Simulating Grazing Effects on Soil Organic Carbon Dynamics in Semi-arid Rangelands (Southern Iran)

Abstract Grazing is one of the main causes of rangeland degradation worldwide, due to the effects of overgrazing on vegetation cover and biodiversity. But few data are available on the effect of grazing intensity on the dynamics of soil organic carbon (SOC) and soil labile organic carbon (SLOC). So far, very few studies have addressed the modeling of SOC dynamics under different grazing intensities, and SLOC dynamics has not been modeled yet. In this study, we used the CENTURY model to select the most effective grazing management in terms of carbon sequestration (SOC and SLOC stocks) in semi-arid rangelands of Southern Iran. The effect of four different scenarios of grazing intensity was simulated: no grazing, light grazing (LG), moderate grazing (MG), and heavy grazing (HG). The results of long-term model simulations (2015–2100), indicated that SOC stocks will change by 2.7, 1.7, -23.4, and − 24.6% in the scenarios of exclusion, LG, MG, and HG respectively compared to 2014. With increasing grazing intensities, SLOC stocks in LG, MG, and HG scenarios significantly decreased compared to the no grazing scenario by 26.1, 59.6, and 70%, respectively. Thus, this study suggests recommending light grazing management for semi-arid rangelands of Iran and also SLOC as a suitable index for studying the effect of grazing on soil carbon.

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Effect of Grazing Management and Land Cover Types on Mineral-Associated Organic Carbon and Particulate Organic Carbon in a Semi-arid Rangelands in Kenya

10.21203/rs.3.rs-768864/v1 ◽

2021 ◽

Author(s):

Angela Nduta Gitau ◽

R.N. Onwonga ◽

J. S. Mbau ◽

J. Chepkemoi ◽

S. M. Mureithi

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Land Cover ◽

Particulate Organic Carbon ◽

Grazing Management ◽

Bare Ground ◽

Land Cover Types ◽

Continuous Grazing ◽

Arid Rangelands ◽

Semi Arid

Abstract BackgroundEnhancing soil organic carbon storage in areas under extensive livestock grazing has become a challenge in most arid and semi-arid rangelands in Sub-Saharan Africa. In Kenya for instance, continuous unplanned grazing in community lands has led to overgrazing and degradation of the rangelands. For decades, livestock production has shaped the landscape through various management practices. Grazing can be used to increase soil organic carbon (SOC) content but intensive use of land can lead to its depletion. This study was set out to elucidate the effect of two types of grazing management under varying land cover types on mineral-associated organic carbon (MAOC) and particulate organic carbon (POC) in the soil. The study was carried out in two ranches, Mpala Research Centre (controlled grazing) and Ilmotiok Community Group Ranch (continuous grazing). The experimental design was a completely randomized block design in split-plot arrangement with three replicates. The main plots were the grazing practices; (controlled grazing and continuous grazing); and sub-plots were the land cover types: (bare ground, patches of grasses, and mosaics of trees). These treatments were randomly selected and replicated three times. Three topographical positions (mid-slope, foot slope and bottom land) were used as a blocking factor.ResultsThe interaction had no significant effect on MAOC fraction in any soil depth interval. Controlled grazed zones significantly recorded higher organic carbon content (POC= 0.887% CC SD=0.49) compared to zones under continuous grazing (POC = 0.718% CC SD=0.3). Mosaic of trees (POC =1.15% CC, SD = 0.22) recorded the highest concentration of carbon followed by patches of grass (POC = 0.87% CC, SD= 0.37) and bare ground (POC = 0.38% CC SD = 0.12) had the least.ConclusionThis study shows that grazing practices as well as land cover types have a significant effect on POC but not on MAOC. Mosaic of trees under controlled grazing has higher POC whereas bareground under continuous grazing had the least POC. Destocking should be done under continuous grazed zones to reduce further loss of POC and MAOC and allow vegetation recovery.

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Sensitivity of soil organic carbon to grazing management in the semi-arid rangelands of south-eastern Australia

The Rangeland Journal ◽

10.1071/rj16020 ◽

2017 ◽

Vol 39 (2) ◽

pp. 153 ◽

Cited By ~ 8

Author(s):

S. E. Orgill ◽

C. M. Waters ◽

G. Melville ◽

I. Toole ◽

Y. Alemseged ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Ground Cover ◽

Grazing Management ◽

Woody Vegetation ◽

Soil C ◽

C Stocks ◽

Close Proximity ◽

Arid Rangelands ◽

Semi Arid

This study compared the effects of grazing management on soil organic carbon (OC) stocks in the semi-arid rangelands of New South Wales, Australia. A field survey was conducted at three locations (Brewarrina, Cobar–North and Cobar–South), with paired sites of long-term (>8 years) rotational grazing management and continuously grazed pastures (either set stocked or no stocking). At each location, soil OC, carbon (C) fractions, soil nitrogen (N) and microsite and site factors (including ground cover and woody vegetation) were measured. The control of total grazing pressure (TGP) through rotational grazing and exclusion fencing did not increase soil C stocks compared with continuous grazing for the majority of comparisons. However, in some parts of the landscape, higher soil C stock was found with TGP control, for example on the ridges (21.6 vs 13.3 t C ha–1 to 0.3 m). C stocks increased with litter and perennial ground cover and with close proximity to trees. At Brewarrina, C stocks were positively affected by perennial plant cover (P < 0.001) and litter (P < 0.05), whereas at Cobar–North and Cobar–South C stocks were positively affected by the presence of trees (P < 0.001), with higher C stocks in close proximity to trees, and with increasing litter cover (P < 0.01). The present study demonstrates that natural resource benefits, such as increased perennial cover, can be achieved through controlling TGP in the rangelands but increases in soil C may be limited in certain parts of the landscape. These findings also highlight that interactions between managed and unmanaged TGP and microsite factors, such as ground cover and proximity to woody vegetation, need to be considered when evaluating the role of changed grazing management on soil C.

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Using RothC Model to Simulate Soil Organic Carbon Stocks under Different Climate Change Scenarios for the Rangelands of the Arid Regions of Southern Iran

Water ◽

10.3390/w11102107 ◽

2019 ◽

Vol 11 (10) ◽

pp. 2107

Author(s):

Sayed Fakhreddin Afzali ◽

Bijan Azad ◽

Mohammad H. Golabi ◽

Rosa Francaviglia

Keyword(s):

Climate Change ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Climate Change Scenarios ◽

Soil Matrix ◽

Southern Iran ◽

Precipitation Decrease ◽

Rothc Model ◽

Soc Stock ◽

Arid Rangelands

Soil organic carbon (SOC) is strongly influenced by climate change, and it is believed that increased temperatures might enhance the release of CO2 with higher emission into the atmosphere. Appropriate models may be used to predict the changes of SOC stock under projected future scenarios of climate change. In this investigation, the RothC model was run for a period of 36 years under climate scenarios namely: P (no climate change) as well as CCH1 and CCH2 (climate change scenarios) in the arid rangelands of Ghir–O-Karzin’s BandBast in southern Iran. Model results have shown that after 11 years (2014–25), SOC stock decreased by 3.05% under the CCH1 scenario (with a projected annual precipitation decrease by 6.69% and mean annual temperature increase by 9.96%) and by 0.23% under the P scenario. In CCH2, with further decreases in rainfall (10.93%) and increase in temperature (12.53%) compared to CCH1, the model predicted that the SOC stock during the 25 years (2025–50) was reduced by 2.36% and 3.53% under the CCH1 and CCH2 scenario respectively. According to model predictions, with future climatic conditions (higher temperatures and lower rainfall) the decomposition rate may increase resulting in higher losses of soil organic carbon from the soil matrix. The result from this investigation may also be used for developing management techniques to be practiced in the other arid rangelands of Iran with similar conditions.

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Estimating soil organic carbon stocks using machine learning methods in the semi-arid rangelands of New South Wales

Syme, G., Hatton MacDonald, D., Fulton, B. and Piantadosi, J. (eds) MODSIM2017, 22nd International Congress on Modelling and Simulation. ◽

10.36334/modsim.2017.g1.wang ◽

2017 ◽

Keyword(s):

Machine Learning ◽

Organic Carbon ◽

Soil Organic Carbon ◽

New South ◽

Carbon Stocks ◽

Machine Learning Methods ◽

South Wales ◽

Soil Organic Carbon Stocks ◽

Arid Rangelands ◽

Semi Arid

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Estimating soil organic carbon stocks using different modelling techniques in the semi-arid rangelands of eastern Australia

Ecological Indicators ◽

10.1016/j.ecolind.2018.01.049 ◽

2018 ◽

Vol 88 ◽

pp. 425-438 ◽

Cited By ~ 44

Author(s):

Bin Wang ◽

Cathy Waters ◽

Susan Orgill ◽

Annette Cowie ◽

Anthony Clark ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Carbon Stocks ◽

Soil Organic Carbon Stocks ◽

Eastern Australia ◽

Modelling Techniques ◽

Arid Rangelands ◽

Semi Arid

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Space-time monitoring of soil organic carbon content across a semi-arid region of Australia

Geoderma Regional ◽

10.1016/j.geodrs.2021.e00367 ◽

2021 ◽

Vol 24 ◽

pp. e00367

Author(s):

Patrick Filippi ◽

Stephen R. Cattle ◽

Matthew J. Pringle ◽

Thomas F.A. Bishop

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Carbon Content ◽

Arid Region ◽

Space Time ◽

Organic Carbon Content ◽

Soil Organic Carbon Content ◽

Semi Arid Region ◽

Semi Arid

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Soil Organic Carbon Dynamics in Semi-Arid Irrigated Cropping Systems

Agronomy ◽

10.3390/agronomy11030484 ◽

2021 ◽

Vol 11 (3) ◽

pp. 484

Author(s):

Andrew M. Bierer ◽

April B. Leytem ◽

Robert S. Dungan ◽

Amber D. Moore ◽

David L. Bjorneberg

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Empirical Data ◽

Cropping Systems ◽

C Sequestration ◽

Conventional Tillage ◽

Dndc Model ◽

Application Timing ◽

Winter Triticale ◽

Semi Arid

Insufficient characterization of soil organic carbon (SOC) dynamics in semi-arid climates contributes uncertainty to SOC sequestration estimates. This study estimated changes in SOC (0–30 cm depth) due to variations in manure management, tillage regime, winter cover crop, and crop rotation in southern Idaho (USA). Empirical data were used to drive the Denitrification Decomposition (DNDC) model in a “default” and calibrated capacity and forecast SOC levels until 2050. Empirical data indicates: (i) no effect (p = 0.51) of winter triticale on SOC after 3 years; (ii) SOC accumulation (0.6 ± 0.5 Mg ha–1 year–1) under a rotation of corn-barley-alfalfax3 and no change (p = 0.905) in a rotation of wheat-potato-barley-sugarbeet; (iii) manure applied annually at rate 1X is not significantly different (p = 0.75) from biennial application at rate 2X; and (iv) no significant effect of manure application timing (p = 0.41, fall vs. spring). The DNDC model simulated empirical SOC and biomass C measurements adequately in a default capacity, yet specific issues were encountered. By 2050, model forecasting suggested: (i) triticale cover resulted in SOC accrual (0.05–0.27 Mg ha–1 year–1); (ii) when manure is applied, conventional tillage regimes are favored; and (iii) manure applied treatments accrue SOC suggesting a quadratic relationship (all R2 > 0.85 and all p < 0.0001), yet saturation behavior was not realized when extending the simulation to 2100. It is possible that under very large C inputs that C sequestration is favored by DNDC which may influence “NetZero” C initiatives.

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Effects of grazing intensity on organic carbon stock characteristics in Stipa breviflora desert steppe vegetation soil systems

The Rangeland Journal ◽

10.1071/rj16007 ◽

2017 ◽

Vol 39 (2) ◽

pp. 169 ◽

Cited By ~ 7

Author(s):

Heyun Wang ◽

Zhi Dong ◽

Jianying Guo ◽

Hongli Li ◽

Jinrong Li ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Aboveground Biomass ◽

Carbon Stock ◽

Belowground Biomass ◽

Total Carbon ◽

Desert Steppe ◽

Light Fraction Organic Carbon ◽

Grazing Intensities ◽

Organic Carbon Stock

Grassland ecosystems, an important component of the terrestrial environment, play an essential role in the global carbon cycle and balance. We considered four different grazing intensities on a Stipa breviflora desert steppe: heavy grazing (HG), moderate grazing (MG), light grazing (LG), and an area fenced to exclude livestock grazing as the Control (CK). The analyses of the aboveground biomass, litter, belowground biomass, soil organic carbon and soil light fraction organic carbon were utilised to study the organic carbon stock characteristics in the S. breviflora desert steppe under different grazing intensities. This is important to reveal the mechanisms of grazing impact on carbon processes in the desert steppe, and can provide a theoretical basis for conservation and utilisation of grassland resources. Results showed that the carbon stock was 11.98–44.51 g m–2 in aboveground biomass, 10.43–36.12 g m–2 in plant litters, and 502.30–804.31 g m–2 in belowground biomass (0–40 cm). It was significantly higher in CK than in MG and HG. The carbon stock at 0–40-cm soil depth was 7817.43–9694.16 g m–2, and it was significantly higher in LG than in CK and HG. The total carbon stock in the vegetation-soil system was 8342.14–10494.80 g m–2 under different grazing intensities, with the largest value in LG, followed by MG, CK, and HG. About 90.54–93.71% of the total carbon in grassland ecosystem was reserved in soil. The LG and MG intensities were beneficial to the accumulation of soil organic carbon stock. The soil light fraction organic carbon stock was 484.20–654.62 g m–2 and was the highest under LG intensity. The LG and MG intensities were beneficial for soil nutrient accumulation in the desert steppe.

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