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PubMed2005

Base cation stimulation of mycorrhization and photosynthesis of sugar maple on acid soils are coupled by foliar nutrient dynamics.

The nutritional benefits that mycorrhizal associations provide to plants may be constrained by acidic soil conditions resulting in decreased photosynthetic function. Sugar maple (Acer saccharum) and red maple (Acer rubrum) seedlings were grown on a native acidic (pH 4.1) soil both unamended and amended with base cations (pH 6.2). In a second study a fungicide treatment was included. Foliar nutrition, mycorrhizal colonization, photosynthesis and their relationships were assessed. On the native soil, red maple maintained higher levels of mycorrhizal colonization and photosynthesis than sugar maple but showed little response to base cation amendments. Mycorrhizal colonization and photosynthesis of sugar maple increased significantly in response to base cation amendments. Correlations were observed among mycorrhizal colonization, foliar nutrition and photosynthesis. The fungicide treatment indicated that 50% of the base cation-induced increase in sugar maple photosynthesis was mycorrhiza related. The results suggest that base cation stimulation of mycorrhization and photosynthesis of sugar maple on acid soils are coupled by foliar nutrient dynamics. Red maple exhibits much less sensitivity to these same edaphic conditions.

Acer↗
PubMed2005

[Energy characteristics of Casuarina equisetifolia ecosystem on coastal sand in Dongshan County, Fujian Province].

The study on the energy characteristics of Casurina equisetifolia community on red earth eolian sandy soil and homogeneous eolian sandy soil in Dongshan County of Fujian Province showed that the standing biomass and energy of Casurina equisetifolia community were 15 681.84 g x m(-2) and 317 795.31 kJ x m(-2) on red earth eolian sandy soil, and 5 129.87 g x m(-2) and 10 575.50 kJ x m(-2) on homogeneous eolian sandy soil, respectively. On homogeneous eolian sandy soil, the gross caloric value of the community ranged from 19.98 kJ x g(-1) to 21.39 kJ x g(-1), of which, dead branch was the highest while root was the lowest, and its percentage was 46.93% (truck) > 16.44%(root) > 13.92% (branch) > 12.28% (dead branch) > 5.87% (bark) > 3.90% (leaf) > 0.66% (fruit). The return amount of litter was 2061.77 kJ x m(-2) x yr(-1), and the net energy productivity was 12662.82 kJ x m(-2) x yr(-1). On red earth eolian sandy soil, the gross caloric value was 19.84 - 21.70 kJ x g(-1), among which, leaf was the highest while root was the lowest, and its percentage was 38.09% (truck) > 19.48% (branch) > 17.09% (root) > 16.86% (leaf) >6.83% (bark) > 0.88% (dead branch) > 0.77% (fruit). The returned amount of litter was 9070.47 kJ x m(-2) x yr(-1), and the net energy productivity was 31 298.70 kJ x m(-2) yr(-1). The standing biomass and energy of Casurina equisetifolia community were higher on red earth eolian sandy soil than on homogeneous eolian sandy soil, mainly because red earth eolian sandy soil had a thinner sandy layer (< 20 cm) and a stronger nutrient and water supplying ability.

Biomass↗
PubMed1980

Degradation of carboxin (Vitavax) and oxycarboxin (Plantvax) by Pseudomonas aeruginosa isolated from soil.

Pseudomonas aeruginosa capable of utilizing carboxin and oxycarboxin as sole sources of carbon and nitrogen was isolated from red sandy loam soil perfused with the solutions of these fungicides. The bacterium hydrolyzed oxycarboxin via the intermediate compound 2-(vinylsulphonyl) acetanilide liberating 2- (2-hydroxyethylsulphonyl) acetic acid and aminophenol, whereas carboxin was first oxidized to its sulphoxide and then to its sulphone before hydrolysis. Further hydrolysis of aminophenol by the organism resulted in the accumulation of ammonium which was partly oxidized to nitrite. Nitrite accumulated in the medium without further oxidation to nitrate.

Anilides↗
PubMed2000

Persistence of hexaconazole, a triazole fungicide in soils.

Persistence of hexaconazole (2-(2,4-dichlorophenyl)- 1-(1H-1,2,5-triazol-1-yl) hexan-2-ol) was studied in alluvial, red and black soils under flooded and nonflooded conditions. This fungicide was more persistent in all soils under flooded conditions than under nonflooded conditions and at 27 degrees C than at 35 degrees C. Degradation of hexaconazole in sterilized and nonsterilized soils proceeded at identical rates indicating a minor role of micro-organisms in its degradation. The soil persistence of hexaconazole was not affected by the addition of wheat straw both under flooded and nonflooded conditions.

Chromatography, Gas↗
PubMed2006

Mechanisms of microbially enhanced Fe acquisition in red clover (Trifolium pratense L.).

Soil microorganisms may play an important role in plant Fe uptake from soils with low Fe bioavailability, but there is little direct experimental evidence to date. We grew red clover, an Fe-efficient leguminous plant, in a calcareous soil to investigate the role of soil microbial activity in plant Fe uptake. Compared with plants grown in non-sterlie (NS) grown plants, growth and Fe content of the sterile(s) grown plants was significantly inhibited, but was improved by foliar application of Fe EDTA, indicating that soil microbial activity should play an important role in plant Fe acquisition. When soil solution was incubated with phenolic root exudates from Fe-deficient red clover, a few microbial species thrived while growth of the rest was inhibited, suggesting that the Fe-deficient (-Fe) root exudates selectively influenced the rhizosphere's microbial community. Eighty six per cent of the phenolic-tolerant microbes could produce siderophore [the Fe(III) chelator] under -Fe conditions, and 71% could secrete auxin-like compounds. Interestingly, the synthetic and microbial auxins (MAs) significantly enhanced the Ferric reduction system, suggesting that MAs, in addition to siderophores, are important to plant Fe uptake. Finally, plant growth and Fe uptake in sterilized soil were significantly increased by rhizobia inoculation. Root Fe-EDTA reductase activity in the -Fe plant was significantly enhanced by rhizobia infection, and the rhizobia could produce auxin but not siderophore under Fe-limiting conditions, suggesting that the contribution of nodulating rhizobia to plant Fe uptake can be at least partially attributed to stimulation of turbo reductase activity through nodule formation and auxin production in the rhizosphere. Based on these observations, we propose as a model that root exudates from -Fe plants selectively influence the rhizosphere microbial community, and the microbes in turn favour plant Fe acquisition by producing siderophores and auxins.

Indoleacetic Acids↗
PubMed2000

Acid mist and soil Ca and Al alter the mineral nutrition and physiology of red spruce.

We examined the effects and potential interactions of acid mist and soil solution Ca and Al treatments on foliar cation concentrations, membrane-associated Ca (mCa), ion leaching, growth, carbon exchange, and cold tolerance of red spruce (Picea rubens Sarg.) saplings. Soil solution Ca additions increased foliar Ca and Zn concentrations, and increased rates of respiration early in the growing season (July). Soil Al treatment had a broad impact, reducing foliar concentrations of Ca, Mg, Mn, P and Zn, and resulting in smaller stem diameters, sapling heights and shoot lengths compared with soil treatments with no added Al. Aluminum treatment also reduced respiration when shoots were elongating in July and decreased net photosynthesis at the end of the growing season (September). Three lines of evidence suggest that Al-induced alterations in growth and physiology were independent of foliar Ca status: (1) Ca concentrations in foliage of Al-treated saplings were within the range of sufficiency established for red spruce; (2) mCa concentrations were unaffected by Al treatment; and (3) no Al x Ca interactions were detected. Acid mist treatment increased foliar Fe and K concentrations and increased leaching of Ca, Mg, Mn, Zn, Fe, and Al from foliage. Leaching losses of Ca were more than twice those of the element with the next highest amount of leaching (Zn), and probably led to the reductions in mCa concentration and membrane stability of acid-treated saplings. Acidic mist resulted in enhanced shoot growth, and consistent reductions in foliar cold tolerance in the fall and winter. Of the few significant interactions among treatments, most involved the influence of mist pH and Al treatment on foliar nutrition. In general, reductions in cation concentration associated with Al addition were greater for pH 5.0-treated saplings than for pH 3.0-treated saplings. We propose that H(+)-induced leaching of mCa from mesophyll cells is the mechanism underlying acid-induced reductions in foliar cold tolerance of red spruce.

Journal Article↗
PubMed2000

Genetic diversity and biological control activity of novel species of closely related pseudomonads isolated from wheat field soils in South Australia.

Rhizobacteria closely related to two recently described species of pseudomonads, Pseudomonas brassicacearum and Pseudomonas thivervalensis, were isolated from two geographically distinct wheat field soils in South Australia. Isolation was undertaken by either selective plating or immunotrapping utilizing a polyclonal antibody raised against P. brassicacearum. A subset of 42 isolates were characterized by amplified 16S ribosomal DNA restriction analysis (ARDRA), BIOLOG analysis, and gas chromatography-fatty acid methyl ester (GC-FAME) analysis and separated into closely related phenetic groups. More than 75% of isolates tested by ARDRA were found to have >95% similarity to either Pseudomonas corrugata or P. brassicacearum-P. thivervalensis type strains, and all isolates had >90% similarity to either type strain. BIOLOG and GC-FAME clustering showed a >70% match to ARDRA profiles. Strains representing different ARDRA groups were tested in two soil types for biological control activity against the soilborne plant pathogen Gaeumannomyces graminis var. tritici, the causative agent of take-all of wheat and barley. Three isolates out of 11 significantly reduced take-all-induced root lesions on wheat plants grown in a red-brown earth soil. Only one strain, K208, was consistent in reducing disease symptoms in both the acidic red-brown earth and a calcareous sandy loam. Results from this study indicate that P. brassicacearum and P. thivervalensis are present in Australian soils and that a level of genetic diversity exists within these two novel species but that this diversity does not appear to be related to geographic distribution. The result of the glasshouse pot trial suggests that some isolates of these species may have potential as biological control agents for plant disease.

Bacterial Typing Techniques↗
PubMed2006

Pseudomonas fluorescens dynamics in the soil surface to subsurface transect.

Microbial displacement in the soil is an important process for bioremediation and dispersal of wastewater pathogens. We evaluated cell movement in surface and subsurface red-yellow podzolic soil driven by advection and microbial motility and also survival of a microbial population at high pressure as is prevalent in deep soil layers. Pseudomonas fluorescens Br 12, resistant to rifampycin and kanamycin, was used as a model organism traceable in non-sterile soil. Our results showed that more than 40% of the P. fluorescens population survived under high pressure, and that microbial motility was not a major factor for its displacement in the soil. Cells were adsorbed in similar amounts to surface and subsurface soils, but more viable cells were present in the leachate of surface than in subsurface soils. The nature of this unexpected cell binding to the subsurface soil was studied by EPR, Mossbauer, NMR, and infrared techniques, suggesting iron had a weak interaction with microbes in soil. P. fluorescens movement in soil resulted mainly from convection forces rather than microbial motility. The transport of this bacterium along the transept toward groundwater encountered restricted viability, although it survived under high pressure conditions simulating those in deep soil layers.

Biodegradation, Environmental↗
PubMed1992

Spectrofluorimetric determination of boron in soils, plants and natural waters with Alizarin Red S.

A simple and sensitive spectrofluorimetric method for the determination of boron with Alizarin Red S is described. The fluorescence intensity of the complex formed in aqueous solution develops immediately and heating is not required. The excitation and emission wavelengths are 465 and 615 nm, respectively. The detection limit is 7.2 ng cm-3. A study was made of the influence of several ions as potential interferents. The method was applied satisfactorily to the determination of boron in soils, plants and natural waters.

Anthraquinones↗
PubMed2004

The effect of sulfate-reducing bacteria on adsorption of 137Cs by soils from arid and tropical regions.

Soils from different climatic regions of Australia were studied to determine their adsorption of (137)Cs, and the effect of microbial sulfate reduction on this adsorption. The soils consisted of a surface and regolith samples from the site of a proposed low and intermediate level radioactive waste repository in arid South Australia, and two red earth loam soils from an experimental plot in the tropical Northern Territory. The process of bacterial sulfate reduction substantially decreased the adsorption of (137)Cs to the arid and tropical soils, although extended incubation resulted in greater adsorption to the regolith sample. This could have implications for the mobility of radionuclides entering these soil ecosystems.

Adsorption↗
PubMed2006

A special vegetation index for the weed detection in sensor based precision agriculture.

Many technologies in precision agriculture (PA) require image analysis and image- processing with weed and background differentiations. The detection of weeds on mulched cropland is one important image-processing task for sensor based precision herbicide applications. The article introduces a special vegetation index, the Difference Index with Red Threshold (DIRT), for the weed detection on mulched croplands. Experimental investigations in weed detection on mulched areas point out that the DIRT performs better than the Normalized Difference Vegetation Index (NDVI). The result of the evaluation with four different decision criteria indicate, that the new DIRT gives the highest reliability in weed/background differentiation on mulched areas. While using the same spectral bands (infrared and red) as the NDVI, the new DIRT is more suitable for weed detection than the other vegetation indices and requires only a small amount of additional calculation power. The new vegetation index DIRT was tested on mulched areas during automatic ratings with a special weed camera system. The test results compare the new DIRT and three other decision criteria: the difference between infrared and red intensity (Diff), the soil-adjusted quotient between infrared and red intensity (Quotient) and the NDVI. The decision criteria were compared with the definition of a worse case decision quality parameter Q, suitable for mulched croplands. Although this new index DIRT needs further testing, the index seems to be a good decision criterion for the weed detection on mulched areas and should also be useful for other image processing applications in precision agriculture. The weed detection hardware and the PC program for the weed image processing were developed with funds from the German Federal Ministry of Education and Research (BMBF).

Agriculture↗
PubMed2004

Photodegradation of bensulfuron-methyl on soil surface.

Photolysis of bensulfuron-methyl on soil surface was studied under sunlight and UV light. Seven photoproducts were isolated and characterised by spectroscopic methods. The major processes in the photolysis of bensulfuron-methyl in soil are cleavage of the sulfonylurea bridge, scission of the SO2NH bond and contraction of the sulfuronylurea bridge. The rates of photodegradation of bensulfuron-methyl on different soils followed first-order rate kinetics with half lives of 21.9, 28.4, 36.9, 59.2 and 47.2 h (UV) and 23.1, 27.5, 29.1, 38.9 and 33.8 days (sunlight) for vertisol, alluvial, alfisol, red and laterite soils, respectively. The differences in rates of photodegradation were dependent upon the soil texture and organic matter content.

Biodegradation, Environmental↗
PubMed1977

Microbial society and its activity in the soil.

In this study, with the help of the buried slide method, a qualitative observation of the microsociological association in the soil was assessed. Fungal mycelium cohabiting with bacterial forms, rods as well as cocci, individual colonies of Azotobacter-type cells, and certain algae of Hantzschia species were recorded in a central European typical garden soil. The use of CHOLODNY-STRUGGER combination method was helpful in ascertaining the decaying nature of a soil nematode and also fungal mycelium which, during the process of decomposition, served there as a substrate for bacterial multiplication. Colony of Clostridium-type rod-shaped bacteria existed between the soil particles, acting as living bridges. When examined under fluorescent microscope, the bacterial forms emitted shining fluorescence of green colour which in effect presented them as lighted objects, prominent against the dull red background of soil objects and other decaying substances.

Azotobacter↗
PubMed1984

Environmental factors in the etiology of endemic elephantiasis of the lower legs in tropical Africa.

The environmental factors including geography, geology and soil have been reviewed in areas of high prevalence of non-filariasis endemic elephantiasis surveyed in tropical Africa. These areas occur at altitudes above 1000 m where rainfall is seasonal and exceeds 1000 mm annually. The soil is a red clay, very slippery when wet and very adhesive if allowed to dry on the skin. These are also areas of past or present alkalic volcanism, the prevalence being highest in proximity to the volcanoes. The derived soils are notable for the high proportion of alumino-silicate particles of colloid size in the clays. The significance of these findings suggests that the number and small size of the clays. The significance of these findings suggests that the number and small size of the particles facilitates entry through the skin into the lymphatic tissues, where they exert the known irritant and fibrosing effects of silica and alumina.

Africa↗
PubMed2006

P and trace metal contents in biomaterials, soils, sediments and plants in colony of red-footed booby (Sula sula) in the Dongdao Island of South China Sea.

Concentrations of P and trace metals Zn, Cu, Cd, Pb and Hg in the faeces, bones, eggshells and feathers of seabirds and in the plants, soils and sediments with and without seabird influence on Dongdao Island, South China Sea, were determined and analyzed. Among the seabird biomaterials, the levels of P, Zn, Cu and Cd are the highest in the droppings and several times those in other materials; the Hg concentration is the highest in the feathers; and the Pb content is comparable among these biomaterials. These marked differences indicate different intake-bioaccumulation-elimination pathways for different trace metals. The levels of P, Zn, Cu, Cd and Hg in the plant, soil and sediment samples with the influence of seabird droppings are significantly higher than those in the samples without, and they are significantly correlated with each other. Thus, P, Zn, Cu, Cd and Hg are very likely to have a common source-predominantly bird guano-and the faeces of red-footed booby is an important vector for the flux of nutrient phosphorus and trace metals Zn, Cu, Cd and Hg from marine to island ecosystems on Dongdao Island.

Animal Structures↗
PubMed2006

Stable isotope geochemistry of calcrete nodules and septarian concretions in a Quaternary 'red clay' paleovertisol from Hungary.

Calcrete nodules and concretions in unusually large amounts are embedded in the Quaternary clay-rich (Vertisol-type) 'red clay' soil-sedimentary complex at the pediment of the Mátra Mountains (Hungary). Stable isotope signatures were studied in nodules and septarian concretions, uncommon due to their several millimeter sized calcite crystals filling voids and fractures, to reveal their origin. The isotope composition of calcrete covers a wide range: delta18O=-5.9 to-10.4 per thousand and delta13C=-8.9 to-12.3 per thousand (vs. V-PDB). Isotope compositions support pedogenic (sensu stricto) and/or shallow groundwater origin for the calcrete nodules and concretions, the role of 'evolved' (isotopically modified) groundwaters in the formation of secondary carbonate was possibly subordinate. Late-stage, large, Mn-rich euhedral calcite crystals in concretions have the lowest delta13C values, which are interpreted as a result of larger contribution of isotopically light organic carbon due to decomposition of organic matter under reducing conditions. Precipitation of late calcite crystals in concretions occurred in early diagenetic environment after shallow burial of the 'red clay' paleovertisol.

Aluminum Silicates↗
PubMed2004

Influence of packing media on nitrogen removal in a subsurface infiltration system.

Influence of packing media on nitrogen removal in a subsurface infiltration system was studied. System A was filled with loamy soil and system B was filled with mixed soil of 75% red clay with 25% cinder. Both systems were fed with sewage at the same hydraulic loading of 2 cm/d at continuous operation mode. The same excellent removal performances of COD and T-P could be achieved in both infiltration systems with removal rates about 85% and 98%, respectively. In system A, NH4+ -N removal rate was as high as 96.5% and T-N removal rate was relatively much lower as 55.7%. And in system B, NH4+ -N removal rate was as low as 75.4% and T-N removal rate was relatively much higher as 75.5% . The difference was attributed to different soil oxidation-reduction condition that was greatly influenced by soil texture in subsurface infiltration system. Loamy soil led to oxidative condition that was favorable to nitrification and disadvantageous to denitrification. The results were just adverse to the system filled with clay. Intermittent operation was adopted to improve nitrogen removal in system B. NH4+ -N removal rate could be increased to about 95% and T-N removal rate could be increased to about 90% at intermittent operation mode in system B. Analysis of nitrogen removal mechanisms indicated that nitrification-denitrification was the primary nitrogen removal path in subsurface infiltration system and crop uptake was another important nitrogen removal way. It was the key to improve the total N removal performance that a suitable packing soil was available to present favorable oxidation-reduction condition for simultaneous nitrification and denitrification.

Aluminum Silicates↗
PubMed1982

Studies on the selection of streptomycetes in the rhizoplane of sugar-cane.

The overwhelming majority of species of Streptomyces (S. aburaviensis, S. chromofuscus, S. collinus, S. tenebrarius, S. galilaeus, etc.) and Streptoverticillium aureoversales indigenous in the cultivated horizon of the red ferralitic tropical soil of an investigated sugar-cane plantation, were completely lacking in the root surface region of this plant. Only two species (S. griseorubiginosus and S. viridochromogenes) characterized by very broad C- and N-source utilization spectra, proved capable of colonizing the roots of sugar-cane under natural circumstances. They are not stable members of the rhizoplane but, in contrast to many other species of Streptomyces, are very successful occasional root colonizers. S. viridochromogenes occurred also in the root far soil region but S. griseorubiginosus could only be detected in the rhizoplane.

Ecology↗