How do microorganisms from permafrost soils respond to short-term warming?

Arctic ecosystems outpace the global rate of temperature increases and are exceptionally susceptible to global warming. Concerns are raising that CO2 and CH4 released from thawing permafrost upon warming may induce a positive feedback to climate change. This is based on the assumption, that microbial activity increases with warming and does not acclimate over time. However, we lack a mechanistic understanding of carbon and nutrient fluxes including their spatial control in the very heterogeneous Arctic landscape. The objective of this study therefore was to elucidate the microbial controls over soil organic matter decomposition in different horizons of the active layer and upper permafrost. We investigated different landscape units (high-centre polygons, low-centre polygons and flat polygon tundra) in two small catchments that differ in glacial history, at the Yukon coast, Northwestern Canada.In total, 81 soil samples were subjected to short-term (eight weeks) incubation experiments at controlled temperature (4 &#176;C and 14 &#176;C) and moisture conditions. Heterotrophic respiration was assessed weekly, whereas physiological parameters of soil microbes and their temperature response (Q10) were determined at the end of the incubation period. Microbial growth was estimated by measuring the incorporation of 18O from labelled water into DNA and used to calculate microbial carbon use efficiencies (CUE). Microbial biomass was determined via chloroform fumigation extraction. Potential activities of extracellular enzymes involved in C, N, P and S cycling were measured using microplate fluorimetric assays.Cumulative heterotrophic respiration of investigated soil layers followed the pattern organic layers > upper frozen permafrost > cryoturbated material > mineral layers in both catchments. Microbial respiration responded strongly in all soils to warming in all soils, but the observed response was highest for organic layers and cryoturbated material at the beginning and end of the experiment. Average Q10 values at the beginning of the experiment varied between 1.7 to 4.3 with differences between horizons but converged towards Q10 values between 2.0min to 2.9max after eight weeks of incubation. Even though microbial biomass C did not change with warming, microbial mass specific growth was enhanced in organic, cryoturbated and permafrost soils. Overall, warming resulted in a 65% reduced CUE in organic horizons.Our results show no indication for physiological acclimatization of permafrost soil microbes when subjected to 8-weeks of experimental warming. Given that the duration of the season in which most horizons are unfrozen is rarely longer than 2 months, our results do not support an acclimation of microbial activity under natural conditions. Instead, our data supports the current view of a high potential for prolonged carbon losses from tundra soils with warming by enhanced microbial activity.This work is part of the EU H2020 project &#8220;Nunataryuk&#8221;.

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Pesticides effect on soil microbial ecology and enzyme activity- An overview

Journal of Applied and Natural Science ◽

10.31018/jans.v8i2.929 ◽

2016 ◽

Vol 8 (2) ◽

pp. 1126-1132 ◽

Cited By ~ 7

Author(s):

Sanjay Arora ◽

Divya Sahni

Keyword(s):

Microbial Biomass ◽

Soil Microbial Biomass ◽

Soil Microbes ◽

Microbial Biomass Carbon ◽

Soil Microbial Communities ◽

Field Application ◽

Microbial Biomass C ◽

Microbial Biomass Nitrogen ◽

Soil Microbial ◽

Chemical Pesticides

In modern agriculture, chemical pesticides are frequently used in agricultural fields to increase crop production. Besides combating insect pests, these insecticides also affect the activity and population of beneficial soil microbial communities. Chemical pesticides upset the activities of soil microbes and thus may affect the nutritional quality of soils. This results in serious ecological consequences. Soil microbes had different response to different pesticides. Soil microbial biomass that plays an important role in the soil ecosystem where they have crucial role in nutrient cycling. It has been reported that field application of glyphosate increased microbial biomass carbon by 17% and microbial biomass nitrogen by 76% in nine soils at 14 days after treatment. The soil microbial biomass C increased significantly upto 30 days in chlorpyrifos as well as cartap hydrochloride treated soil, but thereafter decreased progressively with time. Soil nematodes, earthworms and protozoa are affected by field application rates of the fungicide fenpropimorph and other herbicides. Thus, there is need to assess the effect of indiscriminate use of pesticides on soil microorganisms, affecting microbial activity and soil fertility.

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Short-term effects on soil of biogas digestate, biochar and their combinations

Soil Research ◽

10.1071/sr18017 ◽

2018 ◽

Vol 56 (6) ◽

pp. 623 ◽

Cited By ~ 5

Author(s):

Roberto Cardelli ◽

Gabriele Giussani ◽

Fausto Marchini ◽

Alessandro Saviozzi

Keyword(s):

Microbial Biomass ◽

Antioxidant Capacity ◽

Biogas Production ◽

Co2 Production ◽

Microbial Biomass C ◽

Negative Effects ◽

Short Term ◽

Organic C ◽

Soil C ◽

Soil Microbial

The use of the residual material from waste aerobic digestion and biochar as amendments is currently discussed in the literature concerning the positive and negative effects on soil quality. We assessed the suitability of digestate (D) from biogas production and green biochar (B) to improve soil biological activity and antioxidant capacity and investigated whether there is an interaction between digestate and biochar applied to soil in combination. In a short-term (100-days) laboratory incubation, we monitored soil chemical and biological parameters. We compared soil amendments with 1% D (D1), 5% D (D5), 1% B (B), digestate–biochar combinations (D1+B and D5+B), and soil with no amendment. In D5, CO2 production, antioxidant capacity (TEAC), and dehydrogenase activity (DH-ase) and the contents of microbial biomass C, DOC and alkali-soluble phenols increased to the highest level. The biochar increased the total organic C (TOC) and TEAC of soil but decreased DOC, CO2 production, microbial biomass C, and DH-ase. The addition of biochar to digestate reduced soluble compounds (DOC and phenols), thus limiting the amount and activity of the soil microbial biomass (CO2 production and DH-ase). After 100 days of incubation D5+B showed the highest TOC content (82.8% of the initial amount). Both applied alone and in combination with digestate, the biochar appears to enrich the soil C sink by reducing CO2 emissions into the atmosphere.

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Repeated short-term organic amendments effects on physical and biological properties of a San Antón soil

The Journal of Agriculture of the University of Puerto Rico ◽

10.46429/jaupr.v100i2.12726 ◽

1969 ◽

Vol 100 (2) ◽

pp. 123-140

Author(s):

Ian C. Pagán-Roig ◽

Joaquín A. Chong ◽

José A. Dumas ◽

Consuelo Estévez de Jensen

Keyword(s):

Organic Matter ◽

Humic Acid ◽

Soil Organic Matter ◽

Microbial Biomass ◽

Organic Amendments ◽

Biological Properties ◽

Microbial Biomass C ◽

Microbial Biomass N ◽

Short Term ◽

Biomass N

The objective of this work was to measure the effects of repeated short-term organic amendments that we termed soil treatment management cycles (STMC) on physical and biological properties of a San Antón series soil. Each STMC lasted 60 days and consisted of incorporating 5% organic matter from coffee pulp compost; the planting, growth and incorporation of an intercrop of four green manure species; and the application of mycorrhizae and compost tea. The treatments were labeled: CL0, CL1, CL2 and CL3; where CL0 was the control, CL1 received one STMC, CL2 and CL3 received two and three STMC, respectively. The STMC intended to mimic the overall effect of a sustainable agricultural system, not to measure the individual effects of the practices. All treatments (CL1, CL2, CL3) showed an increase in soil organic matter (p≤0.05). When compared to the CL0 control, saturated hydraulic conductivity increased and bulk density decreased in all soils. Soil macroporosity was significantly increased by CL2 and CL3. Soil aggregate stability increased in CL1, CL2 and CL3 plots. Microbial biomass C increased in treatment CL3, and microbial biomass N increased in CL2 and CL3. The production of stable aggregates was correlated to humic acid content and positively influenced all other physical parameters assessed in this study. The STMC had a positive impact on soil properties by increasing the soil organic matter as well as the humic acid fraction. Soil macroporosity, defined as porosity with radius > 38 µm, was significantly increased by treatments CL2 and CL3. All of the organic matter fractions, including total organic matter, humic acid content, microbial biomass C and microbial biomass N were significantly increased by one or more STMC.

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Soil Microbial Community Response to Compost Addition to Nicosulfuron Contaminated Soil

Journal of Agricultural Studies ◽

10.5296/jas.v6i4.13945 ◽

2018 ◽

Vol 6 (4) ◽

pp. 49

Author(s):

Solomon A. Adejoro ◽

Ajoke C. Adegaye ◽

Doyinsola S. Sonoiki

Keyword(s):

Microbial Community ◽

Microbial Biomass ◽

Microbial Activity ◽

Soil Microbial Community ◽

Organic Fertilizer ◽

Community Response ◽

Herbicidal Activity ◽

Microbial Biomass C ◽

Mineral Fertilizers ◽

Soil Microbial

The toxicity of nicosulfuron to none target organisms is its downside, which has generated concerns about the herbicide in spite of its high herbicidal activity. Practices that would facilitate accelerated degradation of this herbicide will certainly be complementary to its use. A completely randomized design laboratory incubation experiment was carried out to examine the potentials of organic and mineral fertilizers to stimulate microbial activities in soil under the influence of the nicosulfuron herbicide. Soil contaminated with the field rate of nicosulfuron was separately amended with compost and NPK mineral fertilizer, and the treated samples were incubated for 56 days at room temperature. Soil microbial activity and microbial biomass C were measured in dynamics for the period of incubation. Eco-physiological quotients were also computed at the end of incubation to determine responses of soil microbes at the community level to the treatments. Application of nicosulfuron alone was found to repress both microbial biomass and microbial activity. Addition of fertilizer however caused these parameters to increase especially during the first 28 days after treatment application. The microbial metabolic quotient was raised by the soil amendments shortly after application with the exemption of NPK treated soil. However, only the soil samples in which compost was present lowered qCO2 at the termination of the experiment. NIC-COMP and NIC-NPK respectively raised and lowered the soil carbon mineralization quotient (qM) measured at the end of incubation. The soil microbial community was also found to be positively affected by the addition of fertilizers as indicated by the Cmic: Corg ratio and the microbial biomass change rate quotient (qC). It was therefore concluded that though the nicosulfuron herbicide at the field recommended rate has potentials to negatively affect the soil microbial community, application of organic fertilizer may help the soil to regain its microbial competence through enhanced degradation engendered by biostimulation of native microorganisms.

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Microbial biomass and activity in litter during the initial development of pure and mixed plantations of Eucalyptus grandis and Acacia mangium

Revista Brasileira de Ciência do Solo ◽

10.1590/s0100-06832013000100008 ◽

2013 ◽

Vol 37 (1) ◽

pp. 76-85 ◽

Cited By ~ 12

Author(s):

Daniel Bini ◽

Aline Fernandes Figueiredo ◽

Mylenne Cacciolari Pinheiro da Silva ◽

Rafael Leandro de Figueiredo Vasconcellos ◽

Elke Jurandy Bran Nogueira Cardoso

Keyword(s):

Microbial Biomass ◽

Microbial Activity ◽

Eucalyptus Grandis ◽

Acacia Mangium ◽

Soil Nutrient ◽

Microbial Biomass C ◽

Senescent Leaf ◽

Soil C ◽

Nutrient Contents ◽

Leaf Drop

Studies on microbial activity and biomass in forestry plantations often overlook the role of litter, typically focusing instead on soil nutrient contents to explain plant and microorganism development. However, since the litter is a significant source of recycled nutrients that affect nutrient dynamics in the soil, litter composition may be more strongly correlated with forest growth and development than soil nutrient contents. This study aimed to test this hypothesis by examining correlations between soil C, N, and P; litter C, N, P, lignin content, and polyphenol content; and microbial biomass and activity in pure and mixed second-rotation plantations of Eucalyptus grandis and Acacia mangium before and after senescent leaf drop. The numbers of cultivable fungi and bacteria were also estimated. All properties were correlated with litter C, N, P, lignin and polyphenols, and with soil C and N. We found higher microbial activity (CO2 evolution) in litter than in soil. In the E. grandis monoculture before senescent leaf drop, microbial biomass C was 46 % higher in litter than in soil. After leaf drop, this difference decreased to 16 %. In A. mangium plantations, however, microbial biomass C was lower in litter than in soil both before and after leaf drop. Microbial biomass N of litter was approximately 94 % greater than that of the soil in summer and winter in all plantations. The number of cultivable fungi and bacteria increased after leaf drop, especially so in the litter. Fungi were also more abundant in the E. grandis litter. In general, the A. mangium monoculture was associated with higher levels of litter lignin and N, especially after leaf drop. In contrast, the polyphenol and C levels in E. grandis monoculture litter were higher after leaf drop. These properties were negatively correlated with total soil C and N. Litter in the mixed stands had lower C:N and C:P ratios and higher N, P, and C levels in the microbial biomass. This suggests more effective nutrient cycling in mixed plantations in the long term, greater stimulation of microbial activity in litter and soil, and a more sustainable system in general.

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Microbial activity and survival in soils dried at different rates

Soil Research ◽

10.1071/sr9920209 ◽

1992 ◽

Vol 30 (2) ◽

pp. 209 ◽

Cited By ~ 50

Author(s):

AW West ◽

GP Sparling ◽

CW Feltham ◽

J Reynolds

Keyword(s):

Microbial Biomass ◽

Water Content ◽

Microbial Activity ◽

Initial Period ◽

Organic Matter Content ◽

Matter Content ◽

Survival Strategies ◽

Microbial Biomass C ◽

Organic C ◽

Microbial C

The changes in microbial biomass C, soil respiration, microbial activity (respiration/microbial C) and the content of oxidizable organic C extracted by 0-5 M K2SO4, were measured in four soils of contrasting characteristics (a sand, two silt loam soils and a peat) which were air-dried at 22�C at three different rates in the laboratory. Respiration was also measured on samples of the drying soils rewetted with water. The rates of drying were: <10 h (fast), <33 h (medium) and <62 h (slow); drying was carried out for 6 h on consecutive days, with overnight storage. Measurements were also made on soils stored at field-moisture content over the 15 day duration of the experiment. Respiration and activity declined continuously and in a generally linear manner as the volumetric water content (W,) decreased. The decline in respiration in relation to water content W, was similar for all four soils and for the three rates of drying. Microbial biomass C also declined but generally only after a considerable initial period of drying (after the soils had reached Wv of 0-1-0.3). Extractable C values increased, but only after an initial drying period (Wv below 0.06-0.12). The increases in extractable C were approximately coincident with the decreases in microbial C, but only part of the increase in extractable C could be accounted for by the decrease in microbial C. Rewetting of dried soils caused a marked increase in respiration, particularly when the rewetted soils had reached Wv values where extractable C had begun to increase. The relationship between microbial activity and extractable C was similar for all four soils and was not affected by the rate of drying. The similarity of the microbial responses in these contrasting soils, and the absence of any detectable differences between rates of drying suggest that the microbial communities had similar survival strategies to resist desiccation, and occupied comparable physical niches in the soils, despite these soils having widely differing textures, organic matter content, and soil moisture characteristics.

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Short-term effects of organic municipal wastes on wheat yield, microbial biomass, microbial activity, and chemical properties of soil

Biology and Fertility of Soils ◽

10.1007/s00374-011-0620-y ◽

2011 ◽

Vol 48 (2) ◽

pp. 205-216 ◽

Cited By ~ 51

Author(s):

Víctor G. Franco-Otero ◽

Pedro Soler-Rovira ◽

Diana Hernández ◽

Esther G. López-de-Sá ◽

César Plaza

Keyword(s):

Microbial Biomass ◽

Microbial Activity ◽

Wheat Yield ◽

Chemical Properties ◽

Short Term ◽

Properties Of Soil ◽

And Chemical Properties ◽

Short Term Effects

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Biochar Impacts on Acidic Soil from Camellia Oleifera Plantation: A Short-Term Soil Incubation Study

Agronomy ◽

10.3390/agronomy10091446 ◽

2020 ◽

Vol 10 (9) ◽

pp. 1446

Author(s):

Qianqian Song ◽

Yifan He ◽

Yuefeng Wu ◽

Shipin Chen ◽

Taoxiang Zhang ◽

...

Keyword(s):

Microbial Biomass ◽

Enzymatic Activity ◽

Soil Nutrients ◽

Soil Ph ◽

Soil Amendment ◽

Microbial Biomass C ◽

Microbial Biomass N ◽

Short Term ◽

Variable Effect ◽

Soil Enzymatic Activity

Nowadays, biochar is increasingly used widely as an important soil amendment to enhance soil nutrients availability. Therefore, we investigated the effect of C.oleifera shell biochar (CSB) on C.oleifera plantation soils to provide evidence that C. oleifera shell as a raw material in biochar has great potential to be a soil amendment. For this, a short-term incubation experiment was conducted in controlled conditions to evaluate the effects of CSB application on two soil chemical properties, microbial biomass, and enzymatic activity. We compared two acidic soils, mixed with CSB of three pyrolysis temperatures (300, 500, and 700 °C), and two application rates (3% and 5% (w/w)), incubated for 180 days. The results showed that the soil pH, total P (TP), and available P (AP) significantly increased under 5CSB700 in two soils, and indicated CSB application rate and pyrolysis temperature had a significant impact on soil pH, TP, and AP (p < 0.05). CSB application also significantly increased the total inorganic P in two soils and presented a significantly positive correlation with soil pH, TP, and AP under redundancy analysis. The results suggested that CSB application has a variable effect on soil enzymatic activity, microbial biomass C (MBC), and microbial biomass P (MBP) on average, while it increased the soil microbial biomass N (MBN) in both soils. We concluded that CSB could be a soil amendment to increase soil nutrients of C.oleifera plantation soils. Before the application of biochar to C.oleifera plantation forest soils, long-term studies are required to assess the effects of biochar under field conditions and its promoting effect on the growth of C. oleifera.

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Addition of glucose increases the activity of microbes in saline soils

Soil Research ◽

10.1071/sr13104 ◽

2014 ◽

Vol 52 (6) ◽

pp. 568 ◽

Cited By ~ 1

Author(s):

Bannur Elmajdoub ◽

Petra Marschner ◽

Richard G. Burns

Keyword(s):

Microbial Biomass ◽

Microbial Activity ◽

Negative Impact ◽

Microbial Biomass C ◽

Saline Soils ◽

Soluble Nitrogen ◽

Available N ◽

Percentage Decrease ◽

Biomass Turnover ◽

Negative Effect

Adaptation of soil microbes to salinity requires substantial amounts of energy. We hypothesised that addition of glucose would increase microbial activity and growth and alleviate the negative effect of salinity on microbes. An incubation experiment was conducted with four salinity levels by using one non-saline and three saline soils of similar texture (sandy clay loam), with electrical conductivities (EC1:5) of 0.1, 1.1, 3.1 and 5.2 dS m–1. Glucose was added to achieve five organic carbon concentrations (0, 0.5, 1, 2.5, 5 g C kg–1). Soluble nitrogen (N) and phosphorus (P) were added to achieve a carbon (C) : N ratio of 20 and a C : P ratio of 200 to ensure that these nutrients did not limit microbial growth. A water content of 50% of the water-holding capacity (optimal for microbial activity in soils of this texture) was maintained throughout the incubation. Soil respiration was measured continuously over 21 days; microbial biomass C and available N and P were determined on days 2, 5, 14 and 21. Cumulative respiration was increased by addition of glucose and was reduced by salinity. The percentage decrease in cumulative respiration in saline soils compared with non-saline soil was greatest in the unamended soil and lowest with addition of 5 g C kg–1. At this rate of C addition, the percentage decrease in cumulative respiration increased with increasing salinity level. Microbial biomass C (MBC) concentration on days 2 and 5 was strongly increased by ≥1 g C kg–1 but decreased over time with the strongest decrease at the highest C addition rate. The MBC concentration was negatively correlated with EC at all C rates at each sampling date. Addition of C resulted in N and P immobilisation in the first 5 days. Biomass turnover as a result of depletion of readily available C released previously immobilised N and P after day 5, particularly in the soils with low salinity. This study showed that over a period of 3 weeks, addition of glucose increased microbial activity and growth in saline soils and alleviated the negative impact of salinity on microbes.

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Changes in microbial biomass and organic matter levels during the first year of modified tillage and stubble management practices on a red earth

Soil Research ◽

10.1071/sr9941339 ◽

1994 ◽

Vol 32 (6) ◽

pp. 1339 ◽

Cited By ~ 45

Author(s):

V Gupta ◽

MM Roper ◽

JA Kirkegaard ◽

JF Angus

Keyword(s):

Organic Matter ◽

Microbial Biomass ◽

Microbial Activity ◽

Management Practices ◽

Microbial Respiration ◽

Microbial Biomass C ◽

First Year ◽

Tillage Practices ◽

Red Earth

Farming practices involving stubble burning and excessive tillage in Australia have led to losses of organic matter from the soil. Crop residue retention and reduced tillage practices can reverse these trends, but changes in organic matter levels are evident only after a long term. Microbial biomass (MB), the living portion of soil organic matter, responds rapidly to changes in soil and crop management practices. We evaluated changes in microbial biomass and microbial activity in the first year following the modification of stubble management and tillage practices on a red earth near Harden, New South Wales. Following an oat crop harvested late in 1989, seven treatments involving stubble and tillage management were applied in February 1990. Wheat was planted in May 1990. Measurements of total organic carbon (C) and total nitrogen (N) in the top 15 cm of soil indicated no significant changes after 1 year, although there was a significant effect on the distribution of C and N. However, significant changes in MB were observed in the first year. Microbial biomass C in the top 5 cm of the soil ranged from 25 to 52 g C m-2 and these levels dropped by 50% or more with each 5 cm depth. Implementation of treatments altered MB, particularly in the top 5 cm where MB-C and MB-N were significantly greater in stubble-retained than in the top 5 cm where MB-C and MB-N were significantly greater in stubble-retained than in the stubble-burnt treatments, and in the direct drill treatment than in the stubble-incorporated treatment. Microbial biomass in soil increased during the growth of wheat in all treatments, but this was slower in the standing stubble-direct drill treatment, probably due to the delay in the decomposition of stubble. Microbial respiration, which was concentrated in the surface 5 cm of soil in all treatments, was greatest in the direct drill treatments. Microbial activity below 5 cm was higher with stubble incorporation than with direct drill. Specific microbial activity (microbial respiration per unit MB) had the greatest response to tillage at 10-15 cm depth. Microbial quotients (MB as a percentage of C or N) responded to changes in tillage but not significantly to stubble retention. Our studies, during the first year following the modification of stubble management and tillage practices, suggested that changes in MB and microbial activity may be sensitive and reliable indicators of long-term changes in organic matter in soils.

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