Microbial activity in gradually dried or rewetted soils as governed by water and substrate availability

Soil Research ◽  
1989 ◽  
Vol 27 (4) ◽  
pp. 747 ◽  
Author(s):  
AW West ◽  
GP Sparling ◽  
TW Speir
Keyword(s):  
Microbial Respiration ◽  
Annual Rainfall ◽  
Silt Loam ◽  
Moisture Regimes ◽  
Substrate Induced Respiration ◽  
Qualitative Nature ◽  
Micro Organisms ◽  
Gravimetric Water Content ◽  
Microbial Mass ◽  
Better Than

Microbial respiration, mass and activity (respiration/mass) in three silt loam soils with different moisture regimes (1000-2700 mm annual rainfall) were measured as the field-moist soils were gradually air-dried at 25�C in the laboratory. Microbial CO2 and O2 respiration and mass (estimated from substrate-induced respiration), and oxidizable organic carbon, extractable in 0.5 M K2SO4, were monitored throughout the 60 h drying period and also in samples of these gradually dried soils which were rewetted with water (2 ml g-1 soil). Water availability was the major factor controlling microbial respiration and activity as the soils dried. Both respiration and activity declined continuously as gravimetric water content (W) decreased. Microbial mass also declined, but only after W fell below 0.1-0.3. The microbial mass of the lowest-rainfall soil resisted desiccation better than the higher-rainfall soils. Extractable carbon levels increased after considerable soil drying (when W < 0.1-0.2). This increase in extractable carbon could be accounted for by the carbon released from micro-organisms killed by drying. Microbial respiration and activity increased sharply within 30 min of rewetting gradually dried soils. These increases appeared to be largely due to the carbon released from micro-organisms, killed by drying, being metabolized by the surviving micro-organisms when water was present. The ability of the surviving micro-organisms to metabolize this (extractable) carbon was remarkably similar for all three soils, suggesting that the carbon released from killed cells is of a very similar qualitative nature, and/or that the surviving populations were also similar between the soils.

Dynamics of microbial-C, N-flush and ATP, and enzyme activities of gradually dried soils from a climosequence

Soil Research ◽  
1988 ◽  
Vol 26 (3) ◽  
pp. 519 ◽  
Author(s):  
AW West ◽  
GP Sparling ◽  
TW Speir ◽  
JM Wood
Keyword(s):  
Annual Rainfall ◽  
Silt Loam ◽  
Strongly Correlated ◽  
Total Change ◽  
Moisture Regimes ◽  
Substrate Induced Respiration ◽  
C And N ◽  
Microbial C ◽  
Soil Phosphatase ◽  
Microbial N

Three silt loam soils from a climosequence (1000-2700 mm annual rainfall) were gradually dried from field moisture content to air-dryness at 25�C in the laboratory. Microbial C measured by substrate-induced respiration (SIR), fumigation-incubation (FI) or fumigation-extraction (FE), microbial N-flush measured by FI and FE, microbial ATP content and soil phosphatase and sulfatase activities were monitored throughout the drying period (approx. 60 h). All indices declined as the gravimetric soil water content (W) decreased until reaching air-dryness. Significant declines in the biomass sometimes occurred only following a large decrease in W, dependent on the soil. In general, when microbial C and N-flush declined, the rates of decline were linearly correlated with W. However, ATP and soil phosphatase were exponentially related to W. When expressed as a ratio of the total change in microbial indices against the total change in W for the whole drying period, the ratios were consistent between the soils. Agreement between the SIR and FE estimates of microbial C, whilst significant (r = 0 58***), was poor, especially for the low rainfall soil, although the FE C- and N-flushes correlated well (r = 0-76***). In contrast, the FI C- and N-flushes correlated very poorly (r = 0.30**) and were not significantly correlated with W or the other indices. ATP and soil phosphatase activity were strongly correlated (r = 0.89***). The reliability of the methods and the influence of soil moisture regimes on microbial survival are discussed.

THE ROLE OF GRASSLAND IN MANAGEMENT

1968 ◽  
pp. 44-49
Author(s):  
B.K. Cameron
Keyword(s):  
Soil Temperature ◽  
Annual Rainfall ◽  
Silt Loam ◽  
Average Annual Rainfall ◽  
Very High ◽  
Wilting Point

THE PROPERTY to be discussed is a mixed sheep and cropping unit, situated ei ht a miles east of Ashburton and midway between the Ra aia and the Ashburton rivers. Average annual rainfall is 27 in., evenly spread, but there is very high summer evaporation and therefore frequent droughts. On average, the soil is below wilting point for 40 to 50 days each summer. Winters are cold with the soil temperature being below 48°F for about four months each year. The soil is a Lismore stony silt loam averaging 9 in. in depth over gravel.

scholarly journals Enhancement of Biodegradation of Palm Oil Mill Effluents by local Isolated Fungi

2016 ◽  
Vol 15 (4) ◽  
pp. 23-34 ◽  
Author(s):  
F T Z Jabeen ◽  
J V Shreevathsa
Keyword(s):  
Chemical Oxygen Demand ◽  
Effective Treatment ◽  
Palm Oil ◽  
Biochemical Oxygen Demand ◽  
Oxygen Demand ◽  
Palm Oil Mill Effluent ◽  
Physicochemical Quality ◽  
Palm Oil Mill ◽  
Micro Organisms ◽  
Better Than

This study was designed to investigate the fungi associated with palm oil mill effluent (POME) in Gulur village of Tumkur. Biodegradation of palm oil mill effluents was conducted to measure the discarded POME based on physicochemical quality. The fungi that were isolated are Aspergillusniger, A. flavus, A. fumigatus, A. ochraceus, Rhizopussp, Peniciliumsp and Trichodermavirde. The autoclaved and unautoclaved raw POME samples were incubated for 7 days and the activities of the fungi were observed each for 12 hours. The supernatants of the digested POME were investigated for the removal of chemical oxygen demand (COD), color (ADMI), and biochemical oxygen demand (BOD) at the end of each digestion cycle. The results showed that the unautoclaved raw POME sample degraded better than the inoculated POME sample and this suggests that the microorganisms that are indigenous in the POME are more effective than the introduced micro-organisms. This result, however, indicates the prospect of isolating indigenous microorganisms in the POME for effective biodegradation of POME. Moreover, the effective treatment of POME yields useful products such as reduction of BOD, COD, and color.

Effectiveness of Starch Xanthide Formulations of Chloramben for Weed Control in Pumpkin (Cucurbita moschata)

Weed Science ◽  
1982 ◽  
Vol 30 (2) ◽  
pp. 169-174 ◽  
Author(s):  
Victor Raboy ◽  
Herbert J. Hopen
Keyword(s):  
Weed Control ◽  
Sandy Soil ◽  
Growing Season ◽  
Silt Loam ◽  
Cucurbita Moschata ◽  
Release Rates ◽  
Emulsifiable Concentrate ◽  
Loam Soil ◽  
In Parenthesis ◽  
Better Than

The persistence and effectiveness in pumpkin [Cucurbita moschata(Puch.) Poir.] weed control of several starch xanthide (SX) and commercial formulations of the ammonium (NH3) salt and methyl (CH3) ester of chloramben (3-amino-2,5-dichlorobenzoic acid) were studied in the laboratory and field. The soluble concentrate (SC) of chloramben NH3salt and the emulsifiable concentrate (EC) of chloramben CH3ester controlled weeds throughout the growing season on a silt loam soil. SC chloramben NH3salt was not effective, and EC chloramben CH3ester was inconsistent in weed control on sandy soil. Manipulation of the SX formulation produced products with slow, uniform release rates. The release rates (crosslinking reagent in parenthesis) rank as follows, from fastest to slowest: SX(Ca2+) CH3ester = SX(H2O2) acid > SX(H2O2) CH3ester > SX(Fe3+) acid > SX(Fe3+) CH3ester. In trials on silt loam and sand, SX formulations did not control weeds better than EC chloramben CH3ester.

Summer dormancy, regeneration and persistence of perennial grasses in south-western Australia

1977 ◽  
Vol 17 (88) ◽  
pp. 795 ◽  
Author(s):  
EF Biddiscombe ◽  
AL Rogers ◽  
RA Maller
Keyword(s):  
Western Australia ◽  
Festuca Arundinacea ◽  
Late Summer ◽  
Perennial Grasses ◽  
Annual Rainfall ◽  
Internal Drainage ◽  
Plant Mortality ◽  
Podzolic Soils ◽  
Summer Dormancy ◽  
Better Than

Autumn growth and persistence of periodically grazed, spaced plant swards of eleven perennial grasses were measured at two sites registering 750 mm and 1120 mm annual rainfall respectively. The grasses were grown on gravelly podzolic soils of moderate internal drainage and depth of A horizon. After the third summer, autumn regrowth was generally better in Phalaris tuberosa lines than in lines of Dactylis glomerata, Festuca arundinacea and Lolium perenne, Festuca arundinacea cv. Melik and D. glomerata cv. Currie regenerated better than P. tuberosa lines in the first two autumn seasons at the drier site. Capacity for autumn growth appeared to be associated mainly with the level of dormancy achieved by basal buds at mid-summer, though relatively high dormancy of one or two lines at the drier site did not prevent significant plant mortality. Numbers of reproductive tillers per plant in spring and active basal buds per tiller in late summer were less important traits affecting the growth of some lines. We think that rankings for summer dormancy would be useful for screening future introductions for wetter parts (> 750 mm annual rainfall) of the south-western region of Western Australia.

scholarly journals Phosphorus and faecal bacteria in runoff from horse paddocks and their mitigation by the addition of P-sorbing materials

2012 ◽  
Vol 21 (3) ◽  
pp. 247-259 ◽  
Author(s):  
Jaana Uusi-Kämppä ◽  
Aaro Närvänen ◽  
Janne Kaseva ◽  
Håkan Jansson
Keyword(s):  
Drainage Water ◽  
Rainfall Simulation ◽  
Faecal Coliforms ◽  
Ph Changes ◽  
Faecal Bacteria ◽  
Micro Organisms ◽  
Better Than ◽  
Percolation Water

The growing popularity of horse keeping is accompanied by an increase of phosphorus (P) and faecal micro-organisms from outdoor paddocks. We used an indoor rainfall simulation to monitor  concentrations of dissolved reactive P (DRP) and faecal coliforms in runoff and percolation water from different paddock footings. Drainage water was also monitored from two paddocks constructed of woodchips. Sand retained more DRP (p<0.0001) and coliforms from percolation water than woodchips. Some of the footings were amended with P-sorbing materials, such as [Ca(OH)2], [Fe2(SO4)3], or Fe-gypsum, to retain DRP. High DRP concentrations (17–18 mg l-1) were observed in runoff from a woodchip footing amended earlier with Ca(OH)2 and in sand footing amended with CaCO3. However, application of Fe-gypsum to woodchips decreased the DRP load in percolation water by 83% compared to the footing without Fe-gypsum. Fe compounds were better than Ca compounds. The decrease in coliforms was usually small due to the modest pH changes in the water.

Campylobacter Peritonitis Complicating Continuous Ambulatory Peritoneal Dialysis: Report of Three Cases and Review of the Literature

2010 ◽  
Vol 30 (1) ◽  
pp. 99-104 ◽  
Author(s):  
Sittana S. Elshafie ◽  
Muhammad Asim ◽  
Adel Ashour ◽  
Abdul Haleem Elhiday ◽  
Thoraya Mohsen ◽  
...  
Keyword(s):  
Peritoneal Dialysis ◽  
Continuous Ambulatory Peritoneal Dialysis ◽  
Molecular Techniques ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Culture Techniques ◽  
Oxidase Test ◽  
Campylobacter Species ◽  
Micro Organisms ◽  
Better Than

BackgroundThe micro-organisms involved in continuous ambulatory peritoneal dialysis (CAPD) peritonitis are usually gram-positive cocci of cutaneous origin. Campylobacter species are rarely implicated as a cause of CAPD peritonitis.MethodsA retrospective review of 100 consecutive episodes of peritonitis was carried out in patients undergoing CAPD or automated PD in our hospital from June 2004 to December 2007. Collection of dialysate and microbial examination was done according to ISPD guidelines. Identification of the organism was made on the basis of Gram smear morphology, positive oxidase test, and biochemical reactions using API Campi (BioMérieux, Marcy l'Étoile, France). Susceptibility testing was performed using E-test (AB Biodisc, Solna, Sweden) and confirmation was done by molecular techniques.ResultsThe causative organisms in 23 of these episodes were gram-negative bacteria, 3 of which were identified as Campylobacter species using special culture techniques. The clinical presentation in our patients with Campylobacter peritonitis (CP) was different from that of patients with peritonitis from other organisms in that all 3 had diarrhea at presentation. Among patients with CP, no subspecies-specific feature was identified. Good response to the antibiotic treatment was observed; there was no relapse/recurrence of peritonitis, catheter loss, or death.ConclusionIncidence of CP remains low and, regardless of the subtype, clinical outcomes are better than those seen with other gram-negative bacteria such as Pseudomonas. The presence of diarrhea at presentation and the finding of curved or spiral gram-negative bacilli in the Gram smear of peritoneal dialysis effluent should make one think of CP. The use of appropriate microbiology techniques in this situation will increase the isolation of this organism.

Effects of Metolachlor Residues on Rice (Oryza sativa)

Weed Science ◽  
1985 ◽  
Vol 33 (6) ◽  
pp. 819-824 ◽  
Author(s):  
Michael P. Braverman ◽  
Terry L. Lavy ◽  
Ronald E. Talbert
Keyword(s):  
Oryza Sativa ◽  
Field Studies ◽  
Rice Seed ◽  
Silt Loam ◽  
Seeding Rate ◽  
Better Than

Field studies were conducted on a Taloka silt loam (Mollic Albaqualf) to determine the effects of residual levels of metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] on rice (Oryza sativaL.). Yield reductions could be overcome by increasing rice seeding rate, by decreasing seeding depth, or by applying the safeners CGA-43089 [α-(cyanomethoxyimino)-benzacetonitrile] or CGA-92194 [α-(1,3-dioxolan-2-yl-methoximino)-benzacetonitrile] to the rice seed. Greenhouse studies with the safeners and reduced seeding depths indicated that CGA-92194 was better than CGA-43089 for protecting rice from metolachlor injury, but reduced seeding depths did not reduce metolachlor injury.

Early Peritonitis in A Large Peritoneal Dialysis Provider System in Colombia

2017 ◽  
Vol 37 (1) ◽  
pp. 30-34 ◽  
Author(s):  
Edgar Vargas ◽  
Peter G. Blake ◽  
Mauricio Sanabria ◽  
Alfonso Bunch ◽  
Patricia López ◽  
...  
Keyword(s):  
Peritoneal Dialysis ◽  
Provider Network ◽  
Key Factor ◽  
Incidence Risk ◽  
Observational Cohort ◽  
Therapy Services ◽  
Micro Organisms ◽  
First 90 Days ◽  
Better Than

BackgroundPeritonitis is the most important complication of peritoneal dialysis (PD), and early peritonitis rate is predictive of the subsequent course on PD. Our aim was to calculate the early peritonitis rate and to identify characteristics and predisposing factors in a large nationwide PD provider network in Colombia.MethodsThis was a historical observational cohort study of all adult patients starting PD between January 1, 2012, and December 31, 2013, in 49 renal facilities in the Renal Therapy Services in Colombia. We studied the peritonitis rate in the first 90 days of treatment, its causative micro-organisms, its predictors and its variation with time on PD and between individual facilities.ResultsA total of 3,525 patients initiated PD, with 176 episodes of peritonitis during 752 patient-years of follow-up for a rate of 0.23 episodes per patient year equivalent to 1 every 52 months. In 41 of 49 units, the rate was better than 1 per 33 months, and in 45, it was better than 1 per 24 months. Peritonitis rates did not differ with age, ethnicity, socioeconomic status, or PD modality. We identified high incidence risk periods at 2 to 5 weeks after initiation of PD and again at 10 to 12 weeks.ConclusionAn excellent peritonitis rate was achieved across a large nationwide network. This occurred in the context of high nationwide PD utilization and despite high rates of socioeconomic deprivation. We propose that a key factor in achieving this was a standardized approach to management of patients.

QUALITATIVE STUDIES OF SOIL MICRO-ORGANISMS: III. INFLUENCE OF PLANT GROWTH ON THE CHARACTER OF THE BACTERIAL FLORA

1940 ◽  
Vol 18c (2) ◽  
pp. 42-53 ◽  
Author(s):  
A. G. Lochhead
Keyword(s):  
Physiological Activity ◽  
Bacterial Flora ◽  
Soil Microflora ◽  
Pronounced Increase ◽  
The Family ◽  
Qualitative Nature ◽  
Selective Plating ◽  
Genus Corynebacterium ◽  
Micro Organisms

Comparative studies of the relative incidence of bacterial types occurring in the rhizosphere of different plants and in control soils indicated that the qualitative nature of the soil microflora is markedly influenced by the growing plant. In the rhizosphere Gram-negative rods are proportionately increased while Gram-positive rods, coccoid rods, and spore-forming types are relatively less abundant.The majority of bacteria isolated from soil by non-selective plating are forms included in the family Proactinomycetaceae (Jensen's classification). Of these by far the largest group consists of members of the genus Corynebacterium. In the rhizosphere proactinomycetes as a whole are relatively less abundant, with the Corynebacterium (non-motile) group likewise depressed. However, closely related motile forms classed as Mycoplana are preferentially stimulated.In the rhizosphere the bacteria show definitely greater physiological activity than in soil distant from the plant. Not only is there a notably greater proportion of motile forms, and a pronounced increase in the incidence of chromogenic types, but also a higher incidence of liquefying bacteria and of those able to affect glucose.A comparison of the rhizosphere of certain plant varieties resistant and susceptible respectively to soil-borne disease showed differences of a qualitative nature in the bacterial flora suggestive of a greater "rhizosphere effect" in the case of the susceptible varieties studied. Results point to the possibility that resistance may be associated with a selective action of root excretions on the saprophytic soil microflora.

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