Journal ArticleDOI
The contentious nature of soil organic matter
Johannes Lehmann,Markus Kleber +1 more
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TLDR
It is argued that the available evidence does not support the formation of large-molecular-size and persistent ‘humic substances’ in soils, and instead soil organic matter is a continuum of progressively decomposing organic compounds.Abstract:
Instead of containing stable and chemically unique ‘humic substances’, as has been widely accepted, soil organic matter is a mixture of progressively decomposing organic compounds; this has broad implications for soil science and its applications. The exchange of nutrients, energy and carbon between soil organic matter, the soil environment, aquatic systems and the atmosphere is important for agricultural productivity, water quality and climate. Long-standing theory suggests that soil organic matter is composed of inherently stable and chemically unique compounds. Here we argue that the available evidence does not support the formation of large-molecular-size and persistent ‘humic substances’ in soils. Instead, soil organic matter is a continuum of progressively decomposing organic compounds. We discuss implications of this view of the nature of soil organic matter for aquatic health, soil carbon–climate interactions and land management. Soil organic matter contains a large portion of the world's carbon and plays an important role in maintaining productive soils and water quality. Nevertheless, a consensus on the nature of soil organic matter is lacking. Johannes Lehmann and Markus Kleber argue that soil organic matter should no longer be seen as large and persistent, chemically unique substances, but as a continuum of progressively decomposing organic compounds.read more
Citations
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Journal ArticleDOI
Evidence for the Existence of Humic Acids in Peat Soils Based on Solid-State 13C NMR
TL;DR: In this article, the authenticity of humic substances is demonstrated by recombining the various humic fractions, and comparing the NMR spectrum of the recombined peat with the original untreated peat sample.
Journal ArticleDOI
C:N stoichiometry of stable and labile organic compounds determine priming patterns
TL;DR: In this article, the responses of organic matter decomposition along a decay continuum (i.e., decreasing decomposition degree) to labile C and N inputs and determine the PE induced by the two N forms were investigated.
Journal ArticleDOI
Silicon accumulation controls carbon cycle in wetlands through modifying nutrients stoichiometry and lignin synthesis of Phragmites australis
Shaopan Xia,Zhaoliang Song,Lukas Van Zwieten,Laodong Guo,Changxun Yu,Iain P. Hartley,Hailong Wang +6 more
TL;DR: Wang et al. as discussed by the authors investigated Si distribution, nutrient stoichiometry and lignin abundance in Phragmites australis from a wetland system in China to better understand the biogeochemical cycling and C storage.
Journal ArticleDOI
Carbon contents and fine root production in tropical silvopastoral systems
Danilo Enrique Morales Ruiz,Deb Raj Aryal,René Pinto Ruiz,Francisco Guevara Hernández,Fernando Casanova Lugo,Guadalupe Cleva Villanueva López +5 more
Book ChapterDOI
Delineating the Convergence of Biogeochemical Factors Responsible for Arsenic Release to Groundwater in South and Southeast Asia
TL;DR: In this article, the authors defined the parameters controlling the locations of active microbially driven As release to groundwater, including suboxic/anoxic conditions, microbial communities capable of mediating As(V)/Fe(III) reduction, the reactivity of As-bearing Fe oxides, and the sources and reactivities of organic carbon (C).
References
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Climate change 2007: the physical science basis
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TL;DR: The first volume of the IPCC's Fourth Assessment Report as mentioned in this paper was published in 2007 and covers several topics including the extensive range of observations now available for the atmosphere and surface, changes in sea level, assesses the paleoclimatic perspective, climate change causes both natural and anthropogenic, and climate models for projections of global climate.
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TL;DR: In this article, the carbon sink capacity of the world’s agricultural and degraded soils is 50 to 66% of the historic carbon loss of 42 to 78 gigatons of carbon.
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HUmus Chemistry Genesis, Composition, Reactions
TL;DR: In this paper, the authors present an analysis of organic matter in soil using NMR Spectroscopy and analytical pyrolysis, showing that organic matter is composed of nitrogen and ammonium.