Article

The Global Stoichiometry of Litter Nitrogen Mineralization

Civil and Environmental Engineering Department, Duke University, Durham, NC 27708, USA.
Science (Impact Factor: 33.61). 09/2008; 321(5889):684-6. DOI: 10.1126/science.1159792
Source: PubMed

ABSTRACT

Plant residue decomposition and the nutrient release to the soil play a major role in global carbon and nutrient cycling.
Although decomposition rates vary strongly with climate, nitrogen immobilization into litter and its release in mineral forms
are mainly controlled by the initial chemical composition of the residues. We used a data set of ∼2800 observations to show
that these global nitrogen-release patterns can be explained by fundamental stoichiometric relationships of decomposer activity.
We show how litter quality controls the transition from nitrogen accumulation into the litter to release and alters decomposers'
respiration patterns. Our results suggest that decomposers lower their carbon-use efficiency to exploit residues with low
initial nitrogen concentration, a strategy used broadly by bacteria and consumers across trophic levels.

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    • "altering soil microbial community due to a greater C use efficiency which accelerates the mineralization of native organic matter (Derrien et al., 2014; Kuzyakov, 2010; Manzoni et al., 2008). Thus, given the short-term nature of our experiment (i.e. 6 years), we could hypothesize that this effect could have played a major role in the turnover of the initial SOC in the GL1 and GL2 treatments. "
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    ABSTRACT: Inserting legumes in low-input innovative cropping systems can represent a good strategy to reduce current N fertilizer dependency while enhancing ecosystem services. However, although the impact of the use of legumes as cover crops has been broadly studied, very little is known about the effects of grain legume-based rotations on soil organic carbon (SOC) and nitrogen (SON). A cropping system experiment with three 3-year rotations with different levels of inclusion of grain legumes: GL0, GL1 and GL2 (none, one, and two grain legumes, respectively), with (CC) or without (BF, bare fallow) cover crops was established in SW France (Auzeville) under temperate climate. Durum wheat was present in all the rotations to act as an indicator of their performance. Soil organic C and SON were quantified before the beginning of the experiment and after 3 and 6 years (i.e., after one and two complete 3-yr rotations). Aboveground C and N inputs to the soil, and C and N harvest indexes and grain yield of the cash crops were also measured. Inserting grain legumes in the rotations significantly affected the amount of C and N inputs and consequently SOC and SON. After two cycles of the 3-yr rotation, the GL1 and GL2 treatments showed a greater decrease in SOC and SON when compared to GL0. However, the inclusion of cover crops in the rotations led to mitigate this loss. Durum wheat produced significantly greater grain yields in GL1 when compared to GL0, while GL2 presented intermediate values. In turn, the incorporation of cover crops did not reduce C and N harvest indexes or the grain yield of the different cash crops. We concluded that, in such conventionally-tilled grain legume-based rotations, the use of cover crops was efficient to mitigate SOC and SON losses and then increase N use efficiency at the cropping system level without reducing productivity.
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    • "We integrate Davidson et al.'s [2012] conceptual framework of quantifying concentration of soluble C substrates that are directly accessible for microbial assimilation, thus building a direct linkage between environmental factors with microbial state transitions. Substrate quality is also reflected in the model through a generic index of soil C:N ratio [Manzoni et al., 2008], and the assimilation of substrate by microorganisms is assumed to be regulated by the C:N ratio of microbial biomass and that of the soil. We apply the model to simulate the top 30 cm of the soil due to data availability for site validation. "
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    Full-text · Article · Dec 2015 · Journal of Geophysical Research: Biogeosciences
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    • "Climate, litter quality and soil organisms have been identified as the key variables controlling C turnover and nutrient mineralization of surface litter in terrestrial ecosystems (Meentemeyer 1978; Swift, Heal & Anderson 1979; Hobbie 1992; Co^ uteaux, Bottner & Berg 1995). More recently, the complex interactions among these variables have demonstrated several global scale patterns: litter characteristics determined by plant traits including leaf mass per area (LMA), recalcitrant C (lignin) and initial litter nutrient content appear to cross ecosystems as general controls on mass loss (Parton et al. 2007; Cornwell et al. 2008; Manzoni et al. 2008); changes in allocation and growth strategies within and across species can have large impacts on decomposition (Vivanco & Austin 2006; Orwin et al. 2010; Freschet et al. 2013; Hobbie 2015); and litter-soil biota interactions and their interaction with climate are increasingly recognized as an important factor in determining the first stages of C and nitrogen turnover (Garc ıa-Palacios et al. 2013; van der Putten et al. 2013; Austin et al. 2014; Bradford et al. 2014). As such, there is much current interest in understanding the importance of these interactive controls on litter decomposition in the context of ecosystems altered by human impact and predicted climate change. "
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