scholarly journals Supplementary material to "Modification of the RothC model to simulate soil C mineralization of exogenous organic matter"

Author(s):  
Claudio Mondini ◽  
Maria Luz Cayuela ◽  
Tania Sinicco ◽  
Flavio Fornasier ◽  
Antonia Galvez ◽  
...  
2017 ◽  
Author(s):  
Claudio Mondini ◽  
Maria Luz Cayuela ◽  
Tania Sinicco ◽  
Flavio Fornasier ◽  
Antonia Galvez ◽  
...  

Abstract. The development of soil organic C (SOC) models capable to produce accurate predictions of the long term decomposition of exogenous organic matter (EOM) in soils is important for an effective management of organic amendments. However, reliable C modelling in amended soils requires specific optimization of current C models to take into account the high variability of EOM origin and properties. The aim of this work was to improve the prediction of C mineralization rates in amended soils by modifying the RothC model to encompass a better description of EOM quality. The standard RothC model, involving C input to the soil only as decomposable (DPM) or resistant (RPM) organic material, was modified by introducing additional pools of decomposable (DEOM), resistant (REOM) and humified (HEOM) EOM. The partitioning factors and decomposition rates of the additional EOM pools were estimated by model fitting to respiratory curves of amended soils. For this task, 30 EOMs from 8 contrasting groups (compost, anaerobic digestates, sewage sludges, agro-industrial wastes, crop residues, bioenergy by-products, animal residues, meat and bone meals), were added to 10 soils and incubated under different conditions. The modified Roth C model was fitted to C mineralization curves in amended soils with great accuracy (mean correlation coefficient: 0.995). Differently to the standard model, the EOM-optimized RothC was able to better accommodate the large variability in EOM source and composition, as indicated by the decrease in the root mean squared error of the simulations for different EOMs (from 29.9 % to 3.7 % and from 20.0 % to 2.5 % for bioethanol residue and household waste compost amended soils, respectively). Average decomposition rates for DEOM and REOM pools were 89 y−1 and 0.4 y−1, higher than the standard model coefficients for DPM (10 y−1) and RPM (0.3 y−1). Results indicate that explicit treatment of EOM heterogeneity enhances the model ability to describe amendment decomposition under laboratory conditions and provides useful information to improve C modelling on the effects of different EOM on C dynamics in agricultural soils. Future researches involve the validation of the modified model with field data and its application to long term simulation of SOC patterns in amended soil at regional scale under climate change.


2014 ◽  
Vol 44 (5) ◽  
pp. 441-448 ◽  
Author(s):  
Kai Yang ◽  
Jiaojun Zhu ◽  
Shuang Xu

Soil organic matter decomposition, a major process that affects soil carbon (C) storage, is controlled by the available nitrogen (N) in soils. However, little is known about the effects of the various forms of N input on organic matter decomposition in typical temperate forest types such as secondary forests and larch plantations. A 56-day laboratory incubation experiment was performed to determine the effects of dominant N forms (ammonium dominant = NH4+; ammonium nitrate dominant = NH4NO3; and nitrate dominant = NO3−) and four N levels (control = no N added; low N = 25 mg N·kg soil−1; medium N = 50 mg N·kg soil−1; and high N = 75 mg N·kg soil−1) on soil C mineralization in secondary forest and larch plantation soils. The results indicated that the addition of N inhibits C mineralization, regardless of the form of N applied in the secondary forest soil, whereas NH4+-dominant soil decreased C mineralization in the larch plantation soil. Furthermore, among the various forms of N, the addition of NH4+ reduced C mineralization the most compared with NO3– and NH4NO3 additions in the secondary forest soil. Additional N generally suppressed phenol oxidase activity but had no effects on activities of exoglucanase, β-glucosidase, and N-acetyl-β-glucosaminidase or soluble organic C in the secondary forest soil. The decrease in phenol oxidase activity that was associated with the addition of N is likely to have an effect on soil C mineralization. We also observed that soil pH decreased with the increasing rate of N input in the secondary forest soil, which indicates that soil C mineralization may be sensitive to the amount of N through changes in soil pH. Overall, the addition of N resulted in changes in soil C mineralization that depended on the form of the N input and the forest type. The application of NH4+-dominant N influenced soil C dynamics in the secondary forest and larch plantation soils in this short-term experiment.


2017 ◽  
Vol 14 (13) ◽  
pp. 3253-3274 ◽  
Author(s):  
Claudio Mondini ◽  
Maria Luz Cayuela ◽  
Tania Sinicco ◽  
Flavio Fornasier ◽  
Antonia Galvez ◽  
...  

Abstract. The development of soil organic C (SOC) models capable of producing accurate predictions for the long-term decomposition of exogenous organic matter (EOM) in soils is important for the effective management of organic amendments. However, reliable C modeling in amended soils requires specific optimization of current C models to take into account the high variability in EOM origin and properties. The aim of this work was to improve the prediction of C mineralization rates in amended soils by modifying the RothC model to encompass a better description of EOM quality. The standard RothC model, involving C input to the soil only as decomposable (DPM) or resistant (RPM) organic material, was modified by introducing additional pools of decomposable (DEOM), resistant (REOM) and humified (HEOM) EOM. The partitioning factors and decomposition rates of the additional EOM pools were estimated by model fitting to the respiratory curves of amended soils. For this task, 30 EOMs from 8 contrasting groups (compost, anaerobic digestates, sewage sludge, agro-industrial waste, crop residues, bioenergy by-products, animal residues and meat and bone meals) were added to 10 soils and incubated under different conditions. The modified RothC model was fitted to C mineralization curves in amended soils with great accuracy (mean correlation coefficient 0.995). In contrast to the standard model, the EOM-optimized RothC was able to better accommodate the large variability in EOM source and composition, as indicated by the decrease in the root mean square error of the simulations for different EOMs (from 29.9 to 3.7 % and 20.0 to 2.5 % for soils amended with bioethanol residue and household waste compost, respectively). The average decomposition rates for DEOM and REOM pools were 89 and 0.4 yr−1, higher than the standard model coefficients for DPM (10 yr−1) and RPM (0.3 yr−1). The results indicate that the explicit treatment of EOM heterogeneity enhances the model ability to describe amendment decomposition under laboratory conditions and provides useful information to improve C modeling on the effects of different EOM on C dynamics in agricultural soils. Future research will involve the validation of the modified model with field data and its application in the long-term simulation of SOC patterns in amended soil at regional scales under climate change.


2015 ◽  
Vol 35 (24) ◽  
Author(s):  
万菁娟 WAN Jingjuan ◽  
郭剑芬 GUO Jianfen ◽  
刘小飞 LIU Xiaofei ◽  
纪淑蓉 JI Shurong ◽  
任卫岭 REN Weiling ◽  
...  

2005 ◽  
Vol 2 (1) ◽  
pp. 203-238 ◽  
Author(s):  
D. Huygens ◽  
P. Boeckx ◽  
O. Van Cleemput ◽  
R Godoy ◽  
C. Oyarzún

Abstract. The extreme vulnerability of soil organic carbon to climate and land use change emphasizes the need for further research in different terrestrial ecosystems. We have studied the aggregate stability and carbon dynamics in a chronosequence of three different land uses in a south Chilean Andisols: a second growth Nothofagus obliqua forest (SGFOR), a grassland (GRASS) and a Pinus radiata plantation (PINUS). The aim of this study was to investigate the role of Al as soil organic matter stabilizing agent in this Andisol. In a case study, we linked differences in carbon dynamics between the three land use treatments to physical protection and recalcitrance of the soil organic matter (SOM). In this study, C aggregate stability and dynamics were studied using size and density fractionation experiments of the SOM, δ13C and total carbon analysis of the different SOM fractions, and mineralization measurements. The results showed that electrostatic attractions between and among Al-oxides and clay minerals are mainly responsible for the stabilization of soil aggregates and the physical protection of the enclosed soil organic carbon. Whole soil C mineralization rate constants were highest for SGFOR and PINUS, followed by GRASS. In contrast, incubation experiments of isolated macro organic matter fractions showed that the recalcitrance of the SOM decreased in another order: PINUS > SGFOR > GRASS. We concluded that physical protection of soil aggregates was the main process determining whole soil C mineralization. Land use changes affected soil organic carbon dynamics in this south Chilean Andisol by altering soil pH and consequently available Al.


1999 ◽  
Vol 79 (4) ◽  
pp. 521-528 ◽  
Author(s):  
A. J. Franzluebbers ◽  
R. L. Haney ◽  
F. M. Hons ◽  
D. A. Zuberer

Microbial biomass, as part of the active pool of soil organic matter, is critical in decomposition of organic materials, nutrient cycling, and formation of soil structure. We evaluated chloroform fumigation-incubation with subtraction of a control (CFI/F–C) and without subtraction of a control (CFI/F) as methods to assess biological soil quality. Relationships between CFI/F and potential C mineralization, particulate organic C, and soil organic C were stronger (r2 = 0.86 ± 0.07, n = 232) than those between CFI/F–C and the same soil C pools (r2 = 0.25 ± 0.09) in soils from Georgia. From published data, relationships of CFI/F with potential C mineralization and soil organic C were stronger than those of chloroform fumigation-extraction and substrate-induced respiration with these soil C pools. Effects of land management on biological soil quality using CFI/F were consistent with those determined using other soil C pools as response variables. However, land management effects on biological soil quality using CFI/F–C were either contrary to those using other soil C pools or not detectable because of greater inherent variability in CFI/F–C. Chloroform fumigation-incubation without subtraction of a control is a robust and reliable method to assess biological soil quality under a wide range of soil conditions. Key words: Active soil carbon, chloroform fumigation-extraction, microbial biomass, soil organic matter, soil quality, substrate-induced respiration


Author(s):  
S.M. Thomas ◽  
M.H.Beare C.D. Ford ◽  
V. Rietveld

Humping/hollowing and flipping are land development practices widely used on the West Coast to overcome waterlogging constraints to pasture production. However, there is very limited information about how the resulting "new" soils function and how their properties change over time following these extreme modifications. We hypothesised that soil quality will improve in response to organic matter inputs from plants and excreta, which will in turn increase nutrient availability. We tested this hypothesis by quantifying the soil organic matter and nutrient content of soils at different stages of development after modification. We observed improvements in soil quality with increasing time following soil modification under both land development practices. Total soil C and N values were very low following flipping, but over 8 years these values had increased nearly five-fold. Other indicators of organic matter quality such as hot water extractable C (HWC) and anaerobically mineralisable N (AMN) showed similar increases. With large capital applications of superphosphate fertiliser to flipped soils in the first year and regular applications of maintenance fertiliser, Olsen P levels also increased from values


2014 ◽  
Vol 37 (11) ◽  
pp. 988-997 ◽  
Author(s):  
Li XU ◽  
Shu-Xia YU ◽  
Nian-Peng HE ◽  
Xue-Fa WEN ◽  
Pei-Li SHI ◽  
...  

2012 ◽  
Vol 42 (11) ◽  
pp. 1953-1964 ◽  
Author(s):  
Irene Fernandez ◽  
Juan Gabriel Álvarez-González ◽  
Beatríz Carrasco ◽  
Ana Daría Ruíz-González ◽  
Ana Cabaneiro

Forest ecosystems can act as C sinks, thus absorbing a high percentage of atmospheric CO2. Appropriate silvicultural regimes can therefore be applied as useful tools in climate change mitigation strategies. The present study analyzed the temporal changes in the effects of thinning on soil organic matter (SOM) dynamics and on soil CO2 emissions in radiata pine ( Pinus radiata D. Don) forests. Soil C effluxes were monitored over a period of 2 years in thinned and unthinned plots. In addition, soil samples from the plots were analyzed by solid-state 13C-NMR to determine the post-thinning SOM composition and fresh soil samples were incubated under laboratory conditions to determine their biodegradability. The results indicate that the potential soil C mineralization largely depends on the proportion of alkyl-C and N-alkyl-C functional groups in the SOM and on the microbial accessibility of the recalcitrant organic pool. Soil CO2 effluxes varied widely between seasons and increased exponentially with soil heating. Thinning led to decreased soil respiration and attenuation of the seasonal fluctuations. These effects were observed for up to 20 months after thinning, although they disappeared thereafter. Thus, moderate thinning caused enduring changes to the SOM composition and appeared to have temporary effects on the C storage capacity of forest soils, which is a critical aspect under the current climatic change scenario.


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