Glyphosate-based herbicides alter soil carbon and phosphorus dynamics and microbial activity

Abstract. The large magnitudes of soil carbon stocks provide potentially large feedbacks to climate changes, highlighting the need to better understand and represent the environmental sensitivity of soil carbon decomposition. Most soil carbon decomposition models rely on empirical relationships omitting key biogeochemical mechanisms and their response to climate change is highly uncertain. In this study, we developed a multi-layer mechanistically based soil decomposition model framework for boreal forest ecosystems. A global sensitivity analysis was conducted to identify dominating biogeochemical processes and to highlight structural limitations. Our results indicate that substrate availability (limited by soil water diffusion and substrate quality) is likely to be a major constraint on soil decomposition in the fibrous horizon (40–60% of SOC pool size variation), while energy limited microbial activity in the amorphous horizon exerts a predominant control on soil decomposition (>70% of SOC pool size variation). Elevated temperature alleviated the energy constraint of microbial activity most notably in amorphous soils; whereas moisture only exhibited a marginal effect on dissolved substrate supply and microbial activity. Our study highlights the different decomposition properties and underlying mechanisms of soil dynamics between fibrous and amorphous soil horizons. Soil decomposition models should consider explicitly representing different boreal soil horizons and soil-microbial interactions to better characterize biogeochemical processes in boreal ecosystems. A more comprehensive representation of critical biogeochemical mechanisms of soil moisture effects may be required to improve the performance of the soil model we analyzed in this study.

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CO2-C losses and carbon quality of selected Maritime Antarctic soils

Antarctic Science ◽

10.1017/s0954102012000648 ◽

2012 ◽

Vol 25 (1) ◽

pp. 11-18 ◽

Cited By ~ 9

Author(s):

Juliana Vanir De Souza Carvalho ◽

Eduardo De Sá Mendonça ◽

Newton La Scala ◽

César Reis ◽

Efrain Lázaro Reis ◽

...

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Soil Temperature ◽

Soil Carbon ◽

Humic Substances ◽

Microbial Activity ◽

Chemical Characteristics ◽

Maritime Antarctic ◽

Antarctic Soils ◽

Humification Degree

AbstractPolar Regions are the most important soil carbon reservoirs on Earth. Monitoring soil carbon storage in a changing global climate context may indicate possible effects of climate change on terrestrial environments. In this regard, we need to understand the dynamics of soil organic matter in relation to its chemical characteristics. We evaluated the influence of chemical characteristics of humic substances on the process of soil organic matter mineralization in selected Maritime Antarctic soils. A laboratory assay was carried out with soils from five locations from King George Island. We determined the contents of total organic carbon, oxidizable carbon fractions of soil organic matter, and humic substances. Two in situ field experiments were carried out during two summers, in order to evaluate the CO2-C emissions in relation to soil temperature variations. The overall low amounts of soil organic matter in Maritime Antarctic soils have a low humification degree and reduced microbial activity. CO2-C emissions showed significant exponential relationship with temperature, suggesting a sharp increase in CO2-C emissions with a warming scenario, and Q10 values (the percentage increase in emission for a 10°C increase in soil temperature) were higher than values reported from elsewhere. The sensitivity of the CO2-C emission in relation to temperature was significantly correlated with the humification degree of soil organic matter and microbial activity for Antarctic soils.

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Soil carbon, microbial activity and nitrogen availability in agroforestry systems on moderately alkaline soils in northern India

Applied Soil Ecology ◽

10.1016/s0929-1393(00)00079-2 ◽

2000 ◽

Vol 15 (3) ◽

pp. 283-294 ◽

Cited By ~ 81

Author(s):

B. Kaur ◽

S.R. Gupta ◽

G. Singh

Keyword(s):

Soil Carbon ◽

Microbial Activity ◽

Nitrogen Availability ◽

Agroforestry Systems ◽

Alkaline Soils ◽

Northern India

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The implications of microbial and substrate limitation for the fates of carbon in different organic soil horizon types of boreal forest ecosystems: a mechanistically based model analysis

Biogeosciences ◽

10.5194/bg-11-4477-2014 ◽

2014 ◽

Vol 11 (16) ◽

pp. 4477-4491 ◽

Cited By ~ 17

Author(s):

Y. He ◽

Q. Zhuang ◽

J. W. Harden ◽

A. D. McGuire ◽

Z. Fan ◽

...

Keyword(s):

Boreal Forest ◽

Soil Carbon ◽

Microbial Activity ◽

Forest Ecosystems ◽

Size Variation ◽

Pool Size ◽

Biogeochemical Processes ◽

Soil Horizons ◽

Carbon Decomposition ◽

Decomposition Models

Abstract. The large amount of soil carbon in boreal forest ecosystems has the potential to influence the climate system if released in large quantities in response to warming. Thus, there is a need to better understand and represent the environmental sensitivity of soil carbon decomposition. Most soil carbon decomposition models rely on empirical relationships omitting key biogeochemical mechanisms and their response to climate change is highly uncertain. In this study, we developed a multi-layer microbial explicit soil decomposition model framework for boreal forest ecosystems. A thorough sensitivity analysis was conducted to identify dominating biogeochemical processes and to highlight structural limitations. Our results indicate that substrate availability (limited by soil water diffusion and substrate quality) is likely to be a major constraint on soil decomposition in the fibrous horizon (40–60% of soil organic carbon (SOC) pool size variation), while energy limited microbial activity in the amorphous horizon exerts a predominant control on soil decomposition (>70% of SOC pool size variation). Elevated temperature alleviated the energy constraint of microbial activity most notably in amorphous soils, whereas moisture only exhibited a marginal effect on dissolved substrate supply and microbial activity. Our study highlights the different decomposition properties and underlying mechanisms of soil dynamics between fibrous and amorphous soil horizons. Soil decomposition models should consider explicitly representing different boreal soil horizons and soil–microbial interactions to better characterize biogeochemical processes in boreal forest ecosystems. A more comprehensive representation of critical biogeochemical mechanisms of soil moisture effects may be required to improve the performance of the soil model we analyzed in this study.

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