Meta‐modeling soil organic carbon sequestration potential and its application at regional scale

Feng

et al. 2017

Global Change Biology

Self Cite

371

157

Soil organic carbon (SOC) dynamics are regulated by the complex interplay of climatic, edaphic and biotic conditions. However, the interrelation of SOC and these drivers and their potential connection networks are rarely assessed quantitatively. Using observations of SOC dynamics with detailed soil properties from 90 field trials at 28 sites under different agroecosystems across the Australian cropping regions, we investigated the direct and indirect effects of climate, soil properties, carbon (C) inputs and soil C pools (a total of 17 variables) on SOC change rate (r , Mg C ha yr ). Among these variables, we found that the most influential variables on r were the average C input amount and annual precipitation, and the total SOC stock at the beginning of the trials. Overall, C inputs (including C input amount and pasture frequency in the crop rotation system) accounted for 27% of the relative influence on r , followed by climate 25% (including precipitation and temperature), soil C pools 24% (including pool size and composition) and soil properties (such as cation exchange capacity, clay content, bulk density) 24%. Path analysis identified a network of intercorrelations of climate, soil properties, C inputs and soil C pools in determining r . The direct correlation of r with climate was significantly weakened if removing the effects of soil properties and C pools, and vice versa. These results reveal the relative importance of climate, soil properties, C inputs and C pools and their complex interconnections in regulating SOC dynamics. Ignorance of the impact of changes in soil properties, C pool composition and C input (quantity and quality) on SOC dynamics is likely one of the main sources of uncertainty in SOC predictions from the process-based SOC models.

Section: Discussionsupporting

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Soil organic carbon dynamics jointly controlled by climate, carbon inputs, soil properties and soil carbon fractions

Feng

et al. 2017

Global Change Biology

Self Cite

371

157

Proc. Natl. Acad. Sci. U.S.A.

“…Therefore, our results strongly suggest that including soil food web parameters will enhance the predictive capacity of C and N cycling models. Process-based C and N cycling models require detailed input information that is often not available on regional scales (33), and general relationships between soil food web properties and processes of C and N cycling have the potential to simplify these models. Although more validation is needed (for example, within the countries and soil types sampled), the simple relationships between earthworms and CO 2 production or between AMF abundance and N leaching might help parameterize C cycling (34) and ecosystem service models (35).…”

Section: Resultsmentioning

confidence: 99%

Soil food web properties explain ecosystem services across European land use systems

Vries

Thébault

Liiri

et al. 2013

569

396

Intensive land use reduces the diversity and abundance of many soil biota, with consequences for the processes that they govern and the ecosystem services that these processes underpin. Relationships between soil biota and ecosystem processes have mostly been found in laboratory experiments and rarely are found in the field. Here, we quantified, across four countries of contrasting climatic and soil conditions in Europe, how differences in soil food web composition resulting from land use systems (intensive wheat rotation, extensive rotation, and permanent grassland) influence the functioning of soils and the ecosystem services that they deliver. Intensive wheat rotation consistently reduced the biomass of all components of the soil food web across all countries. Soil food web properties strongly and consistently predicted processes of C and N cycling across land use systems and geographic locations, and they were a better predictor of these processes than land use. Processes of carbon loss increased with soil food web properties that correlated with soil C content, such as earthworm biomass and fungal/bacterial energy channel ratio, and were greatest in permanent grassland. In contrast, processes of N cycling were explained by soil food web properties independent of land use, such as arbuscular mycorrhizal fungi and bacterial channel biomass. Our quantification of the contribution of soil organisms to processes of C and N cycling across land use systems and geographic locations shows that soil biota need to be included in C and N cycling models and highlights the need to map and conserve soil biodiversity across the world.

“…Primary productivity and SOC decomposition rates are influenced by environmental factors (i.e. initial SOC content, temperature, rainfall) and management practices such as tillage practices, fertilization, and crop rotation systems (Ransom et al, 2011;Luo et al, 2013). These factors, and their resultant influence on SOC, vary spatially (Van Der Hilst et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Sustainable limits to crop residue harvest for bioenergy: maintaining soil carbon in Australia's agricultural lands

et al. 2014

Self Cite

The use of crop residues for bioenergy production needs to be carefully assessed because of the potential negative impact on the level of soil organic carbon (SOC) stocks. The impact varies with environmental conditions and crop management practices and needs to be considered when harvesting the residue for bioenergy productions. Here, we defined the sustainable harvest limits as the maximum rates that do not diminish SOC and quantified sustainable harvest limits for wheat residue across Australia's agricultural lands. We divided the study area into 9432 climate-soil (CS) units and simulated the dynamics of SOC in a continuous wheat cropping system over 122 years (1889 -2010) using the Agricultural Production Systems sIMulator (APSIM). We simulated management practices including six fertilization rates (0, 25, 50, 75, 100, and 200 kg N ha À1 ) and five residue harvest rates (0, 25, 50, 75, and 100%). We mapped the sustainable limits for each fertilization rate and assessed the effects of fertilization and three key environmental variables -initial SOC, temperature, and precipitationon sustainable residue harvest rates. We found that, with up to 75 kg N ha À1 fertilization, up to 75% and 50% of crop residue could be sustainably harvested in south-western and south-eastern Australia, respectively. Higher fertilization rates achieved little further increase in sustainable residue harvest rates. Sustainable residue harvest rates were principally determined by climate and soil conditions, especially the initial SOC content and temperature. We conclude that environmental conditions and management practices should be considered to guide the harvest of crop residue for bioenergy production and thereby reduce greenhouse gas emissions during the life cycle of bioenergy production.