Life Sciences Commons^™

Soil Net Nitrogen Mineralisation Across Global Grasslands, A. C. Risch, S. Zimmerman, R. Ochoa-Hueso, M. Schütz, B. Frey, J. L. Firn, P. A. Fay, F. Hagedorn, E. T. Borer, E. W. Seabloom, W. S. Harpole, J. M. H. Knops, Rebecca L. Mcculley, A. A. D. Broadbent, C. J. Stevens, M. L. Silveria, P. B. Adler, S. Báez, L. A. Biederman, J. M. Blair

Plant and Soil Sciences Faculty Publications

Soil nitrogen mineralisation (N_min), the conversion of organic into inorganic N, is important for productivity and nutrient cycling. The balance between mineralisation and immobilisation (net N_min) varies with soil properties and climate. However, because most global-scale assessments of net N_min are laboratory-based, its regulation under field-conditions and implications for real-world soil functioning remain uncertain. Here, we explore the drivers of realised (field) and potential (laboratory) soil net N_min across 30 grasslands worldwide. We find that realised N_min is largely explained by temperature of the wettest quarter, microbial biomass, clay content and bulk density. …

A Response Regulator From A Soil Metagenome Enhances Resistance To The Β-Lactam Antibiotic Carbenicillin In Escherichia Coli, Heather K. Allen, Ran An, Jo Handelsman, Luke A. Moe

Plant and Soil Sciences Faculty Publications

Functional metagenomic analysis of soil metagenomes is a method for uncovering as-yet unidentified mechanisms for antibiotic resistance. Here we report an unconventional mode by which a response regulator derived from a soil metagenome confers resistance to the β-lactam antibiotic carbenicillin in Escherichia coli. A recombinant clone (βlr16) harboring a 5,169 bp DNA insert was selected from a metagenomic library previously constructed from a remote Alaskan soil. The βlr16 clone conferred specific resistance to carbenicillin, with limited increases in resistance to other tested antibiotics, including other β-lactams (penicillins and cephalosporins), rifampin, ciprofloxacin, erythromycin, chloramphenicol, nalidixic acid, fusidic acid, and gentamicin. Resistance …

Fragipan Horizon Fragmentation In Slaking Experiments With Amendment Materials And Ryegrass Root Tissue Extracts, Anastasios D. Karathanasis, Lloyd W. Murdock, Christopher J. Matocha, John H. Grove, Yvonne L. Thompson

Plant and Soil Sciences Faculty Publications

Slaking experiments were conducted of fragipan clods immersed in solutions of poultry manure, aerobically digested biosolid waste (ADB), fluidized bed combustion byproduct (FBC), D-H₂O, CaCO₃, NaF, Na-hexa-metaphosphate, and ryegrass root biomass. The fragipan clods were sampled from the Btx horizon of an Oxyaquic Fragiudalf in Kentucky. Wet sieving aggregate analysis showed significantly better fragmentation in the NaF, Na-hexa-metaphosphate, and ryegrass root solutions with a mean weight diameter range of 15.5-18.8 mm compared to the 44.2-47.9 mm of the poultry manure, ADB, and FBC treatments. Dissolved Si, Al, Fe, and Mn levels released in solution were ambiguous. …

Induced Transcriptional Profiling Of Phenylpropanoid Pathway Genes Increased Flavonoid And Lignin Content In Arabidopsis Leaves In Response To Microbial Products, Mohammad Babar Ali, David H. Mcnear

Plant and Soil Sciences Faculty Publications

BACKGROUND: The production and use of biologically derived soil additives is one of the fastest growing sectors of the fertilizer industry. These products have been shown to improve crop yields while at the same time reducing fertilizer inputs to and nutrient loss from cropland. The mechanisms driving the changes in primary productivity and soil processes are poorly understood and little is known about changes in secondary productivity associated with the use of microbial products. Here we investigate secondary metabolic responses to a biologically derived soil additive by monitoring changes in the phenlypropanoid (PP) pathway in Arabidopsis thaliana.

RESULTS: This study …

In Situ Generated Colloid Transport Of Cu And Zn In Reclaimed Mine Soil Profiles Associated With Biosolids Application, Jarrod O. Miller, Anastasios D. Karathanasis, Christopher J. Matocha

Plant and Soil Sciences Faculty Publications

Areas reclaimed for agricultural uses following coal mining often receive biosolids applications to increase organic matter and fertility. Transport of heavy metals within these soils may be enhanced by the additional presence of biosolids colloids. Intact monoliths from reclaimed and undisturbed soils in Virginia and Kentucky were leached to observe Cu and Zn mobility with and without biosolids application. Transport of Cu and Zn was observed in both solution and colloid associated phases in reclaimed and undisturbed forest soils, where the presence of unweathered spoil material and biosolids amendments contributed to higher metal release in solution fractions. Up to 81% …

Soil Microbial Community Response To Hexavalent Chromium In Planted And Unplanted Soil, Ioannis Ipsilantis, Mark S. Coyne

Plant and Soil Sciences Faculty Publications

Theories suggest that rapid microbial growth rates lead to quicker development of metal resistance. We tested these theories by adding hexavalent chromium [Cr(VI)] to soil, sowing Indian mustard (Brassica juncea), and comparing rhizosphere and bulk soil microbial community responses. Four weeks after the initial Cr(VI) application we measured Cr concentration, microbial biomass by fumigation extraction and soil extract ATP, tolerance to Cr and growth rates with tritiated thymidine incorporation, and performed community substrate use analysis with BIOLOG GN plates. Exchangeable Cr(VI) levels were very low, and therefore we assumed the Cr(VI) impact was transient. Microbial biomass was reduced …

Effects Of Commercial Diazinon And Imidacloprid On Microbial Urease Activity In Soil And Sod, C. W. Ingram, Mark S. Coyne, David W. Williams

Plant and Soil Sciences Faculty Publications

Diazinon [O,O-diethyl O-2-isopropyl-6-methyl(pyrimidine-4-yl) phosphorothioate] and imidacloprid [1-(1-[6-chloro-3-pyridinyl]methyl)-N-nitro-2-imidazolidinimine] are applied to lawns for insect control simultaneously with nitrogenous fertilizers such as urea, but their potential effect on urease activity and nitrogen availability in turfgrass management has not been evaluated. Urease activity in enzyme assays, washed cell assays, and soil slurries was examined as a function of insecticide concentration. Intact cores from field sites were used to assess the effect of insecticide application on urease activity in creeping bentgrass (Agrostis palustris Huds.) and bluegrass (Poa pratensis L.) sod. Bacterial urease fromBacillus pasteurii and plant …

Nitrous Oxide Loss From Poultry Manure-Amended Soil After Rain, Mark S. Coyne, A. Villalba, Robert L. Blevins

Plant and Soil Sciences Faculty Publications

Land application of poultry wastes in Kentucky will increase as the broiler industry grows. If poultry manure stimulates N₂O loss from soil it will reduce the fertilizer N value of this waste. In contrast, stimulated N₂O loss in grass filter strips receiving the runoff from manured fields could help reduce contamination of surface water by NO⁻₃. Our objectives were to determine (i) if poultry manure stimulated N₂O loss in soil after rainfall and (ii) if there was an edge-of-field effect on N₂O loss in grass filters intercepting runoff from …