Enzyme properties down the soil profile - A matter of substrate quality in rhizosphere and detritusphere

Loeppmann, Sebastian; Blagodatskaya, Еvgenia; Pausch, Johanna; Kuzyakov, Yakov

doi:10.1016/j.soilbio.2016.08.023

Cited by 72 publications

(64 citation statements)

References 68 publications

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“…When the understory vegetation is removed, the plant diversity decreases, and the soil C content also decreases. Previously, researchers found that soil N contents increased when the amount of N taken up by plants decreased during tree girdling experiments (Kaiser et al, 2010) and in soils without live roots (Loeppmann et al, 2016a). However, we found that the soil N increased when the understory vegetation remained intact, which suggests that the amount of available N released from plant roots and SOM degradation exceeded the amount taken up by plants.…”

Section: Discussioncontrasting

confidence: 71%

“…Because it is difficult to know whether changes in the enzymatic activities reflect changes in the soil microbial biomass or differences in the actual activities (Trasar-Cepeda et al, 2008), we need to study the specific enzyme activities, i.e., the activity normalized to the total PLFA contents (Zhang et al, 2015(Zhang et al, , 2017. The enzyme ratio is used to examine the relative allocation of energy versus nutrient acquisition, since it intersects the metabolic theory of microbial ecology and the theory of ecological stoichiometry (Stone et al, 2014;Loeppmann et al, 2016a;Xu et al, 2017). By studying how the enzyme activities and ratios change when the understory vegetation is removed, we hope to improve our understanding of how the storage of C in soil is influenced by the understory vegetation, and how microbial nutrient acquisition is affected by microbial biomass and soil nutrients.…”

Section: Introductionmentioning

confidence: 99%

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Understory vegetation plays the key role in sustaining soil microbial biomass and extracellular enzyme activities

Yang

Zhang

et al. 2018

Biogeosciences

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Abstract. While we know that understory vegetation affects the soil microbial biomass and extracellular enzyme activities in subtropical Chinese fir (Cunninghamia lanceolata) forests, we are less certain about the degree of its influence. We determined the degree to which the soil abiotic and biotic properties, such as PLFAs and extracellular enzyme activities, were controlled by understory vegetation. We established a paired treatment in a subtropical Chinese fir plantation, which comprised one plot from which the understory vegetation and litter were removed (None) and another from which the litter was removed but the understory vegetation was left intact (Understory). We evaluated how the understory vegetation influenced the soil abiotic properties, the bacterial, fungal, and actinobacterial PLFAs, and the activities of five hydrolases and two oxidative enzymes. The dissolved organic carbon (DOC), particulate organic carbon, soil organic carbon, ammonia nitrogen (NH4+–N), and total nitrogen contents and soil moisture were 18 %, 25 %, 12 %, 34 %, 8 %, and 4 % lower in the None treatments than in the Understory treatments, respectively (P<0.05). Soil bacterial, fungal, and total PLFAs, and the potential activities of β-1,4-glucosidase (βG), β-1,4-N-acetylglucosaminidase, phenol oxidase, and peroxidase, were as much as 24 % lower in None treatments than in Understory treatments (P<0.05). The specific activities of C-acquiring enzymes were as much as 41 % higher (P<0.05), and the ratio of C- to N-acquiring enzymes was also higher in the None treatments than in the Understory treatments. This suggests that in the absence of understory vegetation microbes invested more in C acquisition than N acquisition because the carbon (C) inputs were less labile. The negative relationship between DOC and AP shows that DOC is consumed when P-acquiring enzymes are produced. The positive correlation between NH4+–N and βG suggested the increased availability of N promoted the decomposition of C. More extracellular enzymes that degrade soil organic matter are produced when there is understory vegetation, which leads to losses of soil C. On the other hand, the soil C sink is maintained by increased inputs of C. We can therefore conclude that understory vegetation contributes to C sequestration in Chinese fir forests and suggest that understory should be maintained to sustain soil quality in subtropical Chinese fir plantations.

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Section: Discussioncontrasting

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Understory vegetation plays the key role in sustaining soil microbial biomass and extracellular enzyme activities

Yang

Zhang

et al. 2018

Biogeosciences

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“…Cattle manure increased the pH in October, in accordance with previous studies (Li et al 2018), which may limit the growth of some microorganisms. The impact of fallow conditions on carbon was nonsignificant, in accordance with a previous study (Loeppmann et al 2016). The effects of spontaneous grass with manure on TN were significant beginning in August.…”

Section: Discussionsupporting

confidence: 91%

“…The nitrate nitrogen content under Sesbania fallowing was greater than that under natural fallowing because of the nitrogen mineralization of Sesbania (Mekonnen et al 1997). Moreover, natural fallowing and fallowing with maize litter (one year) resulted in more extractable nitrogen in the examined soil layers (0-40 cm) than planted maize because of the high nitrogen utilization via enzymes in fallow farmlands (Loeppmann et al 2016). Soil carbon seems to be more stable than soil nitrogen.…”

Section: Introductionmentioning

confidence: 92%

Peer Review #2 of "Improvement of subsoil physicochemical and microbial properties by short-term fallow practices (v0.2)"

2019

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Fallow management can improve the soil nutrients in the topsoil and upper subsoil. However, little is known about the effects of short-term (one year) fallowing with different treatments, such as vegetation and fertilization, on subsoil (20-40 cm) properties. We conducted field trials to explore the changes in subsoil properties in response to such treatments in the Yellow River Delta region in China. Different vegetation and fertilization treatments were applied, and we measured the carbon and nitrogen contents, microbial biomass and microbial community structure in the subsoil. Fallowing without manure resulted in the storage of more total nitrogen (16.38%) than fallowing with manure, and meadow vegetation improved the ammonium nitrogen content (45.71%) relative to spontaneous vegetation. Spontaneous vegetation with manure improved the microbial biomass nitrogen (P < 0.05). Although the impact of short-term fallowing on microbial community structure was low, an effect of management was observed for some genera. Blastopirellula, Lysobacter, and Acidobacteria Gp6 showed significant differences among fallow treatments by the end of the year (P < 0.05). Blastopirellula abundance was related to the microbial biomass nitrogen and nitrogen mineralization rate in the subsoil. Manure retained a high abundance of Lysobacter, which may strengthen soil-borne disease resistance. The response of Acidobacteria Gp6 showed that meadow vegetation without manure may not benefit future crops. Although the treatments did not significantly improve microbial community structure in the one-year period, annual fallowing improved certain subsoil properties and increased the number of functional genera, which may enhance crop productivity in the future.

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“…Resulting increases in soil N cycling can also be tied to greater N uptake by trees (Drake et al 2011). Along with the positive rhizosphere effect on N-acquiring enzyme activities (Koranda et al 2011;Ciadamidaro et al 2014;Loeppmann et al 2016), plants can also stimulate the microbial production of oxidative enzymes, like laccase, peroxidase and phenol oxidase (Carney et al 2007;Phillips et al 2011;Partavian et al, 2015).…”

Section: Indirect Destabilization Pathwaysmentioning

confidence: 99%

Minerals in the rhizosphere: overlooked mediators of soil nitrogen availability to plants and microbes

et al. 2018

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Despite decades of research progress, ecologists are still debating which pools and fluxes provide nitrogen (N) to plants and soil microbes across different ecosystems. Depolymerization of soil organic N is recognized as the rate-limiting step in the production of bioavailable N, and it is generally assumed that detrital N is the main source. However, in many mineral soils, detrital polymers constitute a minor fraction of total soil organic N. The majority of organic N is associated with clay-sized particles where physicochemical interactions may limit the accessibility of N-containing compounds. Although mineralassociated organic matter (MAOM) has historically been considered a critical, but relatively passive, reservoir of soil N, a growing body of research now points to the dynamic nature of mineral-organic associations and their potential for destabilization. Here we synthesize evidence from biogeoscience and soil ecology to demonstrate how MAOM is an important, yet overlooked, mediator of bioavailable N, especially in the rhizosphere. We highlight several biochemical strategies that enable plants and microbes /doi.org/10.1007/s10533-018-0459-5 to disrupt mineral-organic interactions and access MAOM. In particular, root-deposited low-molecularweight exudates may enhance the mobilization and solubilization of MAOM, increasing its bioavailability. However, the competitive balance between the possible fates of N monomers-bound to mineral surfaces versus dissolved and available for assimilation-will depend on the specific interaction between mineral properties, soil solution, mineral-bound organic matter, and microbes. Building off our emerging understanding of MAOM as a source of bioavailable N, we propose a revision of the Schimel and Bennett (Ecology 85:591-602, 2004) model (which emphasizes N depolymerization), by incorporating MAOM as a potential proximal mediator of bioavailable N.123 Biogeochemistry (2018) 139:103-122 https:/

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Enzyme properties down the soil profile - A matter of substrate quality in rhizosphere and detritusphere

Cited by 72 publications

References 68 publications

Understory vegetation plays the key role in sustaining soil microbial biomass and extracellular enzyme activities

Understory vegetation plays the key role in sustaining soil microbial biomass and extracellular enzyme activities

Peer Review #2 of "Improvement of subsoil physicochemical and microbial properties by short-term fallow practices (v0.2)"

Minerals in the rhizosphere: overlooked mediators of soil nitrogen availability to plants and microbes

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