Intact soil-core microcosms compared with multi-site field releases for pre-release testing of microbes in diverse soils and climates

2001 ◽  
Vol 47 (3) ◽  
pp. 237-252 ◽  
Author(s):  
Joel V Gagliardi ◽  
J Scott Angle ◽  
James J Germida ◽  
R Campbell Wyndham ◽  
Christopher P Chanway ◽  
...  
Keyword(s):  
Low Cost ◽  
Soil Microbiology ◽  
Soil Core ◽  
Wheat Roots ◽  
Fallow Soil ◽  
Site Field ◽  
Intact Soil Core ◽  
Regression Slopes ◽  
Field Plots ◽  
Intact Soil

Intact soil-core microcosms were used to compare persistence of Pseudomonas chlororaphis 3732RN-L11 in fallow soil and on wheat roots with field releases at diverse sites. Parallel field and microcosm releases at four sites in 1996 were repeated with addition of one site in 1997. Microcosms were obtained fresh and maintained at 60% soil water holding capacity in a growth chamber at 70% relative humidity, a 12-hour photoperiod, and constant temperature. Persistence of 3732RN-L11 was measured at each site in field plots and microcosms at 7–21 day intervals, and in duplicate microcosms sampled at an independent laboratory. Linear regression slopes of field plot and microcosm persistence were compared for each site, and between identical microcosms sampled at different sites, using log10transformed plate counts. Microcosm persistence closely matched field plots for wheat roots, but persistence in fallow soil differed significantly in several instances where persistence in field plots was lower than in microcosms. Analysis of weather variations at each site indicated that rainfall events of 30–40 mm caused decreased persistence in fallow soil. Cooler temperatures enhanced persistence in field plots at later time points. Inter-laboratory comparison of regression slopes showed good agreement for data generated at different sites, though in two instances, longer sampling periods at one site caused significant differences between the sites. Soil characteristics were compared and it was found that fertility, namely the carbon to nitrogen ratio, and the presence of expanding clays, were related to persistence. These microcosm protocols produced reliable data at low cost, and were useable for pre-release risk analyses for microorganisms.Key words: microcosm, soil, microbiology, risk assessment, 3732RN-L11.

MEASUREMENT OF EVAPORATION FROM SOIL BENEATH CROP CANOPIES

1983 ◽  
Vol 63 (1) ◽  
pp. 137-141 ◽  
Author(s):  
G. K. WALKER
Keyword(s):  
Zea Mays ◽  
Key Words ◽  
Leaf Area ◽  
Energy Supply ◽  
Zea Mays L ◽  
Growing Season ◽  
Soil Core ◽  
Crop Cover ◽  
Intact Soil Core ◽  
Intact Soil

Evaporation rates beneath maize canopies were measured using an intact soil core technique. Early in the growing season evaporation rates were periodically high (4.0 mm∙day−1) following rain, but declined rapidly. At full crop cover, when energy supply normally limits evaporation, significant differences in evaporation were detected between canopies with leaf area indices of 3.0 and 4.0. Key words: Evaporation measurement, energy supply, Zea mays L., leaf area, soil evaporimeter, lysimeter

Field Extraction of Large Intact Soil Cores for Leaching Studies in the Laboratory

1996 ◽  
Vol 10 (1) ◽  
pp. 210-216 ◽  
Author(s):  
She-Kong Chong ◽  
Suling Zhao ◽  
Brian P. Klubek
Keyword(s):  
Hydraulic Conductivity ◽  
Low Cost ◽  
Sampling Procedure ◽  
Soil Horizon ◽  
Soil Core ◽  
Soil Cores ◽  
Intact Soil Cores ◽  
Large Soil ◽  
Intact Soil

Various samplers have been developed for taking intact soil cores. Very often, the sampler was used once or twice to take only a few soil cores then it became either obsolete or a burden for maintenance and storage. An economic portable hand-operated soil core sampler was developed to obtain large soil cores with a diameter of 19 cm and a length of 120 cm. The quality of large soil cores was evaluated and compared with that obtained from short cores from each soil horizon. In addition, the large intact column was used to evaluate atrazine transport under the saturated condition. Results showed that the hydraulic conductivity of the large cores were of the same magnitude as that of short cores, except for the A horizon; the hydraulic conductivity of the large cores was about 10 times greater than the short cores. Even though the sampling procedure is labor intensive, the soil sampler has the flexibility to collect different size soil cores and can be constructed at a very low cost (less than $200 including labor). Lastly, the sampler is maintenance free and can be stored easily in a limited space.

EFFECT OF CROP DEBRIS, PLANT ROOTS, AND CROP SEQUENCE ON THE MICROBIAL FLORA OF THE SOIL IN RELATION TO ROOT ROT IN CEREAL CROPS

1948 ◽  
Vol 26c (1) ◽  
pp. 86-93 ◽  
Author(s):  
L. E. Tyner
Keyword(s):  
Barley Straw ◽  
Wheat Roots ◽  
Wheat Seedlings ◽  
Fallow Soil ◽  
Helminthosporium Sativum ◽  
Plate Counts ◽  
Oat Straw ◽  
Field Plots ◽  
Penicillium Spp ◽  
Crop Sequence

The decomposition of wheat, oat, or barley straw in soil caused a marked increase in the microflora, as indicated by plate counts. The oat straw compost yielded significantly more colonies of fungi than either the wheat or barley straw composts. The population of bacteria and actinomycetes was increased to about the same degree by all three of the composts.In another laboratory experiment, wheat, oats, barley, and beans were planted in various rotations in pots of soil from field plots known to be heavily infested with the root-rotting pathogens Helminthosporium sativum P. K. and B., Ophiobolus graminis Sacc., and Fusarium spp. Fungi, mostly Penicillium spp. and Mucor spp., were up to 15 times more abundant from the rhizosphere of wheat roots than from the rhizosphere of oat, barley, or bean roots, regardless of crop sequence. It is assumed that the higher counts of saprophytic fungi obtained from the rhizosphere of wheat seedlings were directly correlated with the greater amount of dead root tissue on this crop, since disease on the wheat seedlings was more severe than on the other hosts. In a duplicate experiment in fallow soil, the rhizospheres of wheat, oats, barley, and beans yielded about equal numbers of fungi.

Determining the environmental fate of a filamentous fungus,Trichoderma reesei, in laboratory-contained intact soil-core microcosms using competitive PCR and viability plating

2004 ◽  
Vol 50 (8) ◽  
pp. 623-631 ◽  
Author(s):  
Miguel A Providenti ◽  
Selma I Mautner ◽  
Omar Chaudhry ◽  
Manon Bombardier ◽  
Richard Scroggins ◽  
...  
Keyword(s):  
Environmental Fate ◽  
Polymerase Chain Reaction Analysis ◽  
Genetically Engineered ◽  
Winter Period ◽  
Soil Core ◽  
Competitive Pcr ◽  
Trichoderma Spp ◽  
Soil Dna ◽  
Intact Soil Core ◽  
Intact Soil

Trichoderma spp. are used extensively in industry and are routinely disposed of in landfill sites as spent biomass from fermentation plants. However, little is known regarding the environmental fate of this biomass. We tracked the survival of T. reesei strain QM6A#4 (a derivative of strain QM6A marked with a recombinant construct) over a 6-month period in laboratory-contained, intact soil-core microcosms incubated in a growth chamber. Survival was tested in 3 different soils and the effect of a plant rhizosphere (bush lima beans, Phaseolus limensis) was investigated. Levels and viability of the fungus were determined, respectively, by quantitative competitive polymerase chain reaction analysis of total soil DNA extracts and dilution-plating of soil on a semiselective growth medium. Whereas chemically killed QM6A#4 became undetectable within 3 d, QM6A#4 added as a live inoculum decreased ~4- to ~160-fold over the first 1–3 months and then reached a steady state. After 4 months, soil cores were subjected to a 1.5-month simulated winter period, which did not significantly affect QM6A#4 levels. Throughout the experiment, QM6A#4 remained viable. These results indicate that, following release into the environment, live T. reesei will persist in soil for at least 2 seasons.Key words: competitive PCR, genetically engineered microorganisms (GEMs), genetically modified organism (GMO), survival of microorganisms, microcosm, Trichoderma.

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