Georg-August Universität Göttingen — Publications

Crop residue quality and quantity have contrasting effects on soil organic matter (SOM) decomposition, but the mechanisms explaining such priming effect (P

C:N stoichiometry of stable and labile organic compounds determine priming patterns

&lt;p&gt;&lt;span&gt;Approximately 50&amp;#8211;70% of C stored in soil is derived from the roots or root-associated microorganisms, reflecting their importance for soil organic matter (SOM) formation. Microorganisms are the major driver for SOM decomposition and their activities are modified by the input of labile organics such as root exudates and low molecular weight organic substances derived from litter decomposition. Such short-term changes in the turnover of SOM caused by moderate organic additions into the soil were defined as priming effects (PE). Priming effects can influence global carbon (C) storage in soil and lead to climate feedbacks by accelerating the decomposition of organic matter (OM). In natural ecosystems, input of nitrate (NO&lt;/span&gt;&lt;span&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;/span&gt;&lt;span&gt;&lt;sup&gt;&amp;#8722;&lt;/sup&gt;&lt;/span&gt;&lt;span&gt;) and ammonium (NH&lt;/span&gt;&lt;span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;/span&gt;&lt;span&gt;&lt;sup&gt;+&lt;/sup&gt;&lt;/span&gt;&lt;span&gt;) into the soil can be derived from nitrogen (N) deposition and biological N fixation. Although availability N can alter the magnitude and direction of priming, it remains unclear whether additions of NO&lt;/span&gt;&lt;span&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;/span&gt;&lt;span&gt;&lt;sup&gt;&amp;#8722;&lt;/sup&gt;&lt;/span&gt;&lt;span&gt; and NH&lt;/span&gt;&lt;span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;/span&gt;&lt;span&gt;&lt;sup&gt;+&lt;/sup&gt;&lt;/span&gt;&lt;span&gt; have distinct effects on the decomposition of OM. Thus, the aims of this study were to investigate the responses of OM 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. Leaf litter, wood litter, organic soil horizon, and mineral soil, with a broad range of C:N ratios were collected along a decay continuum in a typical subtropical forest and incubated for 38 days with &lt;/span&gt;&lt;span&gt;&lt;sup&gt;13&lt;/sup&gt;&lt;/span&gt;&lt;span&gt;C labeled glucose and N (NO&lt;/span&gt;&lt;span&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;/span&gt;&lt;span&gt;&lt;sup&gt;&amp;#8722;&lt;/sup&gt;&lt;/span&gt;&lt;span&gt;) additions. Based on the very broad range of C:N ratios in OM in soil and inputs of labile C and N, we demonstrated the OM decomposition within a decay continuum as well as PE intensities and the thresholds for the switch of PE directions. In contrast to NH&lt;/span&gt;&lt;span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;/span&gt;&lt;span&gt;&lt;sup&gt;+&lt;/sup&gt;&lt;/span&gt;&lt;span&gt;&amp;#160;additions, NO&lt;/span&gt;&lt;span&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;/span&gt;&lt;span&gt;&lt;sup&gt;&amp;#8722;&lt;/sup&gt;&lt;/span&gt;&lt;span&gt; generally accelerated the decomposition of all OM. Priming of plant litter was dependent on the C:N ratios of the labile inputs. However, leaf litter decomposition was more controlled by N addition than wood litter. Glucose addition greatly increased the priming of OM decomposition, demonstrating energy limitation for microorganisms. Distinct priming patterns were observed between NO&lt;/span&gt;&lt;span&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;/span&gt;&lt;span&gt;&lt;sup&gt;&amp;#8722;&lt;/sup&gt;&lt;/span&gt;&lt;span&gt;&amp;#160;and NH&lt;/span&gt;&lt;span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;/span&gt;&lt;span&gt;&lt;sup&gt;+&lt;/sup&gt;&lt;/span&gt;&lt;span&gt; additions, both for the individual OM types and for all four types of OM. The PE induced by labile C and N inputs can increase or reduce C sequestration depending on C:N stoichiometric ratios of labile inputs. Net C losses caused by PE can be observed in organic soil and plant litter with low C and N additions, but all four OM substrates increased C sequestration under high C addition. Minor differences in priming along the continuum were observed where the OM C:N ratio was below 30 when NO&lt;/span&gt;&lt;span&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;/span&gt;&lt;span&gt;&lt;sup&gt;&amp;#8722;&lt;/sup&gt;&lt;/span&gt;&lt;span&gt;&amp;#160;was added and where the labile C:N ratio was less than 55 when NH&lt;/span&gt;&lt;span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;/span&gt;&lt;span&gt;&lt;sup&gt;+&lt;/sup&gt;&lt;/span&gt;&lt;span&gt; was added. Thus, &lt;/span&gt;&lt;span&gt;changes in the composition of deposited N (atmospheric deposition and fertilization) may induce distinct climate feedbacks. Under future climatic conditions by global warming and elevated CO&lt;/span&gt;&lt;span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;/span&gt;&lt;span&gt;, more labile C inputs via root exudates could accelerate litter decomposition. Effects of N however, depend on the N form: NH&lt;/span&gt;&lt;span&gt;&lt;sub&gt;4&lt;/sub&gt;&lt;/span&gt;&lt;span&gt;&lt;sup&gt;+&lt;/sup&gt;&lt;/span&gt;&lt;span&gt;&amp;#160;to NO&lt;/span&gt;&lt;span&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;/span&gt;&lt;span&gt;&lt;sup&gt;&amp;#8722;&lt;/sup&gt;&lt;/span&gt;&lt;span&gt;&amp;#160;due to the energy necessary for microorganisms for NO&lt;/span&gt;&lt;span&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;/span&gt;&lt;span&gt;&lt;sup&gt;-&lt;/sup&gt;&lt;/span&gt;&lt;span&gt; reduction.&lt;/span&gt;&lt;/p&gt;

Min Liu, Na Qiao, Xingliang Xu et al. 2020Article

Publications

Transformation of Low-Molecular Nitrogen-Containing Compounds in Soil

Microbial decomposition of soil organic matter is mediated by quality and quantity of crop residues: mechanisms and thresholds

Nitrogen transformations in soil under plastic film mulching

Stimulation of r- vs. K- selected microorganisms by elevated atmospheric CO2 depends on soil aggregate size

Earthworms for Soil Organic Matter Mineralization and Carbon Sequestration

Activation Energy of Organic Matter Decomposition in Soil and Consequences of Global Warming

Corrigendum to “Habitat heterogeneity drives arbuscular mycorrhizal fungi and shrub communities in karst ecosystems” [CATENA 233 (2023) 107513]

Pore‐scale view of microbial turnover: Combining <scp><sup>14</sup>C</scp> imaging, <scp>μCT</scp> and zymography after adding soluble carbon to soil pores of specific sizes

Plant inter-species effects on rhizosphere priming effect and nitrogen acquisition by plants

Microbial metabolisms determine soil priming effect induced by organic inputs

Root and mycorrhizal strategies for nutrient acquisition in forests under nitrogen deposition: A meta-analysis

Effects of Biochar and Polyacrylamide on Decomposition of Organic Matter and ¹⁴C-labelled Alfalfa Residues in Soil

C:N stoichiometry of stable and labile organic compounds determine priming patterns

Unraveling the molecular and physiological responses of a major industrial crop Nicotiana tabacum exposed to preservative parabens

Carbon and nitrogen mineralization and enzyme activities in soil aggregate-size classes: Effects of biochar, oyster shells, and polymers

Hot experience for cold-adapted microorganisms: Temperature sensitivity of soil enzymes

Mediterranean soils under climate change: a drying-rewetting experiment with 14C-labelled glucose

Analysis and Modeling of soil hydrology under different soil additives in artificial runoff plots

Contribution of roots to soil organic carbon: From growth to decomposition experiment

Effects of polyacrylamide, biopolymer, and biochar on decomposition of soil organic matter and plant residues as determined by 14C and enzyme activities