Soil organic C and total N pools in the Kalahari: potential impacts of climate change on C sequestration in savannas

2014 ◽  
Vol 396 (1-2) ◽  
pp. 27-44 ◽  
Author(s):  
Kebonyethata Dintwe ◽  
Gregory S. Okin ◽  
Paolo D’Odorico ◽  
Tanja Hrast ◽  
Natalie Mladenov ◽  
...  
Keyword(s):  
Climate Change ◽  
C Sequestration ◽  
Soil Organic C ◽  
Total N ◽  
Organic C ◽  
Impacts Of Climate Change

Douglas-fir soil C and N properties a decade after termination of urea fertilization

2001 ◽  
Vol 31 (12) ◽  
pp. 2225-2236 ◽  
Author(s):  
Peter S Homann ◽  
Bruce A Caldwell ◽  
H N Chappell ◽  
Phillip Sollins ◽  
Chris W Swanston
Keyword(s):  
Mineral Soil ◽  
Cellulase Activity ◽  
Douglas Fir ◽  
Soil Organic C ◽  
Total N ◽  
Organic C ◽  
Soil C ◽  
Second Growth ◽  
Heavy Fractions ◽  
Urea Fertilization

Chemical and microbial soil properties were assessed in paired unfertilized and urea fertilized (>89 g N·m–2) plots in 13 second-growth Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stands distributed throughout western Washington and Oregon. A decade following the termination of fertilization, fertilized plots averaged 28% higher total N in the O layer than unfertilized plots, 24% higher total N in surface (0–5 cm) mineral soil, and up to four times the amount of extractable ammonium and nitrate. Decreased pH (0.2 pH units) caused by fertilization may have been due to nitrification or enhanced cation uptake. In some soil layers, fertilization decreased cellulase activity and soil respiration but increased wood decomposition. There was no effect of fertilization on concentrations of light and heavy fractions, labile carbohydrates, and phosphatase and xylanase activities. No increase in soil organic C was detected, although variability precluded observing an increase of less than ~15%. Lack of a regionwide fertilization influence on soil organic C contrasts with several site-specific forest and agricultural studies that have shown C increases resulting from fertilization. Overall, the results indicate a substantial residual influence on soil N a decade after urea fertilization but much more limited influence on soil C processes and pools.

Climate change mitigation and adaptation by biochar: mechanisms and regulatory trend in the rhizosphere

2020 ◽  
Author(s):  
Ali Feizi ◽  
Bahar Razavi
Keyword(s):  
Climate Change ◽  
Climate Change Mitigation ◽  
High Efficiency ◽  
C Sequestration ◽  
Alkaline Soil ◽  
Mitigation And Adaptation ◽  
The Impact ◽  
Change Mitigation ◽  
Biochar Amendment ◽  
Impacts Of Climate Change

<p>Climate change represents a key challenge to the sustainability of global ecosystems and human prosperity in the twenty-first century. The impacts of climate change combined with natural climate variability are predominantly adverse, and often exacerbate other environmental challenges such as degradation of ecosystems, loss of biodiversity, and air, water and land pollution. Besides, rapid industrialization and increasing adaption of agrochemical based crop production practices since green revolution have considerably increased the heavy metal contaminations in the environment.</p><p>Assessing the impacts of climate change on our planet and addressing risks and opportunities is essential for taking decisions that will remain robust under future conditions, when many climate change impacts are expected to become more significant.</p><p>Here, we established a review survey to assess the impact of biochar amendment and agroforstry system on CO<sub>2</sub> sequestration and methaloid remediation.</p><p>Our data base showed that Agroforestry-based solutions for carbon dioxide capture and sequestration for climate change mitigation and adaptation in long-term is more practical and realistic options for a sustainable ecosystem and decreasing negative effect of climate change. This was more supported in arid and semi-arid regions as well as area with saline and alkaline soil (20%).</p><p>From a soil remediation standpoint, the general trend has been shifting from reduction of the total concentration to reduction of the physic-chemically and/or biologically available fractions of metals. This regulatory shift represents a tremendous saving in remediation cost. While metals are not degradable, their speciation and binding with soil through biochar amending reduced their solubility, mobility, and bioavailability. While agroforestry showed high efficiency in C sequestration (32%), biochar amendment raveled significant mitigation in heavymetals bioavailability (42%). However, studies which coupled both approaches are limited. Thus, we conclude that combined Agroforestry and biochar amendment regulates C sequestration and metalloids remediation more efficiently.</p>

Management of sugarcane harvest residues: consequences for soil carbon and nitrogen

Soil Research ◽  
2007 ◽  
Vol 45 (1) ◽  
pp. 13 ◽  
Author(s):  
Fiona A. Robertson ◽  
Peter J. Thorburn
Keyword(s):  
Microbial Biomass ◽  
Soil Fertility ◽  
Microbial Activity ◽  
Soil N ◽  
Soil Organic C ◽  
Total N ◽  
Organic C ◽  
Soil Microbial ◽  
C And N

The Australian sugar industry is moving away from the practice of burning the crop before harvest to a system of green cane trash blanketing (GCTB). Since the residues that would have been lost in the fire are returned to the soil, nutrients and organic matter may be accumulating under trash blanketing. There is a need to know if this is the case, to better manage fertiliser inputs and maintain soil fertility. The objective of this work was to determine whether conversion from a burning to a GCTB trash management system is likely to affect soil fertility in terms of C and N. Indicators of short- and long-term soil C and N cycling were measured in 5 field experiments in contrasting climatic conditions. The effects of GCTB varied among experiments. Experiments that had been running for 1–2 years (Harwood) showed no significant trash management effects. In experiments that had been running for 3–6 years (Mackay and Tully), soil organic C and total N were up to 21% greater under trash blanketing than under burning, to 0.10 or 0.25 m depth (most of this effect being in the top 50 mm). Soil microbial activity (CO2 production) and soil microbial biomass also increased under GCTB, presumably as a consequence of the improved C availability. Most of the trash C was respired by the microbial biomass and lost from the system as CO2. The stimulation of microbial activity in these relatively short-term GCTB systems was not accompanied by increased net mineralisation of soil N, probably because of the greatly increased net immobilisation of N. It was calculated that, with standard fertiliser applications, the entire trash blanket could be decomposed without compromising the supply of N to the crop. Calculations of possible long-term effects of converting from a burnt to a GCTB production system suggested that, at the sites studied, soil organic C could increase by 8–15%, total soil N could increase by 9–24%, and inorganic soil N could increase by 37 kg/ha.year, and that it would take 20–30 years for the soils to approach this new equilibrium. The results suggest that fertiliser N application should not be reduced in the first 6 years after adoption of GCTB, but small reductions may be possible in the longer term (>15 years).

scholarly journals Assessing the response of soil carbon in Australia to changing inputs and climate using a consistent modelling framework

2021 ◽  
Vol 18 (18) ◽  
pp. 5185-5202
Author(s):  
Juhwan Lee ◽  
Raphael A. Viscarra Rossel ◽  
Mingxi Zhang ◽  
Zhongkui Luo ◽  
Ying-Ping Wang
Keyword(s):  
Global Change ◽  
Future Climate Change ◽  
Natural Environments ◽  
Soil Organic C ◽  
Total N ◽  
Organic C ◽  
Soil C ◽  
Continental Scale ◽  
Modelling Framework ◽  
C Stocks

Abstract. Land use and management practices affect the response of soil organic carbon (C) to global change. Process-based models of soil C are useful tools to simulate C dynamics, but it is important to bridge any disconnect that exists between the data used to inform the models and the processes that they depict. To minimise that disconnect, we developed a consistent modelling framework that integrates new spatially explicit soil measurements and data with the Rothamsted carbon model (Roth C) and simulates the response of soil organic C to future climate change across Australia. We compiled publicly available continental-scale datasets and pre-processed, standardised and configured them to the required spatial and temporal resolutions. We then calibrated Roth C and ran simulations to estimate the baseline soil organic C stocks and composition in the 0–0.3 m layer at 4043 sites in cropping, modified grazing, native grazing and natural environments across Australia. We used data on the C fractions, the particulate, mineral-associated and resistant organic C (POC, MAOC and ROC, respectively) to represent the three main C pools in the Roth C model's structure. The model explained 97 %–98 % of the variation in measured total organic C in soils under cropping and grazing and 65 % in soils under natural environments. We optimised the model at each site and experimented with different amounts of C inputs to simulate the potential for C accumulation under constant climate in a 100-year simulation. With an annual increase of 1 Mg C ha−1 in C inputs, the model simulated a potential soil C increase of 13.58 (interquartile range 12.19–15.80), 14.21 (12.38–16.03) and 15.57 (12.07–17.82) Mg C ha−1 under cropping, modified grazing and native grazing and 3.52 (3.15–4.09) Mg C ha−1 under natural environments. With projected future changes in climate (+1.5, 2 and 5.0 ∘C) over 100 years, the simulations showed that soils under natural environments lost the most C, between 3.1 and 4.5 Mg C ha−1, while soils under native grazing lost the least, between 0.4 and 0.7 Mg C ha−1. Soil under cropping lost between 1 and 2.7 Mg C ha−1, while those under modified grazing showed a slight increase with temperature increases of 1.5 ∘C, but with further increases of 2 and 5 ∘C the median loss of TOC was 0.28 and 3.4 Mg C ha−1, respectively. For the different land uses, the changes in the C fractions varied with changes in climate. An empirical assessment of the controls on the C change showed that climate, pH, total N, the C : N ratio and cropping were the most important controls on POC change. Clay content and climate were dominant controls on MAOC change. Consistent and explicit soil organic C simulations improve confidence in the model's estimations, facilitating the development of sustainable soil management under global change.

Simulation of soil carbon dynamics in Australia with {\sc Roth C}

2021 ◽  
Author(s):  
Raphael Viscarra Rossel ◽  
Juhwan Lee ◽  
Mingxi Zhang ◽  
Zhongkui Luo ◽  
YingPing Wang
Keyword(s):  
C:N Ratio ◽  
Clay Content ◽  
Natural Environments ◽  
Soil Organic C ◽  
Total N ◽  
Organic C ◽  
Continental Scale ◽  
C Stocks ◽  
C Decomposition ◽  
Soil Measurements

<p>We simulated soil organic carbon (C) dynamics across Australia with the Rothamsted carbon model ({\sc Roth C}) by connecting new spatially-explicit soil measurements and data with the model. This helped us to bridge the disconnection that exists between datasets used to inform the model and the processes that it depicts. We compiled publicly available continental-scale datasets and pre-processed, standardised and configured them to the required spatial and temporal resolutions. We then calibrated {\sc Roth C} and run simulations to estimate the baseline soil organic C stocks and composition in the 0--0.3~m layer at 4,043 sites in cropping, modified grazing, native grazing, and natural environments across Australia. We used data on the C fractions, the particulate, mineral associated, and resistant organic C (POC, MAOC and ROC, respectively) to represent the three main C pools in the {\sc Roth C} model's structure.<span class="Apple-converted-space">  </span>The model explained 97--98\% of the variation in measured total organic C in soils under cropping and grazing, and 65\% in soils under natural environments. We optimised the model at each site and experimented with different amounts of C inputs to simulate the potential for C accumulation under constant and chainging climate in a 100-year simulation. Soils under native grazing were the most potentially vulnerable to C decomposition and loss, while soils under natural environments were the least vulnerable. An empirical assessment of the controls on the C change showed that climate, pH, total N, the C:N ratio, and cropping were the most important controls on POC change. Clay content and climate were dominant controls on MAOC change. Consistent and explicit soil organic C simulations improve confidence in the model's estimations, contributing to the development of sustainable soil management under global change.<span class="Apple-converted-space"> </span></p>

Long-term effects of tillage, stubble, and nitrogen management on properties of a red-brown earth

1995 ◽  
Vol 35 (7) ◽  
pp. 923 ◽  
Author(s):  
NA Fettell ◽  
HS Gill
Keyword(s):  
Management Practices ◽  
Soil Organic C ◽  
Long Term Effects ◽  
Total N ◽  
Organic C ◽  
Stubble Retention ◽  
South Wales ◽  
Direct Drilling ◽  
N Management

Differences in soil organic carbon (C), total nitrogen (N), and pH resulting from 14 and 15 years of different tillage, stubble, and fertiliser N management practices were measured for a red-brown earth at Condobolin in western New South Wales. The 5 main treatments comprised stubble burning or retention in factorial combination with cultivation and direct drilling, and stubble incorporation combined with cultivation. Two rates of N fertiliser (0 and 40 or 50 kg/ha) were applied annually, and wheat was grown each year. There were no significant differences between tillage and stubble treatments for soil organic C, total N, or pH. Fertiliser N application caused small but significant increases in organic C and total N but decreased the pH of the surface 2.5 cm of soil by 0.4-0.5 units compared with the nil fertiliser rate. The study indicates that direct drilling and stubble retention with continuous wheat have had little long-term effect on soil organic C and total N in this low rainfall environment.

Simulation of soil organic carbon and nitrogen changes in cereal and pasture systems of southern Australia

Soil Research ◽  
1993 ◽  
Vol 31 (4) ◽  
pp. 481 ◽  
Author(s):  
MR Carter ◽  
WJ Parton ◽  
IC Rowland ◽  
JE Schultz ◽  
GR Steed
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Plant Biomass ◽  
Subterranean Clover ◽  
Farming Systems ◽  
Triticum Aestivum L ◽  
Soil Organic C ◽  
Total N ◽  
Organic C

Maintenance and improvement of soil organic matter levels is an important concern in dryland farming systems of temperate regions. The Century soil organic matter model was used to simulate changes in soil organic C and total N under long-term wheat (Triticum aestivum L.) and pasture rotations at five sites in southern Australia. Average declines in soil organic C and total N of 14 and 10%, respectively, in continuous and wheat-fallow systems over a 10 to 20 year period were closely simulated by the model at each site. Additions of N fertilizer (80 kg N ha-1), which prevented soil organic matter decline in continuous wheat systems, was also well represented by the model. Trends in soil organic matter under long-term legume pasture were not adequately simulated by the model, probably due to the 'annual' nature of subterranean clover (Trifolium subterranean L.) in dry seasons and subsequent changes in the ratio of live to dead plant biomass and shoot to root ratios. Overall, the study emphasizes the importance of adequate total plant C production to prevent a decline in soil organic C.

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