Is the operationally defined fraction of soil organic matter, “GRSP” (glomalin-related soil protein), stable in soils? Evidence from trends in long-term bare fallow soil

2020 ◽  
Author(s):  
Gaoussou Cissé ◽  
Folkert van Oort ◽  
Claire Chenu ◽  
Marc Essi ◽  
Siobhan Staunton
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Fallow Soil ◽  
Bare Fallow ◽  
Soil Protein

scholarly journals Priming and substrate quality interactions in soil organic matter models

2013 ◽  
Vol 10 (3) ◽  
pp. 2089-2103 ◽  
Author(s):  
T. Wutzler ◽  
M. Reichstein
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Balance Model ◽  
Levels Of Abstraction ◽  
Substrate Quality ◽  
Substrate Limitation ◽  
Energy Limitation ◽  
Bare Fallow ◽  
Different Levels

Abstract. Interactions between different qualities of soil organic matter (SOM) affecting their turnover are rarely represented in models. In this study, we propose three mathematical strategies at different levels of abstraction to represent those interactions. By implementing these strategies into the Introductory Carbon Balance Model (ICBM) and applying them to several scenarios of litter input, we show that the different levels of abstraction are applicable at different timescales. We present a simple one-parameter equation of substrate limitation that can straightforwardly be implemented into other models of SOM dynamics at decadal timescale. The study demonstrates how substrate quality interactions can explain patterns of priming effects, accelerate turnover in FACE experiments, and the slowdown of decomposition in long-term bare fallow experiments as an effect of energy limitation of microbial biomass. The mechanisms of those interactions need to be further scrutinized empirically for a more complete understanding. Overall, substrate quality interactions contribute to both understanding and quantitatively modelling SOM dynamics.

Carbon saturation drives spatial patterns of soil organic matter losses under long-term bare fallow

Geoderma ◽  
2017 ◽  
Vol 306 ◽  
pp. 89-98 ◽  
Author(s):  
N. Meyer ◽  
L. Bornemann ◽  
G. Welp ◽  
H. Schiedung ◽  
M. Herbst ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Spatial Patterns ◽  
Carbon Saturation ◽  
Bare Fallow

scholarly journals Priming and substrate quality interactions in soil organic matter models

2012 ◽  
Vol 9 (12) ◽  
pp. 17167-17201 ◽  
Author(s):  
T. Wutzler ◽  
M. Reichstein
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Balance Model ◽  
Levels Of Abstraction ◽  
Decadal Time Scale ◽  
Substrate Quality ◽  
Energy Limitation ◽  
Bare Fallow ◽  
Different Levels

Abstract. Interactions between different qualities of soil organic matter (SOM) affecting their turnover are rarely represented in models. In this study we propose three mathematical strategies at different levels of abstraction for representing those interactions. Implementing these strategies into the Introductory Carbon Balance Model (ICBM) and applying them to several scenarios of litter input show that the different levels of abstraction are applicable on different time scales. We present a simple one-parameter equation of substrate limitation applicable at decadal time scale that is straightforward to implement into other models of SOM dynamics. We show how substrate quality interactions can explain priming effects, acceleration of turnover times in FACE experiments, and the slowdown of decomposition in long-term bare fallow experiments as an effect of energy limitation of microbial biomass. The mechanisms of those interactions need to be further scrutinized empirically for a more complete understanding. Overall, substrate quality interactions offer a valuable way of understanding and quantitatively modelling SOM dynamics.

scholarly journals Multidecadal persistence of organic matter in soils: investigations at the submicrometer scale

2018 ◽  
Author(s):  
Suzanne Lutfalla ◽  
Pierre Barré ◽  
Sylvain Bernard ◽  
Corentin Le Guillou ◽  
Julien Alléon ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Coarse Silt ◽  
Fine Silt ◽  
Mineral Matrix ◽  
Bare Fallow

Abstract. The mineral matrix, particularly clay-sized minerals, protects soil organic matter (SOM) from decomposition by microorganisms. Here we report the characterization of SOM and associated minerals over decades of biodegradation, in a French long-term bare fallow (LTBF) experiment started in 1928. The amounts of carbon (C) and nitrogen (N) declined with time for six fractions (sand, coarse silt, fine silt, coarse clays, intermediate clays and fine clays). The C : N ratios of SOM associated to silt fractions remained constant whereas they significantly decreased in clays, reaching very low values in intermediate and fine clays (C : N 

scholarly journals Long-Term Bare Fallow Soil Reveals The Temperature Sensitivity of Priming Effect of The Relatively Stabilized Soil Organic Matter

2021 ◽  
Author(s):  
Xiuwei Zhang ◽  
Biao Zhu ◽  
Feihai Yu ◽  
Peng Wang ◽  
Weixin Cheng
Keyword(s):  
Organic Matter ◽  
Priming Effect ◽  
Field Soil ◽  
Old Field ◽  
Maize Leaves ◽  
Fallow Soil ◽  
Bare Fallow ◽  
Som Decomposition ◽  
Microbial N

Abstract Priming plays an important role in modifying the decomposition of soil organic matter (SOM), but there are large uncertainties in the temperature effect on priming mainly due to the variation in SOM stability. Long-term bare fallow offers a unique opportunity to isolate the relatively stabilized SOM pool and study its properties. We tested the temperature effect on priming of the relatively stabilized SOM pool by incubating soil samples collected from a bare fallow (representing the relatively stabilized SOM) and its adjacent old field (containing both stabilized SOM and labile SOM) at 10 and 20°C for 815 days. We amended the soil samples with C4 maize leaves to distinguish the CO2 source released from the soils (formed under C3 vegetation) and the substrate added (i.e. maize leaves) based on the natural abundance of δ13C. In all cases, there was a positive priming effect on native SOM decomposition when fresh organic matter (maize leaves) was added. The temperature sensitivity of priming effect (calculated as the difference in SOM decomposition due to the addition of maize leaves) in the bare fallow soil and the old field soil was quite different: increasing temperature significantly enhanced the magnitude of priming effect in the bare fallow soil, whereas had no effect on the magnitude of priming effect in the old field soil. The increase of the amount of microbial biomass C by maize leaves application was higher in the bare fallow soil than in the old field soil. Furthermore, for maize leaves-treated soil, temperature increase significantly increased the rate of microbial N mining throughout the incubation in the bare fallow soil, but had minor effect on microbial N mining in the old field soil at the end of incubation. We conclude that the priming effect of the relatively stabilized SOM was sensitive to temperature increase, which may be mainly driven by greater microbial growth and microbial demand for N. This work highlights the vulnerability of stabilized SOM to priming effect under global warming and reveals the potential role of microbes in regulating soil C dynamics under future climate change.

scholarly journals DRIFTS band areas as measured pool size proxy to reduce parameter uncertainty in soil organic matter models

2020 ◽  
Vol 17 (6) ◽  
pp. 1393-1413 ◽  
Author(s):  
Moritz Laub ◽  
Michael Scott Demyan ◽  
Yvonne Funkuin Nkwain ◽  
Sergey Blagodatsky ◽  
Thomas Kätterer ◽  
...  
Keyword(s):  
Organic Matter ◽  
Steady State ◽  
Soil Organic Matter ◽  
Absorption Band ◽  
Parameter Uncertainty ◽  
Turnover Rates ◽  
Bayesian Calibration ◽  
Individual Site ◽  
Bare Fallow

Abstract. Soil organic matter (SOM) turnover models predict changes in SOM due to management and environmental factors. Their initialization remains challenging as partitioning of SOM into different hypothetical pools is intrinsically linked to model assumptions. Diffuse reflectance mid-infrared Fourier transform spectroscopy (DRIFTS) provides information on SOM quality and could yield a measurable pool-partitioning proxy for SOM. This study tested DRIFTS-derived SOM pool partitioning using the Daisy model. The DRIFTS stability index (DSI) of bulk soil samples was defined as the ratio of the area below the aliphatic absorption band (2930 cm−1) to the area below the aromatic–carboxylate absorption band (1620 cm−1). For pool partitioning, the DSI (2930 cm−1 ∕ 1620 cm−1) was set equal to the ratio of fast-cycling ∕ slow-cycling SOM. Performance was tested by simulating long-term bare fallow plots from the Bad Lauchstädt extreme farmyard manure experiment in Germany (Chernozem, 25 years), the Ultuna continuous soil organic matter field experiment in Sweden (Cambisol, 50 years), and 7 year duration bare fallow plots from the Kraichgau and Swabian Jura regions in southwest Germany (Luvisols). All experiments were at sites that were agricultural fields for centuries before fallow establishment, so classical theory would suggest that a steady state can be assumed for initializing SOM pools. Hence, steady-state and DSI initializations were compared, using two published parameter sets that differed in turnover rates and humification efficiency. Initialization using the DSI significantly reduced Daisy model error for total soil organic carbon and microbial carbon in cases where assuming a steady state had poor model performance. This was irrespective of the parameter set, but faster turnover performed better for all sites except for Bad Lauchstädt. These results suggest that soils, although under long-term agricultural use, were not necessarily at a steady state. In a next step, Bayesian-calibration-inferred best-fitting turnover rates for Daisy using the DSI were evaluated for each individual site or for all sites combined. Two approaches significantly reduced parameter uncertainty and equifinality in Bayesian calibrations: (1) adding physicochemical meaning with the DSI (for humification efficiency and slow SOM turnover) and (2) combining all sites (for all parameters). Individual-site-derived turnover rates were strongly site specific. The Bayesian calibration combining all sites suggested a potential for rapid SOM loss with 95 % credibility intervals for the slow SOM pools' half-life being 278 to 1095 years (highest probability density at 426 years). The credibility intervals of this study were consistent with several recently published Bayesian calibrations of similar two-pool SOM models, i.e., with turnover rates being faster than earlier model calibrations suggested; hence they likely underestimated potential SOM losses.

scholarly journals DRIFTS peaks as measured pool size proxy to reduce parameter uncertainty of soil organic matter models

2019 ◽  
Author(s):  
Moritz Laub ◽  
Michael Scott Demyan ◽  
Yvonne Funkuin Nkwain ◽  
Sergey Blagodatsky ◽  
Thomas Kätterer ◽  
...  
Keyword(s):  
Organic Matter ◽  
Steady State ◽  
Soil Organic Matter ◽  
Parameter Uncertainty ◽  
Stability Index ◽  
Turnover Rates ◽  
Bayesian Calibration ◽  
Agricultural Use ◽  
Bare Fallow

Abstract. The initialization of soil organic matter (SOM) turnover models has been a challenge for decades. Instead of using laborious and error prone size-density fractionation SOM pool partitioning, we propose the inexpensive, rapid, and non destructive Diffuse reflectance mid infrared Fourier transform spectroscopy (DRIFTS) technique on bulk soil samples to gain information on SOM pool partitioning from the spectra. Specifically, the DRIFTS stability index, defined as the ratio of aliphatic C-H (2930 cm−1) to aromatic C=C (1620 cm−1) stretching vibrations, was used to divide SOM into fast and slow cycling pools in the soil organic module of the DAISY model. Long-term bare fallow plots from Bad Lauchstädt (Chernozem, 25 years) and the Ultuna frame trial in Sweden (Cambisol, 50 years) were combined with bare fallow plots of 7 years duration in the Kraichgau and Swabian Jura region in Southwest Germany (Luvisols). All fields had been in agricultural use for centuries before fallow establishment, so classical theory would suggest an initial steady state of SOM, which was hence used to compare the performance of DAISY initializations against the newly established DRIFTS stability index. The test was done using two different published parameter sets (2.7 × 10−6 d−1, 1.4 × 10−4 d−1, 0.1 compared to 4.3 × 10−5 d−1, 1.4 × 10−4 d−1, 0.3 for the turnover rates of slow pool, fast pool and humification efficiency, respectively). The DRIFTS initialization of SOM pools significantly reduced model errors of poor performing model runs assuming steady state, irrespective of the turnover rates used, but the faster turnover parameter set fit better to all sites except Bad Lauchstädt. This suggests that soils under long-term agricultural use were not necessarily at steady state. A Bayesian calibration was applied in a next step to identify the best-fitting turnover rates for the DRIFTS stability index in DAISY, both for each site individually and for a combination of all sites. The two approaches which significantly reduced parameter uncertainty and equifinality were: (1) the addition of the physico-chemically based DRIFTS stability index, and (2) combining several sites into one Bayesian calibration, as derived turnover rates can be strongly site specific. The combination of all four sites showed that SOM is likely lost at relatively fast turnover rates with the 95 % credibility intervals of the slow SOM pools half life ranging from 278 to 1095 years, with 426 years as a value of highest probability density. The credibility intervals of this study were consistent with several recently published Bayesian calibrations of similar SOM models, all turnover rates were considerably faster than earlier models suggested. It is therefore likely that published turnover rates understimate the potential loss of SOM.

scholarly journals Impacts of long-term plant residue management on soil organic matter quality, Pseudomonas community structure and disease suppressiveness

2019 ◽  
Vol 135 ◽  
pp. 396-406 ◽  
Author(s):  
Bryony E.A. Dignam ◽  
Maureen O'Callaghan ◽  
Leo M. Condron ◽  
Jos M. Raaijmakers ◽  
George A. Kowalchuk ◽  
...  
Keyword(s):  
Organic Matter ◽  
Community Structure ◽  
Soil Organic Matter ◽  
Residue Management ◽  
Plant Residue ◽  
Organic Matter Quality ◽  
Soil Organic Matter Quality

Functional soil organic matter fractions in response to long-term fertilizer management in a double-cropping paddy field of southern China

2021 ◽  
pp. 1-9
Author(s):  
Haiming Tang ◽  
Chao Li ◽  
Lihong Shi ◽  
Li Wen ◽  
Kaikai Cheng ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Paddy Field ◽  
Southern China ◽  
Rice Paddy ◽  
Chemical Fertilizer ◽  
Protection Mechanism ◽  
Rice Paddy Field ◽  
Double Cropping

Abstract Soil organic matter (SOM) and its fractions play an important role in maintaining or improving soil quality and soil fertility. Therefore, the effects of a 34-year long-term fertilizer regime on six functional SOM fractions under a double-cropping rice paddy field of southern China were studied in the current paper. The field experiment included four different fertilizer treatments: chemical fertilizer alone (MF), rice straw residue and chemical fertilizer (RF), 30% organic manure and 70% chemical fertilizer (OM) and without fertilizer input as control (CK). The results showed that coarse unprotected particulate organic matter (cPOM), biochemically, physically–biochemically and chemically protected silt-sized fractions (NH-dSilt, NH-μSilt and H-dSilt) were the main carbon (C) storage fractions under long-term fertilization conditions, accounting for 16.7–26.5, 31.1–35.6, 16.2–17.3 and 7.5–8.2% of the total soil organic carbon (SOC) content in paddy soil, respectively. Compared with control, OM treatment increased the SOC content in the cPOM, fine unprotected POM fraction, pure physically protected fraction and physico-chemically protected fractions by 58.9, 106.7, 117.6 and 28.3%, respectively. The largest proportion of SOC to total SOC in the different fractions was biochemically protected, followed by chemically and unprotected, and physically protected were the smallest. These results suggested that a physical protection mechanism plays an important role in stabilizing C of paddy soil. In summary, the results showed that higher functional SOM fractions and physical protection mechanism play an important role in SOM cycling in terms of C sequestration under the double-cropping rice paddy field.

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