slow-pyrolysis (550°C) biochar C ha<sup>-1</sup> year<sup>-1</sup>. The model predicts this could increase sugarcane field soil C stock on average by 2.4 ± 0.4 t C ha<sup>‑1</sup> year<sup>‑1</sup>, after accounting for the climate and soil type variability across the State. Comparing different scenarios, we found that applying fresh residues into the field results in a smaller increase in soil C stock compared to the biochar because the soil C approaches a new equilibrium. For instance, adding 1.2 t of biochar C ha<sup>‑1</sup> year<sup>‑1</sup> along with 3.2 t of fresh residue C ha<sup>‑1</sup> year<sup>‑1 </sup>increased the soil C stock by 1.8 t C ha<sup>‑1</sup> year<sup>‑1 </sup>after 10 years of repeated applications. In contrast, adding 0.62 t of biochar C ha<sup>‑1</sup> year<sup>‑1</sup> with 4.5 t of fresh sugarcane residues C ha<sup>‑1</sup> year<sup>‑1 </sup>increased the soil carbon soil stock by 1.4 t C ha<sup>‑1</sup> year<sup>‑1</sup> after 10 years of application. These are reductions 25% and 40% of the potential soil C accumulation rates compared with applying available residues as biochar.   </p><p>We also tested the sensitivity of the model to biochar-induced positive priming (i.e. increased mineralization of soil organic C) using published values. This showed that the C sequestration balance remains positive over the long term, even considering an extremely high positive-priming factor. Upscaling our results to the total 5 Mha of sugarcane in Sao Paulo State, biochar application could sequester up to 50 Mt of CO<sub>2</sub> equivalent per year, representing 31% of the emissions attributed to the State in 2016.</p><p>This study provides first insights into the sequestration potential of biochar application on sugarcane fields. Measurements of changes in soil C stocks in sugarcane field experiments are needed to further validate the model, and the emissions to implement the practice at large scale need to be taken into account. As the climate crisis grows, the need for greenhouse gas removal technologies becomes crucial. Assessing the net effectiveness of readily available technologies is essential to guide policy makers.  </p>

scholarly journals A Comparison of Soil Carbon Stocks of Intact and Restored Mangrove Forests in Northern Vietnam

Forests ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 660
Author(s):  
Pham Hong Tinh ◽  
Nguyen Thi Hong Hanh ◽  
Vo Van Thanh ◽  
Mai Sy Tuan ◽  
Pham Van Quang ◽  
...  
Keyword(s):  
Soil Carbon ◽  
Mangrove Forest ◽  
Soil Core ◽  
Mangrove Forests ◽  
Soil C ◽  
Northern Vietnam ◽  
C Stocks ◽  
C Stock ◽  
Quang Ninh ◽  
Soil C Stock

Background and Objectives: In northern Vietnam, nearly 37,100 hectares of mangroves were lost from 1964–1997 due to unsustainable harvest and deforestation for the creation of shrimp aquaculture ponds. To offset these losses, efforts in the late 1990s have resulted in thousands of hectares of mangroves being restored, but few studies to date have examined how effective these efforts are at creating restored mangrove forests that function similarly to the intact mangroves they are intended to replace. Materials and Methods: We quantified and compared soil carbon (C) stocks among restored (mono and mixed species) and intact mangrove forests in the provinces of Quang Ninh, Thai Binh, Nam Dinh and Thanh Hoa in northern Vietnam. A total of 96 soil cores up to a depth of 200 cm were collected every 25 m (25, 50, 75, 100, 125, and 150 m) along 16 linear transects that were 150 m long and perpendicular to the mangrove upland interface (six cores along each transect) at Quang Ninh (four transects), Thai Binh (five), Nam Dinh (four) and Thanh Hoa (three). Five-cm-long soil samples were then collected from the 0–15 cm, 15–30 cm, 30–50 cm, 50–100 cm, and >100 cm depth intervals of each soil core. Results: The study confirmed that the soil C stock of 20–25-year-old restored mangrove forest (217.74 ± 16.82 Mg/ha) was not significantly different from that of intact mangrove forest (300.68 ± 51.61 Mg/ha) (p > 0.05). Soil C stocks of Quang Ninh (323.89 ± 28.43 Mg/ha) were not significantly different from Nam Dinh (249.81 ± 19.09 Mg/ha), but both of those were significantly larger than Thai Binh (201.42 ± 27.65 Mg/ha) and Thanh Hoa (178.98 ± 30.82 Mg/ha) (p < 0.05). Soil C stock differences among provinces could be due to their different geomorphological characteristics and mangrove age. Soil C stocks did not differ among mangroves that were restored with mixed mangrove species (289.75 ± 33.28 Mg/ha), Sonneratia caseolaris (L.) Engl. (255.67 ± 13.11 Mg/ha) or Aegiceras corniculatum (L.) Blanco (278.15 ± 43.86 Mg/ha), but soil C stocks of those mangroves were significantly greater than that of Kandelia obovata Sheue, Liu & Yong (174.04 ± 20.38 Mg/ha) (p < 0.05). Conclusion: There were significant differences in the soil C stocks of mangrove forests among species and provinces in northern Vietnam. The soil C stock of 20–25-year-old restored mangrove forest was not significantly different from that of intact mangrove forest.

scholarly journals Seasonal Soil Respiration Dynamics and Carbon-Stock Variations in Mountain Permanent Grasslands Compared to Arable Lands

Agriculture ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 165 ◽  
Author(s):  
Matteo Francioni ◽  
Paride D’Ottavio ◽  
Roberto Lai ◽  
Laura Trozzo ◽  
Katarina Budimir ◽  
...  
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Soil Respiration ◽  
Soil Temperature ◽  
Land Use Changes ◽  
Soil C ◽  
Permanent Grassland ◽  
Heterotrophic Soil Respiration ◽  
C Stock ◽  
Soil C Stock

Permanent grasslands provide a wide array of ecosystem services. Despite this, few studies have investigated grassland carbon (C) dynamics, and especially those related to the effects of land-use changes. This study aimed to determine whether the land-use change from permanent grassland to arable lands resulted in variations in the soil C stock, and whether such variations were due to increased soil respiration or to management practices. To address this, seasonal variations of soil respiration, sensitivity of soil respiration to soil temperature (Q10), and soil C stock variations generated by land-use changes were analyzed in a temperate mountain area of central Italy. The comparisons were performed for a permanent grassland and two adjacent fields, one cultivated with lentil and the other with emmer, during the 2015 crop year. Soil respiration and its heterotrophic component showed different spatial and temporal dynamics. Annual cumulative soil respiration rates were 6.05, 5.05 and 3.99 t C ha−1 year−1 for grassland, lentil and emmer, respectively. Both soil respiration and heterotrophic soil respiration were positively correlated with soil temperature at 10 cm depth. Derived Q10 values were from 2.23 to 6.05 for soil respiration, and from 1.82 to 4.06 for heterotrophic respiration. Soil C stock at over 0.2 m in depth was 93.56, 48.74 and 46.80 t C ha−1 for grassland, lentil and emmer, respectively. The land-use changes from permanent grassland to arable land lead to depletion in terms of the soil C stock due to water soil erosion. A more general evaluation appears necessary to determine the multiple effects of this land-use change at the landscape scale.

Quantifying above and belowground biomass carbon inputs for sugar-cane production in Brazil

Soil Research ◽  
2017 ◽  
Vol 55 (7) ◽  
pp. 640 ◽  
Author(s):  
A. M. Silva-Olaya ◽  
C. A. Davies ◽  
C. E. P. Cerri ◽  
D. J. Allen ◽  
F. F. C. Mello ◽  
...  
Keyword(s):  
Land Use ◽  
Belowground Biomass ◽  
First Year ◽  
Land Uses ◽  
Soil C ◽  
Sugarcane Crop ◽  
C Stocks ◽  
North Eastern ◽  
C Stock ◽  
Increasing Demand

Expansion of sugarcane crop due to the increasing demand for sugar and ethanol can affect both existing soil carbon (C) stocks, and subsequent input of new C from above and belowground biomass, influencing the overall C intensity and C payback times due to the change of land use. We present above and belowground dry biomass production, shoot-to-root ratio (S:R) as well as the net annual C inputs to the soil for sugarcane in different ratoon stages. The selected areas were as follows: (1) recently planted sugarcane area (PC), (2) first year ratoon cane (RC1) and (3) 4-year ratoon cane (RC4), which were established under Typic Quartzipsamments located in north-eastern São Paulo State. The sugarcane S:R ratios ranged from 6.6 in PC to 3.4 in RC4, and total sugarcane C inputs from 29.6 to 30.8 Mg C ha–1. The overall C balance for land use change requires effects on soil C and also C inputs from previous and future land uses. The sugarcane C input was between 3.7 and 4.0 Mg C ha–1 for each sugarcane cycle of 5 years. When accounting for soil C stock changes and aboveground biomass C losses from the prior land use, the payback times for sugarcane biofuel C debts are reduced by 3, 2 and 1 years for Cerrado wooded, Cerrado grassland and pasture conversions into sugarcane respectively.

scholarly journals The role of soil in regulation of climate

2021 ◽  
Vol 376 (1834) ◽  
pp. 20210084 ◽  
Author(s):  
Rattan Lal ◽  
Curtis Monger ◽  
Luke Nave ◽  
Pete Smith
Keyword(s):  
Land Use ◽  
Management Practices ◽  
Ghg Emissions ◽  
Organic C ◽  
Soil C ◽  
C Cycle ◽  
C Stocks ◽  
C Stock ◽  
Land Use And Management

The soil carbon (C) stock, comprising soil organic C (SOC) and soil inorganic C (SIC) and being the largest reservoir of the terrestrial biosphere, is a critical part of the global C cycle. Soil has been a source of greenhouse gases (GHGs) since the dawn of settled agriculture about 10 millenia ago. Soils of agricultural ecosystems are depleted of their SOC stocks and the magnitude of depletion is greater in those prone to accelerated erosion by water and wind and other degradation processes. Adoption of judicious land use and science-based management practices can lead to re-carbonization of depleted soils and make them a sink for atmospheric C. Soils in humid climates have potential to increase storage of SOC and those in arid and semiarid climates have potential to store both SOC and SIC. Payments to land managers for sequestration of C in soil, based on credible measurement of changes in soil C stocks at farm or landscape levels, are also important for promoting adoption of recommended land use and management practices. In conjunction with a rapid and aggressive reduction in GHG emissions across all sectors of the economy, sequestration of C in soil (and vegetation) can be an important negative emissions method for limiting global warming to 1.5 or 2°C This article is part of the theme issue ‘The role of soils in delivering Nature's Contributions to People’.

scholarly journals Effect of deforestation and subsequent land use management on soil carbon stocks in the South American Chaco

SOIL ◽  
2018 ◽  
Vol 4 (4) ◽  
pp. 251-257 ◽  
Author(s):  
Natalia Andrea Osinaga ◽  
Carina Rosa Álvarez ◽  
Miguel Angel Taboada
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Warm Season ◽  
Continuous Cropping ◽  
Soil Organic C ◽  
Organic C ◽  
Soil C ◽  
C Stocks ◽  
C Stock ◽  
The Impact

Abstract. The subhumid Chaco region of Argentina, originally covered by dry sclerophyll forest, has been subjected to clearing since the end of the 1970s and replacement of the forest by no-till farming. Land use changes produced a decrease in aboveground carbon (C) stored in forests, but little is known about the impact on soil organic C stocks. The aim of this study was to evaluate soil C stocks and C fractions up to 1 m depth in soils under different land use: <10-year continuous cropping, >20-year continuous cropping, warm-season grass pasture and native forest in 32 sites distributed over the Chaco region. The organic C stock content up to 1 m depth expressed as equivalent mass varied as follows: forest (119.3 Mg ha−1) > pasture (87.9 Mg ha−1) > continuous cropping (71.9 and 77.3 Mg ha−1), with no impact of the number of years under cropping. The coarse particle fraction (2000–212 µm) at 0–5 and 5–20 cm depth layers was the most sensitive organic carbon fraction to land use change. Resistant carbon (<53 µm) was the main organic matter fraction in all sample categories except in the forest. Organic C stock, its quality and its distribution in the profile were responsive to land use change. The conversion of the Chaco forest to crops was associated with a decrease of organic C stock up to 1 m depth and with the decrease of the labile fraction. The permanent pastures of warm-season grasses allowed higher C stocks to be sustained than cropping systems and so could be considered a sustainable land use system in terms of soil C preservation. As soil organic C losses were not restricted to the first few centimetres of the soil, the development of models that would allow the estimation of soil organic C changes in depth would be useful to evaluate the impact of land use change on C stocks with greater precision.

scholarly journals Uncertainties in the land-use flux resulting from land-use change reconstructions and gross land transitions

2017 ◽  
Vol 8 (1) ◽  
pp. 91-111 ◽  
Author(s):  
Anita D. Bayer ◽  
Mats Lindeskog ◽  
Thomas A. M. Pugh ◽  
Peter M. Anthoni ◽  
Richard Fuchs ◽  
...  
Keyword(s):  
Land Use ◽  
Agricultural Land ◽  
Land Use Changes ◽  
Terrestrial Ecosystem ◽  
Grid Cell ◽  
Carbon Stocks ◽  
Dynamic Global Vegetation Model ◽  
Soil C ◽  
Tropical Regions ◽  
C Stocks

Abstract. Land-use and land-cover (LUC) changes are a key uncertainty when attributing changes in measured atmospheric CO2 concentration to its sinks and sources and must also be much better understood to determine the possibilities for land-based climate change mitigation, especially in the light of human demand on other land-based resources. On the spatial scale typically used in terrestrial ecosystem models (0.5 or 1°) changes in LUC over time periods of a few years or more can include bidirectional changes on the sub-grid level, such as the parallel expansion and abandonment of agricultural land (e.g. in shifting cultivation) or cropland–grassland conversion (and vice versa). These complex changes between classes within a grid cell have often been neglected in previous studies, and only net changes of land between natural vegetation cover, cropland and pastures accounted for, mainly because of a lack of reliable high-resolution historical information on gross land transitions, in combination with technical limitations within the models themselves. In the present study we applied a state-of-the-art dynamic global vegetation model with a detailed representation of croplands and carbon–nitrogen dynamics to quantify the uncertainty in terrestrial ecosystem carbon stocks and fluxes arising from the choice between net and gross representations of LUC. We used three frequently applied global, one recent global and one recent European LUC datasets, two of which resolve gross land transitions, either in Europe or in certain tropical regions. When considering only net changes, land-use-transition uncertainties (expressed as 1 standard deviation around decadal means of four models) in global carbon emissions from LUC (ELUC) are ±0.19, ±0.66 and ±0.47 Pg C a−1 in the 1980s, 1990s and 2000s, respectively, or between 14 and 39 % of mean ELUC. Carbon stocks at the end of the 20th century vary by ±11 Pg C for vegetation and ±37 Pg C for soil C due to the choice of LUC reconstruction, i.e. around 3 % of the respective C pools. Accounting for sub-grid (gross) land conversions significantly increased the effect of LUC on global and European carbon stocks and fluxes, most noticeably enhancing global cumulative ELUC by 33 Pg C (1750–2014) and entailing a significant reduction in carbon stored in vegetation, although the effect on soil C stocks was limited. Simulations demonstrated that assessments of historical carbon stocks and fluxes are highly uncertain due to the choice of LUC reconstruction and that the consideration of different contrasting LUC reconstructions is needed to account for this uncertainty. The analysis of gross, in addition to net, land-use changes showed that the full complexity of gross land-use changes is required in order to accurately predict the magnitude of LUC change emissions. This introduces technical challenges to process-based models and relies on extensive information regarding historical land-use transitions.

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