scholarly journals Soil Microbial Responses to 28 Years of Nutrient Fertilization in a Subarctic Heath

Ecosystems ◽  
2019 ◽  
Vol 23 (5) ◽  
pp. 1107-1119 ◽  
Author(s):  
Lettice C. Hicks ◽  
Kathrin Rousk ◽  
Riikka Rinnan ◽  
Johannes Rousk
Keyword(s):  
Community Structure ◽  
Soil Microorganisms ◽  
N Availability ◽  
Soil C ◽  
Soil Microbial ◽  
C And N Mineralization ◽  
Microbial Responses ◽  
Soil C And N ◽  
C And N

AbstractArctic and subarctic soils are typically characterized by low nitrogen (N) availability, suggesting N-limitation of plants and soil microorganisms. Climate warming will stimulate the decomposition of organic matter, resulting in an increase in soil nutrient availability. However, it remains unclear how soil microorganisms in N-limited soils will respond, as the direct effect of inorganic N addition is often shown to inhibit microbial activity, while elevated N availability may have a positive effect on microorganisms indirectly, due to a stimulation of plant productivity. Here we used soils from a long-term fertilization experiment in the Subarctic (28 years at the time of sampling) to investigate the net effects of chronic N-fertilization (100 kg N ha−1 y−1, added together with 26 kg P and 90 kg K ha−1 y−1, as expected secondary limiting nutrients for plants) on microbial growth, soil C and N mineralization, microbial biomass, and community structure. Despite high levels of long-term fertilization, which significantly increased primary production, we observed relatively minor effects on soil microbial activity. Bacterial growth exhibited the most pronounced response to long-term fertilization, with higher rates of growth in fertilized soils, whereas fungal growth remained unaffected. Rates of basal soil C and N mineralization were only marginally higher in fertilized soils, whereas fertilization had no significant effect on microbial biomass or microbial community structure. Overall, these findings suggest that microbial responses to long-term fertilization in these subarctic tundra soils were driven by an increased flow of labile plant-derived C due to stimulated plant productivity, rather than by direct fertilization effects on the microbial community or changes in soil physiochemistry.

scholarly journals Soil carbon and nitrogen and barley yield responses to repeated additions of compost and slurry

2016 ◽  
Vol 155 (1) ◽  
pp. 141-155
Author(s):  
D. W. HOPKINS ◽  
R. E. WHEATLEY ◽  
C. M. COAKLEY ◽  
T. J. DANIELL ◽  
S. M. MITCHELL ◽  
...  
Keyword(s):  
Community Structure ◽  
Microbial Biomass ◽  
Bacterial Community Structure ◽  
Soil Microbial Biomass ◽  
Organic Amendments ◽  
Soil C ◽  
Soil Microbial ◽  
Respiration Rates ◽  
Soil C And N ◽  
C And N

SUMMARYThe yields of spring barley during a medium-term (7 years) compost and slurry addition experiment and the soil carbon (C) and nitrogen (N) contents, bacterial community structure, soil microbial biomass and soil respiration rates have been determined to assess the effects of repeated, and in some cases very large, organic amendments on soil and crop parameters. For compost, total additions were equivalent to up to 119 t C/ha and 1·7 t N/ha and for slurry they were 25 t C/ha and 0·35 t N/ha over 7 years, which represented very large additions compared to control soil C and N contents (69 t C/ha and 0·3 t N/ha in the 0–30 cm soil depth). There was an initial positive response to compost and slurry addition on barley yield, but over the experiment the yield differential between the amounts of compost addition declined, indicating that repeated addition of compost at a lower rate over several years had the same cumulative effect as a large single compost application. By the end of the experiment it was clear that the addition of compost and slurry increased soil C and N contents, especially towards the top of the soil profile, as well as soil respiration rates. However, the increases in soil C and N contents were not proportional to the amount of C and N added, suggesting either that: (i) a portion of the added C and N was more vulnerable to loss; (ii) that its addition rendered another C or N pool in the soil more susceptible to loss; or (iii) that the C inputs from additional crop productivity did not increase in line with the organic amendments. Soil microbial biomass was depressed at the highest rate of organic amendment, and whilst this may have been due to genuine toxic or inhibitory effects of large amounts of compost, it could also be due to the inaccuracy of the substrate-induced respiration approach used for determining soil biomass when there is a large supply of organic matter. At the highest compost addition, the bacterial community structure was significantly altered, suggesting that the amendments significantly altered soil community dynamics.

scholarly journals Linking Cover Crop Residue Quality and Tillage System to CO2-C Emission, Soil C and N Stocks and Crop Yield Based on a Long-Term Experiment

Agronomy ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1848
Author(s):  
Otávio A. Leal ◽  
Telmo J. C. Amado ◽  
Jackson E. Fiorin ◽  
Cristiano Keller ◽  
Geovane B. Reimche ◽  
...  
Keyword(s):  
Crop Yield ◽  
Cover Crops ◽  
No Tillage ◽  
Yield Data ◽  
Soil C ◽  
Term Experiment ◽  
Long Term Experiment ◽  
Soil C And N ◽  
C And N

Cover crops (CC), particularly legumes, are key to promote soil carbon (C) sequestration in no-tillage. Nevertheless, the mechanisms regulating this process need further elucidation within a broad comprehensive framework. Therefore, we investigated effects of CC quality: black oat (Avena strigosa Schreb) (oat), common vetch (Vicia sativa L.) (vetch), and oat + vetch on carbon dioxide-C (CO2-C) emission (124 days) under conventional- (CT), minimum- (MT) and no-tillage (NT) plots from a long-term experiment in Southern Brazil. Half-life time (t1/2) of CC residues and the apparent C balance (ACB) were obtained for CT and NT. We linked our data to long-term (22 years) soil C and nitrogen (N) stocks and crop yield data of our experimental field. Compared to CT, NT increased t1/2 of oat, oat + vetch and vetch by 3.9-, 3.1- and 3-fold, respectively; reduced CO2-C emissions in oat, oat + vetch and vetch by 500, 600 and 642 kg ha−1, respectively; and increased the ACB (influx) in oat + vetch (195%) and vetch (207%). For vetch, CO2-C emission in MT was 77% greater than NT. Legume CC should be preferentially combined with NT to reduce CO2-C emissions and avoid a flush of N into the soil. The legume based-NT system showed the greatest soil C and N sequestration rates, which were significantly and positively related to soybean (Glycine max (L.) Merrill) and maize (Zea mays L.) yield. Soil C (0–90 cm depth) and N (0–100 cm depth) sequestration increments of 1 kg ha−1 corresponded to soybean yield increments of 1.2 and 7.4 kg ha−1, respectively.

Effect of forest soil warming on the rate and temperature sensitivity of microbial C and N processes in a temperate mountain forest

2020 ◽  
Author(s):  
Carolina Urbina Malo ◽  
Ye Tian ◽  
Chupei Shi ◽  
Shasha Zhang ◽  
Marilena Heitger ◽  
...  
Keyword(s):  
Forest Soil ◽  
Temperature Sensitivity ◽  
Enzyme Activities ◽  
Thermal Acclimation ◽  
Soil Warming ◽  
Soil C ◽  
Soil Microbial ◽  
C And N ◽  
N Acquisition

<p>Despite the intensified efforts to understand the impacts of climate change on forest soil C dynamics, few studies have addressed the long term effects of warming on microbially mediated soil C and nutrient processes. In the few long-term soil warming experiments the initial stimulation of soil C cycling diminished with time, due to thermal acclimation of the microbial community or due to depletion of labile soil C as the major substrate for heterotrophic soil microbes. Thermal acclimation can arise as a consequence of prolonged warming and is defined as the direct organism response to elevated temperature across annual to decadal time-scales which manifest as a physiological change of the soil microbial community. This mechanism is clearly different from apparent thermal acclimation, where the attenuated response of soil microbial processes to warming is due to the exhaustion of the labile soil C pool.</p><p>The Achenkirch experiment, situated in the Northern Limestone Alps, Austria (47°34’ 50’’ N; 11°38’ 21’’ E; 910 m a.s.l.) is a long term (>15 yrs) soil warming experiment that has provided key insights into the effects of global warming on the forest soil C cycle. At the Achenkirch site, we have observed a sustained positive response of heterotrophic soil respiration and of soil CO<sub>2</sub> efflux to warming after nine years (2013), making it an appropriate setting for testing hypotheses about continued or decreasing warming effects at decadal scales. We collected soil from six warmed and six control plots in October 2019, from 0-10 cm and 10-20 cm depth, and incubated them at three different temperatures: ambient, +4, and +10 °C. We measured potential soil enzyme activities with fluorimetric assays, gross rates of protein depolymerization, N mineralization, and nitrification with <sup>15</sup>N isotope pool dilution approaches, and microbial growth, respiration, and C use efficiency (CUE) based on the <sup>18</sup>O incorporation in DNA and gas analysis.  Our preliminary results show that potential enzyme activities of aminopeptidase, N-acetylglucosaminidase, b-glucosidase, and acid phosphatase were stimulated by decadal soil warming by 1.7- to 3.5-fold, measured at the same i.e. ambient temperature. In contrast, the temperature sensitivity (Q10) remained unaltered between warmed and control soils for all enzyme activities (Q10=1.63-2.28), except for aminopeptidase where we observed a decrease in Q10 by 25% in warmed topsoils (0-10 cm). Aminopeptidase also had the highest temperature-sensitivity (Q10=2.39), causing a decrease of the enzymatic C: N acquisition ratio with warming. These results indicate an increasing investment in microbial N acquisition with warming. We will follow these trends based on results on gross rates of soil C and N processes, allowing to delineate decadal soil warming effects on soil microbial biogeochemistry and to understand their effect on the cross-talk between organic C and N cycling in calcareous forest soils.</p>

The magnitude of temperature increase matters: how will soil organic mineralization respond to future climate warming?

2020 ◽  
Author(s):  
Jie Zhou ◽  
Yuan Wen ◽  
Lingling Shi ◽  
Michaela Dippold ◽  
Yakov Kuzyakov ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Climate Warming ◽  
Temperature Increase ◽  
Microbial Growth ◽  
N Cycling ◽  
Soil C ◽  
Soil Microbial ◽  
Soil C And N ◽  
C And N ◽  
C And N Cycling

<p>The Paris climate agreement is pursuing efforts to limit the increase in global temperature to below 2 °C above pre-industrial level. The overall consequence of relatively slight warming (~2 °C), on soil C and N stocks will be dependent on microorganisms decomposing organic matter through release of extracellular enzymes. Therefore, the capacity of soil microbial community to buffer climate warming in long-term and the self-regulatory mechanisms mediating soil C and N cycling through enzyme activity and microbial growth require a detailed comparative study. Here, microbial growth and the dynamics of enzyme activity (involved in C and N cycling) in response to 8 years warming (ambient, +1.6 °C, +3.2 °C) were investigated to identify shifts in soil and microbial functioning. A slight temperature increase (+1.6 °C) only altered microbial properties, but had no effect on either hydrolytic enzyme activity or basic soil properties. Stronger warming (+3.2 °C) increased the specific growth rate (μ<sub>m</sub>) of the microbial community, indicating an alteration in their ecological strategy, i.e. a shift towards fast-growing microorganisms and accelerated microbial turnover. Warming strongly changed microbial physiological state, as indicated by a 1.4-fold increase in the fraction of growing microorganisms (GMB) and 2 times decrease in lag-time with warming. This reduced total microbial biomass but increased specific enzyme activity to be ready to decompose increased rhizodeposition, as supported by the higher potential activitiy (V<sub>max</sub>) and lower affinity to substrates (higher K<sub>m</sub>) of enzymes hydrolyzing cellobiose and proteins cleavage in warmed soil. In other words, stronger warming magnitude (+3.2 °C) changed microbial communities, and was sufficient to benefit fast-growing microbial populations with enzyme functions that specific to degrade labile SOM. Combining with 48 literature observations, we confirmed that the slight magnitude of temperature increase (< 2 °C) only altered microbial properties, but further temperature increases (2-4 °C) was sufficient to change almost all soil, microbial, and enzyme properties and related processes. As a consequence, the revealed microbial regulatory mechanism of stability of soil C storage is strongly depended on the magnitude of future climate warming.</p>

scholarly journals Trade-offs between the short- and long-term effects of residue quality on soil C and N dynamics

2010 ◽  
Vol 338 (1-2) ◽  
pp. 159-169 ◽  
Author(s):  
Roberta Gentile ◽  
Bernard Vanlauwe ◽  
Pauline Chivenge ◽  
Johan Six
Keyword(s):  
Residue Quality ◽  
Long Term Effects ◽  
N Dynamics ◽  
Soil C ◽  
Trade Offs ◽  
Short And Long Term ◽  
Soil C And N ◽  
C And N ◽  
C And N Dynamics

Soil C and N availability determine the priming effect: microbial N mining and stoichiometric decomposition theories

2014 ◽  
Vol 20 (7) ◽  
pp. 2356-2367 ◽  
Author(s):  
Ruirui Chen ◽  
Mehmet Senbayram ◽  
Sergey Blagodatsky ◽  
Olga Myachina ◽  
Klaus Dittert ◽  
...  
Keyword(s):  
Priming Effect ◽  
N Availability ◽  
Soil C ◽  
Soil C And N ◽  
C And N ◽  
Microbial N
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