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Made available in DSpace on 2021-06-25T12:33:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-10-01. Added 1 bitstream(s) on 2021-07-15T14:36:31Z : No. of bitstreams: 1 S0006-87052020000400623.pdf: 197868 bytes, checksum: 5c72253dabd8ac9ce3daf0820f203157 (MD5) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Oxisols are important soils that have been converted from native vegetation to croplands, and can affect soil biological properties such as microbial biomass and enzyme activity. Thus, the aim of this study was to evaluate the changes on soil microbial biomass and enzyme activity when native vegetation (NV) was converted to cropland (CL), such as maize or sugarcane in six oxisols from Sao Paulo state, Brazil. Soil microbial biomass C (MBC) and N (MBN), and the activity of arylsulphatase, dehydrogenase and fluorescein diacetate hydrolysis (FDA) were assessed in samples collected at 0-0.20 m. In general, MBC was higher under NV than CL (about + 40%), while MBN and FDA did not show a consistent pattern between NV and CL. All soils showed higher values of arylsulfatase (increased from 101 to 717%) and dehydrogenase (increased 15 to 220%) under NV than CL. In conclusion, soil microbial biomass C is usually higher under native vegetation than cropland. Arylsulphatase and dehydrogenase were the attributes that presented better differentiation between native and cropped soils. Univ Estadual Paulista, Fac Ciencias Agr & Vet, Dept Tecnol, Jaboticabal, SP, Brazil Univ Brasil, Programa Posgrad Prod Anim, Descalvado, SP, Brazil Univ Fed Piaui, Ctr Ciencias Agr, Dept Engn Agr & Solos, Teresina, PI, Brazil Univ Estadual Paulista, Fac Ciencias Agr & Vet, Dept Ciencias Exatas, Jaboticabal, SP, Brazil Univ Estadual Paulista, Fac Ciencias Agr & Vet, Dept Tecnol, Jaboticabal, SP, Brazil Univ Estadual Paulista, Fac Ciencias Agr & Vet, Dept Ciencias Exatas, Jaboticabal, SP, Brazil

Background Soil respiration (SR) is a critical process for understanding the impact of climatic conditions and land degradation on the carbon cycle in terrestrial ecosystems. We measured the SR and soil environmental factors over 1 year in four land uses with varying levels of disturbance and different vegetation types viz., mixed forest cover (MFC), Prosopis juliflora (Sw.) forest cover (PFC), agricultural field (AF), and vegetable field (VF), in a semi-arid area of Delhi, India. Our primary aim was to assess the effects of soil moisture (SM), soil temperature (ST), and soil microbial activity (SMA) on the SR. Methods The SR was measured monthly using an LI-6400 with an infrared gas analyser and a soil chamber. The SM was measured using the gravimetric method. The ST (10 cm) was measured with a probe attached to the LI-6400. The SMA was determined by fluorescein diacetate hydrolysis. Results The SR showed seasonal variations, with the mean annual SR ranging from 3.22 to 5.78 μmol m−2 s−1 and higher SR rates of ~ 15–55% in the cultivated fields (AF, VF) than in the forest sites (MFC, PFC). The VF had significantly higher SR (P < 0.05) than the other land uses (AF, PFC, MFC), which did not vary significantly from one another in SR (P < 0.05). The repeated measures ANOVA evaluated the significant differences (P < 0.05) in the SR for high precipitation months (July, August, September, February). The SM as a single factor showed a strong significant relationship in all the land uses (R2 = 0.67–0.91, P < 0.001). The effect of the ST on the SR was found to be weak and non-significant in the PFC, MFC, and AF (R2 = 0.14–0.31; P > 0.05). Contrasting results were observed in the VF, which showed high SR during summer (May; 11.21 μmol m−2 s−1) and a significant exponential relationship with the ST (R2 = 0.52; P < 0.05). The SR was positively related to the SMA (R2 = 0.44–0.5; P < 0.001). The interactive equations based on the independent variables SM, ST, and SMA explained 91–95% of the seasonal variation in SR with better model performance in the cultivated land use sites (AF, VF). Conclusion SM was the key determining factor of the SR in semi-arid ecosystems and explained ~ 90% of the variation. Precipitation increased SR by optimizing the SM and microbial activity. The SMA, along with the other soil factors SM and ST, improved the correlation with SR. Furthermore, the degraded land uses will be more susceptible to temporal variations in SR under changing climatic scenarios, which may influence the carbon balance of these ecosystems.

International audience; Two 915-MHz microwave treatments (2 kW-8 min and 4 kW-4 min) were applied to soil and their effects were monitored just after treatments (T0) and 26 days (T26) in soil microcosms. Densities of culturable bacteria, fluorescent pseudomonads and nematodes, hydrolysis activity and soil DNA content declined by over 50% immediately after both microwave treatments (T0), excluding the total fungal 18S rRNA (-13 or -17%) and bacterial 16S rRNA copies (non-significant). A rapid shift in bacterial community composition occurred from T0 towards a large increase in the relative abundance of Firmicutes (+1650%) and a concomitant decrease in various phyla (e.g. Acidobacteria, Actinobacteria, Bacteroidetes, Proteobacteria) from -85 to -61%. At T26 and for both treatments, fluorescein diacetate hydrolysis, density of culturable bacteria, 18S rRNA gene numbers, Simpson diversity, relative abundances of Bacteroidetes and Proteobacteria regained levels similar to controls. Alpha, Delta and Gamma classes Proteobacteria also end up reaching a similar level. In contrast, fluorescent pseudomonad density, nematode diversity and abundance, soil DNA content and relative abundances of some phylum (Acidobacteria, Actinobacteria, Chloroflexi) did not increase in such proportions. Most of the soil biological properties have not been permanently impacted. Nevertheless, the recovery kinetics highly differed according properties, with resilience indices at T26 varying from -87 to +99%.

Aim of study: This study evaluated the effect of the application of liquid aerobic treated manure (continuous liquid composting, CLC) on physical, chemical and biological soil properties, with the objective of monitoring changes induced by soil management with CLC as a biofertilizer.Area of study: Colonia, Uruguay (lat. 34,338164 S, long. 57,222630 W).Material and methods: Soil’s chemical properties, including nitrogen mineralization potential (NMP) and 15 microbiological properties (microbial biomass carbon, MBC; mesophylic aerobic bacteria; actinobacteria; filamentus fungi; fluorescein diacetate hydrolysis; dehydrogenase; with NMP; acid and alkaline phosphatase; cellulolose degraders; P-solubilizing bacteria; nitrifying; denitrifying and free-living N-fixing microorganisms; glomalin; and soil-pathogenicity index, SPI) were evaluated in two sites with similar cropping history, with one and three years of respective CLC application.Main results: CLC application had significant effects on soil microbial biomass (p

In this study, we investigated the effects of one-off applications of glyphosate, glufosinate, paraquat, and paraquat-diquat on soil microbial diversity and function. All herbicides were added to soil as pure compounds at recommended dose and were incubated under laboratory conditions for 60 days. High-throughput phylogenetic marker gene sequencing revealed that none of the herbicides significantly influenced the richness, evenness and composition of bacterial and archaeal communities. Likewise, the diversity, composition and size of nematode communities were not significantly influenced by any of the herbicides. From a functional perspective, herbicides did not significantly affect fluorescein diacetate hydrolysis (FDA) and beta-glucosidase activities. Furthermore, the ability of soil organisms to utilise 15 substrates was generally unaffected by herbicide application. The only exception to this was a temporary impairment in the ability of soil organisms to utilise three organic acids and an amino acid. Given the global and frequent use of these herbicides, it is important that future studies evaluate their potential impacts on microbial communities in a wider-range of soils and environmental conditions.

Agricultural drainage ditches are conduits between production acreage and receiving aquatic systems. Often overlooked for their mitigation capabilities, agricultural drainage ditches provide an important role for nutrient transformation via microbial metabolism. Variations in ecoenzyme activities have been used to elucidate microbial metabolism and resource demand of microbial communities to better understand the relationship between altered nutrient ratios and microbial activity in aquatic ecosystems. Two agricultural drainage ditches, one in the northeast portion of the Arkansas Delta and the other in the lower Mississippi Delta, were monitored for a year. Sediment samples were collected prior to each ditch being dredged (cleaned), and subsequent post-dredging samples occurred as soon as access was available. Seasonal samples were then collected throughout a year to examine effects of dredging on selected nutrient concentrations and ecoenzymatic activity recovery in drainage ditch sediments. Phosphorus concentrations in sediments after dredging decreased 33–66%, depending on ditch and phosphorus extraction methodology. Additionally, ecoenzymatic activity was significantly decreased in most sediment samples after dredging. Fluorescein diacetate hydrolysis activity, an estimate of total microbial activity, decreased 56–67% after dredging in one of the two ditches. Many sample sites also had significant phosphorus and ecoenzymatic activity differences between the post-dredge samples and the year-long follow-up samples. Results indicate microbial metabolism in dredged drainage ditches may take up to a year or more to recover to pre-dredged levels. Likewise, while sediment nutrient concentrations may be decreased through dredging and removal, runoff and erosion events over time tend to quickly replenish nutrient concentrations in replaced sediments. Understanding nutrient dynamics and microbial metabolism within agricultural drainage ditches is a crucial step toward addressing issues of nutrient enrichment in aquatic receiving systems, especially those contributing to the Gulf of Mexico.

We tested the over time effect of different selenium doses [50 (D50) and 100 (D100) g ha−1 of Se as Na2SeO3] on a soil under corn (Zea mays L.) cultivation. The soil was sampled 18 (t1), 48 (t2) and 59 (t3) days after the addition of Se and analysed for total Se, organic carbon and nitrogen, water-extractable organic carbon, available P, microbial biomass-C (Cmic) contents, the cumulative basal respiration (ΣCO2-C) and some enzymatic activities. Our findings showed Se fertilization increased the total soil Se content, although the differences between the treated and the untreated soils disappeared over time. Se fertilization had a negligible effect on the selected soil chemical and biochemical properties, with the exception of the ΣCO2-C, and fluorescein diacetate hydrolysis and dehydrogenase activity. Indeed, these parameters showed lower values at t3 in the treated than in the untreated soils without significant decrease of the Cmic suggesting a less energy demanded by the soil microorganisms for their own maintenance. This finding suggested a better adaptation of the microbial community to the modified conditions in the treated soils, where Se fertilization might have caused a shift in soil microbial community structure and/or promoted the survival of selected microorganisms. Overall, the obtained data highlighted that Se fertilization with Na-selenite, at the rate of 50 and 100 g ha−1, had no negative impact on soil chemical and biochemical parameters, at least on a short term.

Lead-polluted agricultural soils are a serious problem for food safety, with organic amendment being a promising mitigation method from the environmental perspective. Therefore, the purpose of this study was to evaluate lead availability and the effectiveness of the application of compost of biosolid with wood shavings and yard trimmings in contaminated soils. The physicochemical (Pb distribution, organic matter, pH, electric conductivity, cation exchange capacity, nitrogen, phosphorus, carbon, carbonates, exchangeable cations, sodium) and biological parameters (the microbial activity obtained by fluorescein diacetate hydrolysis) in Pb-polluted and non-polluted agricultural soils were evaluated after the addition of biosolid with wood shavings and yard trimming compost. Topsoils (lead-polluted and control) were collected in the vicinity of a former battery-recycling plant, amended with compost (0%, 5%, and 10%), and incubated in controlled conditions for 118 days. The results showed that lead availability decreased significantly, and the nutritional quality of the soils increased in the soils amended with 10% of compost. Taken together, the results of the present study indicated that compost amendment could be an effective method for mitigating the negative effects of lead in agricultural soils. Fil: Ferreyroa, Gisele Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Vergara Cid, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Verdenelli, Romina Aylen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Dominchin, Maria Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Meriles, José M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Pignata, Maria Luisa. Universidad Nacional de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Rodriguez, Judith Hebelen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina

Due to the increasing interest and the use of immobilized biocatalysts in bioremediation studies, there is a need for the development of an assay for quick and reliable measurements of their overall enzymatic activity. Fluorescein diacetate (FDA) hydrolysis is a widely used assay for measuring total enzymatic activity (TEA) in various environmental samples or in monoculture researches. However, standard FDA assays for TEA measurements in immobilized samples include performing an assay on cells detached from the carrier. This causes an error, because it is not possible to release all cells from the carrier without affecting their metabolic activity. In this study, we developed and optimized a procedure for TEA quantification in the whole biofilm formed on the carrier without disturbing it. The optimized method involves pre-incubation of immobilized carrier in phosphate buffer (pH 7.6) on the orbital shaker for 15 min, slow injection of FDA directly into the middle of the immobilized carrier, and incubation on the orbital shaker (130 rpm, 30 &deg, C) for 1 h. Biofilm dry mass was obtained by comparing the dried weight of the immobilized carrier with that of the unimmobilized carrier. The improved protocol provides a simple, quick, and more reliable quantification of TEA during the development of immobilized biocatalysts compared to the original method.

The present study evaluated the effect of nanochitosan in combination with plant growth promoting rhizobacteria (PGPR), PS2 and PS10 on maize growth. The PGPR were earlier recognized as Bacillus spp. on the basis of 16S rDNA sequencing. The observation revealed enhanced plant health parameters like seed germination (from 60 to 96.97%), plant height (1.5-fold increase), and leaf area (twofold). Variability in different physicochemical parameters (pH, oxidizable organic carbon, available phosphorous, available potassium, ammoniacal nitrogen and nitrate nitrogen) was observed. Activities of soil health indicator enzymes (dehydrogenase, fluorescein diacetate hydrolysis and alkaline phosphatase) were also enhanced 2 to 3 fold. Plant metabolites with respect to different treatments were also analyzed using gas chromatography–mass spectroscopy (GC–MS) and the result revealed an increase in the amounts of alcohols, acid ester and aldehyde compounds. Increase in organic acids indicates increased stress tolerance mechanism operating in maize plant after treatment of nanochitosan.

We investigated the catalytic activity of ZIF-8 in the fluorescein diacetate hydrolysis via super-resolution fluorescence microscopy. Acid-base activity is detected only on the outer surface and crystalline defects. Oleic acid etching introduces extra porosity and allows for catalytic conversions inside of the crystals, but leads to overall activity loss. ispartof: CrystEngComm vol:19 issue:29 pages:4162-4165 status: published

The nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) is widely used within agriculture to reduce nitrate leaching and improve nitrogen use efficiency of fertilizers, but few studies examined effects on non-target soil functions and microorganisms, i.e. other than the intended delay of ammonia oxidation. We investigated effects of DMPP amendment equivalent to 0 (Control), 1 (regular dose, RD) or 10 (high dose, HD) kg ha−1 in a sandy loam grassland soil at 50% water-filled pore space. Following incubation for 1, 7 or 14 d, soil was analyzed for fluorescein diacetate hydrolysis, dehydrogenase activity, phospholipid fatty acid composition and potential ammonia oxidation. DMPP showed no significant non-target effects (p > 0.05), but a possible stress response in HD was indicated by a factor analysis of phospholipid fatty acid composition. There was a strong DMPP inhibition on potential ammonia oxidation which was still significant (p < 0.05) in HD after 14 d. In separate treatments receiving 50 mg NH4 +-N kg−1 in addition to DMPP, the inhibition of nitrate accumulation was similar in RD and HD at around 75%. Abundances of the gene amoA from ammonia oxidizing bacteria (AOB) and archaea (AOA) were quantified, and cell-specific nitrification rates were estimated. There was a general trend of increasing AOA and AOB abundance towards the end of incubation irrespective of DMPP treatment, whereas cell-specific activity of AOA and/or AOB was reduced in the presence of DMPP. Overall, this study indicated that DMPP effectively inhibited nitrification activity without effects on ammonia oxidizer populations, as well as nontarget soil microorganisms or functions.

Integrated crop-livestock systems (ICLs) are a viable strategy for the recovery and maintenance of soil characteristics. In the present study, an ICL experiment was conducted by the Instituto Agronômico do Paraná in the municipality of Xambre, Parana (PR), Brazil, to evaluate the effects of various grazing intensities. The objective of the present study was to quantify the levels of microbial biomass carbon (MBC) and soil enzymatic activity in an ICL of soybean (summer) and Brachiaria ruziziensis (winter), with B. ruziziensis subjected to various grazing intensities. Treatments consisted of varying pasture heights and grazing intensities (GI): 10, 20, 30, and 40 cm (GI-10, GI-20, GI-30, and GI-40, respectively) and a no grazing (NG) control. The microbial characteristics analysed were MBC, microbial respiration (MR), metabolic quotient (qCO2), the activities of acid phosphatase, β-glucosidase, arylsuphatase, and cellulase, and fluorescein diacetate (FDA) hydrolysis. Following the second grazing cycle, the GI-20 treatment (20-cm - moderate) grazing intensity) contained the highest MBC concentrations and lowest qCO2 concentrations. Following the second soybean cycle, the treatment with the highest grazing intensity (GI-10) contained the lowest MBC concentration. Soil MBC concentrations in the pasture were favoured by the introduction of animals to the system. High grazing intensity (10-cm pasture height) during the pasture cycle may cause a decrease in soil MBC and have a negative effect on the microbial biomass during the succeeding crop. Of all the enzymes analyzed, only arylsuphatase and cellulase activities were altered by ICL management, with differences between the moderate grazing intensity (GI-20) and no grazing (NG) treatments. O sistema de integração lavoura-pecuária (ILP) tem se evidenciado como alternativa viável para a recuperação e manutenção das características do solo. Este estudo foi desenvolvido em um experimento de ILP conduzido pelo Instituto Agronômico do Paraná no município de Xambrê, PR, com diferentes intensidades de pastejo. O objetivo deste trabalho foi avaliar o carbono da biomassa microbiana (CBM) e a atividade enzimática no solo, em sistema de integração lavoura-pecuária com soja cultivada no verão e Brachiaria ruziziensis no inverno, sendo esta submetida a diferentes intensidades de pastejo. Os tratamentos constaram de diferentes alturas de pasto e intensidades de pastejo: 10; 20; 30; e 40 cm (IP-10, IP-20, IP-30 e IP-40, respectivamente) e uma área sem pastejo (SP). Os atributos microbiológicos analisados foram CBM, respiração microbiana (RM), quociente metabólico (qCO2), atividade das enzimas fosfatase ácida, β-glucosidase, arilsulfatase, celulase e hidrólise do diacetato de fluoresceína (FDA). Após o segundo ciclo da pastagem, o tratamento IP-20 (intensidade moderada de pastejo 20 cm) apresentou os maiores teores de CBM e os menores de qCO2. Após o segundo ciclo da soja, o tratamento com maior intensidade de pastejo IP-10 demonstrou o menor teor de CBM. Os teores de CBM do solo na pastagem foram favorecidos pela inserção dos animais no sistema. A alta intensidade de pastejo (10 cm de altura da pastagem) durante o ciclo da pastagem pode provocar redução no C microbiano do solo, com efeito negativo sobre a mesma na cultura sucessora. Entre as enzimas avaliadas, somente a arilsulfatase e celulase foram sensíveis para avaliar o manejo ILP, com diferenças entre os tratamentos com intensidade moderada de pastejo (IP-20) e a área sem pastejo.

A solarização é um método de desinfestação que consiste na cobertura do solo com um filme de polietileno transparente, durante o período de intensa radiação solar, e atua por meio do aumento da temperatura do solo. Quatro ensaios foram realizados no estado de São Paulo, nos municípios de Mogi das Cruzes, Jarinu, Piracicaba e Itatiba, nos anos de 2000 e 2001, com o objetivo de avaliar os efeitos da solarização nas propriedades físicas, químicas e biológicas dos solos. A solarização reduziu significativamente a resistência à penetração dos solos nos ensaios de Jarinu, Piracicaba e Itatiba. Em Jarinu, oito meses após a retirada do plástico, as diferenças entre os tratamentos permaneceram. Por outro lado, em Mogi das Cruzes, onde o ensaio foi instalado em solo turfoso, a solarização causou aumento na resistência na camada de 2,5 a 5 cm de profundidade. Nos ensaios de Piracicaba e Jarinu, foram feitas avaliações de macro, microporosidade, porosidade total e densidade, não tendo os tratamentos diferido entre si, porém houve uma tendência de redução na densidade dos solos solarizados. A atividade microbiana, avaliada pela hidrólise de diacetato de fluoresceína, foi reduzida pela solarização. A supressividade a Fusarium oxysporum f. sp. phaseoli foi avaliada in vitro, pela colonização de amostras de solo usando um isolado marcado com resistência a benomyl, no ensaio de Mogi das Cruzes. A solarização reduziu a recuperação do patógeno, evidenciando um aumento da supressividade. Nos solos solarizados, houve aumento significativo dos teores de N-NH4+ em todos os experimentos, Mn em três, N-NO3-, Mg2+ e saturação por bases em dois e K+ em um experimento. Ocorreu redução dos teores de Cu, Fe e H + Al em dois experimentos e Zn em um ensaio. Segundo os resultados, a solarização promoveu alterações nas propriedades físicas, químicas e biológicas dos solos, melhorando a estrutura, liberando nutrientes e aumentando a supressividade. Solarization is a method for soil disinfestation, taking effect by increased soil temperatures under soil covers of transparent polyethylene sheets during the period of intense solar irradiation. Four field experiments were set up in the state of São Paulo, Brazil (districts of Mogi das Cruzes, Jarinú, Piracicaba and Itatiba), in the years 2000 and 2001, to evaluate the effects of soil solarization on physical, chemical and biological soil properties. Solarization caused a significant reduction in penetration resistance of the evaluated soils in Jarinu, Piracicaba, and Itatiba. In Jarinu, measurements carried out eight months after the removal of the plastic sheet showed that the effect of solarization on penetration resistance was still similar to that observed in the first evaluation. However, in Mogi das Cruzes, in an organic soil, solarization increased the soil's penetration resistance in the 2.5-5.0 cm layer. Solarization did not affect the macro-, micro- and total porosity of soils in Piracicaba and Jarinu, where these properties were measured, however it did reduce the apparent density. In an evaluation by fluorescein diacetate hydrolysis, the microbial activity in the soil proved to decrease by solarization. In Mogi das Cruzes, the suppressiveness to Fusarium oxysporum f. sp. phaseoli was evaluated in vitro by colonizing soil samples with an isolate marked with benomyl resistance. Solarization reduced the recovery of the pathogen, indicating an increase in suppressiveness. In solarized plots, there was a significant increase in the concentration of NH4+-N in all experiments, of Mn in three, of NO3--N, Mg2+, and base saturation in two, and K+ in one experiment. On the other hand, the concentration of Cu, Fe, and H + Al decreased in two places, and Zn in one. Results showed that solarization caused changes in physical, chemical and biological soil properties, improving the soil structure, releasing nutrients, and increasing disease suppressiveness.

Soil fumigation with the synthetic essential oil of mustard (93% allyl isothiocyanate) (EOM) was evaluated as a substitute of bio-fumigation with cruciferous plant species, using Sclerotium rolfsii and Sclerotinia sclerotiorum as test pathogens, together with its non-target effect on the general population of soil microorganisms. The mortality of the sclerotia of both fungi was dependent upon the concentration of EOM and the exposure period. Exposure to the EOM vapors delayed in vitro germination of the sclerotia.Total germination of the control sclerotia of S. rolfsii, after 120 h incubation, was 94%, of which 88% germinated within 48 h. In contrast, to the total germination of 77% or 47%, less than 3% germinated in 48 h when exposed for 4 or 7 days to 50 µl EOM/L. Exposure to 100 µl/l for 4 or 7 days resulted in the mortality of 50 and 100% sclerotia, respectively. The tendency for delayed germination and mortality was similar for the sclerotia of S. sclerotiorum. No viable sclerotia of either fungus were detected to the depth of 10 cm in the air dried, moist or wet soil fumigated for 7 days with the EOM at the rate of 150 µl/L. In the field plots, no viable sclerotia of S. rolfsii were detected after 7-day exposure to the EOM applied to the upper soil layer at the rate of 9, 12, or 18 ml/m2 and covered with a plastic sheet, while 73, 50 and 15%, respectively, were recovered from uncovered plots. In field plots, the fluorescein diacetate hydrolysis decreased by EOM treatment. However, the colony forming units of actinomycetes and bacteria increased, but those of fungi decreased significantly. Soil fumigation with EOM can be used with several advantages, as a substitute of bio-fumigation with cruciferous plant species.

Araucaria angustifolia, commonly named Araucaria, is a Brazilian native species that is intensively exploited due to its timber quality. Therefore, Araucaria is on the list of species threatened by extinction. Despite the importance of soil for forest production, little is known about the soil properties of the highly fragmented Araucaria forests. This study was designed to investigate the use of chemical and biological properties as indicators of conservation and anthropogenic disturbance of Araucaria forests in different sampling periods. The research was carried out in two State parks of São Paulo: Parque Estadual Turístico do Alto do Ribeira and Parque Estadual de Campos de Jordão. The biochemical properties carbon and nitrogen in microbial biomass (MB-C and MB-N), basal respiration (BR), the metabolic quotient (qCO2) and the following enzyme activities: β-glucosidase, urease, and fluorescein diacetate hydrolysis (FDA) were evaluated. The sampling period (dry or rainy season) influenced the results of mainly MB-C, MB-N, BR, and qCO2. The chemical and biochemical properties, except K content, were sensitive indicators of differences in the conservation and anthropogenic disturbance stages of Araucaria forests. Although these forests differ in biochemical and chemical properties, they are efficient in energy use and conservation, which is shown by their low qCO2, suggesting an advanced stage of succession. Araucaria angustifolia, comumente chamada de araucária, é uma espécie nativa brasileira considerada a mais explorada devido à qualidade de sua madeira. Por isso, encontra-se na atualidade ameaçada de extinção. Apesar da importância do solo na produção florestal, pouco se conhece sobre as propriedades edáficas das florestas de araucária, as quais estão altamente fragmentadas. O presente trabalho teve como objetivo investigar a utilização de propriedades químicas e bioquímicas do solo como indicadores de conservação e interferência antrópica em florestas de araucária, em diferentes períodos de amostragem. A pesquisa foi realizada em dois parques no Estado de São Paulo: Parque Estadual Turístico do Alto do Ribeira e Parque Estadual de Campos do Jordão. As propriedades bioquímicas do solo avaliadas foram: carbono e nitrogênio da biomassa microbiana (C-BM e N-BM), respiração basal (RB), quociente metabólico (qCO2.) e atividade das enzimas b-glicosidase, urease e hidrólise do diacetato de fluoresceína (FDA). A época de amostragem (estação seca/chuvosa) influenciou os valores encontrados, principalmente nas propriedades C-BM, N-BM, RB e qCO2. As propriedades químicas e bioquímicas do solo avaliados, com exceção da variável K, foram indicadores sensíveis para detectar diferenças nos estádios de conservação e interferência antrópica das florestas de araucária. Embora diferentes com relação às propriedades químicas e biológicas do solo, as florestas envolvidas neste estudo foram eficientes no uso e na conservação da energia, já que apresentaram baixo qCO2, sugerindo que elas se encontram em estádio mais avançado de sucessão.

The Mississippi Delta Management Systems Evaluation Area (MSEA) project was designed to assess the effects of land management practices on water quality in three small oxbow lake watersheds; Thighman (1338. ha, 16. ha lake); Beasley (915. ha, 25. ha lake); and Deep Hollow (132. ha, 8. ha lake). Monthly water samples were monitored for enzymatic activity (fluorescein diacetate hydrolysis, alkaline phosphatase, and substrate utilization), chemical and physical analysis (suspended solids, dissolved organic carbon, pH, nitrate, ammonium, orthophosphate, and electrical conductivity), phytoplankton and bacterioplankton populations. All of these parameters were influenced by the intrinsic nature of the watersheds, with some parameters shifting as management changes were imposed on the surrounding agricultural fields. Thighman lake water typically maintained the highest suspended solid levels, dissolved organic carbon, algal and bacterial populations, enzyme activities, and heterotrophic metabolic indexes. Introduction of reduced tillage practices and glyphosate-resistant crops in Beasley watershed resulted in lower levels of suspended sediments, but had minimal impact on overall ranking of biochemical or microbiological properties. Likewise, conversion of Deep Hollow watershed from reduced tillage to conventional tillage had little effect on suspended sediment, and most microbial activity parameters remained intermediate. However, canonical analysis indicated dynamic changes in the microbial community, suggesting that biological parameters of lake water quality were affected by changes in crop and soil management practices. © 2010 .

Band-steaming of arable soil at 80-90 degrees C kill off weed seeds prior to crop establishment which allows an extensive intra-row weed control. Here we evaluated the side-effects of in situ band-steaming on soil respiration, enzyme activities, and numbers of culturable bacteria and fungi in an organic field soil. The results showed that mechanical disturbance created by band-steaming could be neglected as a mediator of microbial changes. Also, soil pH and water content was unaffected by band-steaming. Effects of band-steaming on in situ soil respiration and basal respiration, respectively, were insignificant or slightly stimulatory (P < 0.05). Fluorescein diacetate hydrolysis and arylsulfatase activity were significantly (P < 0.001) inhibited by 25 and 38%, respectively, and only showed weak recovery during 90 days after band-steaming. Bacterial colony-forming units increased after soil steaming whereas the number of fungal propagules was reduced by 50% (P < 0.001). This reduction persisted at a level of 38% after 90 clays (P< 0.001). Evaluated in relation natural environmental stresses, band-steaming showed ecologically tolerable short-term effects, but with weaker recovery potential and therefore possible long-term effects. However, band-steaming affects only a minor volume of the plough layer (

Sludge from kraft mill wastewater treatment was applied on two soils derived from volcanic ashes and, the effect on biological parameters of the soils was evaluated. The soils used in this study were an Andisol belonging of Gorbea Series and an Ultisol belonging of Collipulli Series. The sludge was added at rates of 0, 10, 20, 30 and 50 t ha -1 . Previously, germination of red clover (Trifolium pratense), white clover (Trifolium repens), alfalfa (Medicago sativa) and ryegrass (Lolium perenne) was tested to assess phytotoxicity of the sludge. The different soil-sludge mixtures were incubated at controlled temperature for 60 days and microbial respiration, microbial biomass carbon, fluorescein diacetate hydrolysis and acid phosphatase activity were evaluated throughout the incubation time. All biological parameters evaluated were sensitive enough to shown the effect of sewage sludge application on soil microorganisms. The sludge application at different rates increased significantly (P

The hydrolysis of the fluorescein diacetate (FDA), related to several soil hydrolases, has been utilised to estimate the potential microbial activity of soil freshly amended with a wide range of organic amendments and compared to the size and activity of soil microflora, measured by the microbial biomass C (B C) and CO2 evolution, respectively. Three different composting mixtures at different phases of the composting process were added to a semi-arid soil and incubated for 2 months under laboratory conditions. The addition of the organic amendment immediately increased B C and both measures of microbial activity (FDA and CO2 evolution). Highly significant correlations were found between FDA hydrolysis and B C for soil amended with the three composting mixtures (r = 0.81–0.96; P, This research was supported by a grant from the Italian Ministry for Agricultural, Food and Forestry Policies (MiPAAF), Finalized Project PANDA and the research project Ref. CTM2005-05324 financed by the Spanish Comisión Interministerial de Ciencia y Tecnología (CICYT).

Crop management may modify soil characteristics, and as a consequence, alter incidence of diseases caused by soilborne pathogens. This study evaluated the suppressiveness to R. solani in 59 soil samples from a microbasin. Soil sampling areas included undisturbed forest, pasture and fallow ground areas, annual crops, perennial crops, and ploughed soil. The soil samples were characterized according to abiotic variables (pH; electrical conductivity; organic matter content; N total; P; K; Ca; Mg; Al; H; S; Na; Fe; Mn; Cu; Zn; B; cation exchange capacity; sum of bases and base saturation) and biotic variables (total microbial activity evaluated by the CO2 evolution and fluorescein diacetate hydrolysis; culturable bacterial, fungal, actinomycetes, protozoa, fluorescent Pseudomonas and Fusarium spp. communities). The contribution and relationships of these variables to suppression to R. solani were assessed by path analysis. When all samples were analyzed together, only abiotic variables correlated with suppression of R. solani, but the entire set of variables explained only 51% of the total variation. However, when samples were grouped and analyzed by vegetation cover, the set of evaluated variables in all cases accounted for more than 90% of the variation in suppression of the pathogen. In highly suppressive soils of forest and pasture/fallow ground areas, several abiotic variables and fluorescein diacetate hydrolysis correlated with suppression of R. solani and the set of variables explained more than 98% of suppressiveness. As atividades agrícolas podem modificar as características do solo e, como conseqüência, alterar a incidência de patógenos veiculados pelo solo. Este trabalho avaliou a supressividade a R. solani em 59 amostras de solos de uma microbacia. As áreas amostradas foram selecionadas quanto à vegetação, incluindo mata, pasto/pousio, culturas anuais, culturas perenes e solo arado. As amostras de solo foram caracterizadas quanto às propriedades abióticas (pH, condutividade elétrica, teor de matéria orgânica, N total, P, K, Ca, Mg, Al, H, S, Na, Fe, Mn, Cu, Zn, B, capacidade de troca catiônica, soma de bases e saturação de bases) e bióticas (atividade microbiana do solo, avaliada pelo desprendimento de CO2 e hidrólise de diacetato de fluoresceína; comunidades de bactérias, fungos, actinomicetos, protozoários, Pseudomonas fluorescentes e Fusarium spp.). A contribuição e relação dessas variáveis para a supressividade a R. solani foram quantificadas por análise de coeficientes de trilha. Quando se avaliaram todas as amostras em conjunto, somente variáveis abióticas apresentaram correlação com a supressão a R. solani, mas o conjunto das variáveis explicou somente 51% da variação total. Entretanto, quando as amostras foram agrupadas e analisadas considerando o tipo de cobertura vegetal, o conjunto de variáveis explicou mais de 90% da variação da supressividade. Para as áreas de floresta e pasto/pousio, as quais foram classificadas como as mais supressivas, algumas variáveis abióticas e a hidrólise de diacetato de fluoresceína apresentaram correlação com a supressão de R. solani e o conjunto de variáveis explicou mais de 98% da supressividade nesses solos.

Because soil biota is influenced by a number of factors, including land use and management techniques, changing management practices could have significant effects on the soil microbial properties and processes. An experiment was conducted to investigate differences in soil microbiological properties caused by long- and short-term management practices. Intact monolith lysimeters (0.2 m2 surface area) were taken from two sites of the same soil type that had been under long-term organic or conventional crop management and were then subjected to the same 2.5-year crop rotation [winter barley (Hordeum vulgare L.), maize (Zea mais L.), lupin (Lupinus angustifolius L.), and rape (Brassica napus L. ssp. oleifera)] and two fertilizer regimes (following common organic and conventional practices). Soil samples were taken after crop harvest and analyzed for microbial biomass C and N, microbial activity (fluorescein diacetate hydrolysis, arginine deaminase activity, and dehydrogenase activity), and total C and N. The incorporation of the green manure stimulated growth and activity of the microbial communities in soils of both management histories. Soil microbial properties did not show any differences between organically and conventionally fertilized soils, indicating that crop rotation and plant type had a larger influence on the microbial biomass and enzyme activities than fertilization. Initial differences in microbial biomass declined, while the effects of farm management history were still evident in enzyme activities and total C and N. Links between enzyme activities and microbial biomass C varied depending on treatment, indicating differences in microbial community composition.

Biodegradation of petroleum hydrocarbons in cold environments, including Alpine soils, is a result of indigenous cold-adapted microorganisms able to degrade these contaminants. In the present study, the prevalence of seven genotypes involved in the degradation of n -alkanes ( Pseudomonas putida GPo1 alkB ; Acinetobacter spp. alkM ; Rhodococcus spp. alkB1 , and Rhodococcus spp. alkB2 ), aromatic hydrocarbons ( P. putida xylE ), and polycyclic aromatic hydrocarbons ( P. putida ndoB and Mycobacterium sp. strain PYR-1 nidA ) was determined in 12 oil-contaminated (428 to 30,644 mg of total petroleum hydrocarbons [TPH]/kg of soil) and 8 pristine Alpine soils from Tyrol (Austria) by PCR hybridization analyses of total soil community DNA, using oligonucleotide primers and DNA probes specific for each genotype. The soils investigated were also analyzed for various physical, chemical, and microbiological parameters, and statistical correlations between all parameters were determined. Genotypes containing genes from gram-negative bacteria ( P. putida alkB , xylE , and ndoB and Acinetobacter alkM ) were detected to a significantly higher percentage in the contaminated (50 to 75%) than in the pristine (0 to 12.5%) soils, indicating that these organisms had been enriched in soils following contamination. There was a highly significant positive correlation ( P < 0.001) between the level of contamination and the number of genotypes containing genes from P. putida and Acinetobacter sp. but no significant correlation between the TPH content and the number of genotypes containing genes from gram-positive bacteria ( Rhodococcus alkB1 and alkB2 and Mycobacterium nidA ). These genotypes were detected at a high frequency in both contaminated (41.7 to 75%) and pristine (37.5 to 50%) soils, indicating that they are already present in substantial numbers before a contamination event. No correlation was found between the prevalence of hydrocarbon-degradative genotypes and biological activities (respiration, fluorescein diacetate hydrolysis, lipase activity) or numbers of culturable hydrocarbon-degrading soil microorganisms; there also was no correlation between the numbers of hydrocarbon degraders and the contamination level. The measured biological activities showed significant positive correlation with each other, with the organic matter content, and partially with the TPH content and a significant negative correlation with the soil dry-mass content ( P < 0.05 to 0.001).

6 pages, 3 figures, 2 tables., The flocculated solid fraction of olive mill wastewaters, obtained from two different olive oil extraction systems (FOMW1 and FOMW2) was composted, with olive leaves (OL) as bulking agent, by the static pile system (Rutgers). The dynamic of organic matter (OM) degradation during composting and its relationship with the basal respiration and fluorescein diacetate (FDA) hydrolytic activity, as indicators of biological activity, were studied. Two mixtures were prepared: C1, from 65% FOMW1 plus 35% OL; and C2, from 74% FOMW2 plus 25% OL and 1% urea. The biooxidative phase of composting in C1, which had a high initial C/N ratio, was long, leading to a high OM degradation, mainly of the lignocellulosic compounds. The water-soluble organic carbon content, C/N ratio and the urea supplied as a N source for the C2 compost make this mixture more adequate for composting, as it had a shorter composting time than C1, and developed a microbial population with a high metabolic activity. The results for basal respiration in C1 and C2 were correlated at a high probability level with those of FDA hydrolysis, and both parameters can be used for establishing the degree of biological stability of the composting material., This research was financed by the Spanish CICYT through the PETRI project no. 95-0234-OP-02-02.

International audience; Fluorescein diacetate (FDA) hydrolysis has mainly been used, in soil studies, for measurement of microbial activity and/or for enumeration of bacteria. A protocol is proposed to apply the method to sewage treatment plant activated sludge. The results are compared with values of ETS (electron transport system) activity and oxygen consumption. Unlike ETS activity, FDA hydrolysis is not expected to be proportional to O2 consumption. However, its application to aquatic systems is simpler, less expensive and give results with better reproducibility. FDA hydrolysis may thus allow study of biological activity in situations where extensive surveys in time and/or space are needed.

Artificial soil sealing in urban areas has attracted increasing attention because of its potential hazard to urban ecosystem. Covering soils with impervious materials has a significant impact on their properties and is essentially an irreversible process. In contrast to natural, open soils, sealed soils undergo a significant alteration of their physicochemical properties, and in turn, negatively influence microbial biomass and enzymatic activity. In general, 33 soils from different parts of the city of Torun (NW Poland) were sampled and divided into 3 groups according to the degree of soil sealing: (1) soils sealed with semi-pervious concrete paving slabs (A), (2) soils sealed with impervious surfaces, such as asphalt and concrete (B), and (3) non-sealed soils (the reference group—C). Soil samples were assayed for (1) microbial biomass carbon (MBC), and nitrogen (MBN) and soil respiration activity (RESP), (2) the activity of soil enzymes, and (3) physicochemical properties. Soil sealing significantly reduced the content of carbon and nitrogen (both total and microbial), soil respiration, the activity of urease, and fluorescein diacetate hydrolysis compared to non-sealed soils (C), while the degree of soil sealing did not significantly affect these properties. Soil moisture and nitrate reductase activity were the only properties significantly differentiated by the degree of soil sealing. Canonical correlation analysis indicated that soil biological activity was caused mainly by the variation in MBC and MBN content, as well as dehydrogenase, catalase, and cellulase activities. The highest correlation was obtained between the soil moisture and the first canonical variable for microbial biomass and enzymatic activity. The results showed that the artificial sealing in urban areas can significantly alter the soils by reducing their carbon and nitrogen content as well as microbial biomass and its activity compared with open soils. The analysis of variance showed that the degree of soil sealing did not affect most of the studied soil properties, although the differences in raw data between impervious and semi-pervious sites were remarkable.

Spectrophotometric determination of the hydrolysis of fluorescein diacetate (FDA) was shown to be a simple, sensitive, and rapid method for determining microbial activity in soil and litter. FDA hydrolysis was studied in soil and straw incubated for up to 3 h. Hydrolysis was found to increase linearly with soil addition. FDA hydrolysis by pure cultures of Fusarium culmorum increased linearly with mycelium addition both in shake cultures and after inoculation into sterile soil. FDA hydrolysis by Pseudomonas denitrificans increased linearly with biomass addition. The FDA hydrolytic activities in soil samples from different layers of an agricultural soil were correlated with respiration. Acetone was found to be suitable for terminating the reaction.

Mining activities generally affect soil quality, degrading it and creating the need for consistent environmental recovery efforts. This study evaluates the influence of monospecific and mixed stands of Sesbania virgata (S) and Eucalyptus camaldulensis (E) on the chemical properties and microbial activity of the soil in a degraded area by clay extraction in the northern part of the state of Rio de Janeiro, Brazil. Four treatments (100S:100 % Sesbania , 100E: 00 % Eucalyptus , 50S:50E: 50 % Sesbania + 50 % Eucalyptus , and DASV: a degraded area with spontaneous vegetation) were established according to a randomized complete block design with three replicates. Samples were collected in the 0.00-0.10 m layer in the rainy season (March) and the dry season (September). The properties evaluated were pH in water; contents of P, K + , Ca 2+ , Mg 2+ , Al 3+ , H+Al, N, and C; C/N ratio; total microbial activity (soil respiration - CO 2 emission); and total enzymatic activity (fluorescein diacetate hydrolysis). The reforestation of degraded areas by clay mining with the species S. virgata and E. camaldulensis either in monospecific or mixed stands increased the nutrient contents, C levels, and total microbial activity in the soil. It was possible to separate the planting systems (100S, 100E, 50S:50E) and the DASV using principal component analysis. In both seasons, soil C contents, chemical properties, and biological variables improved in the planted areas, in contrast with the DASV. The revegetation of degraded areas by mining improved the chemical and biological properties of the soil, leading to higher soil quality in revegetated areas compared to degraded areas with natural vegetation.