La quema del tamo de arroz a campo abierto es una de las mayores fuentes de contaminacion agricola, es por esto que el retorno de los residuos vegetales al suelo ha sido propuesto como una alternativa de manejo eficiente de los residuos pos-cosecha. Sin embargo, es poco conocido el impacto que tiene sobre los microorganismos edaficos involucrados en la disponibilidad y ciclaje de nutrientes. Por lo anterior, se planteo un experimento en campo para evaluar los cambios generados sobre la comunidad microbiana vinculada al ciclo del nitrogeno por la aplicacion de 4 tratamientos diferentes de manejo del tamo de arroz: (Cob+mo) cobertura del terreno con tamo de arroz inoculado con un consorcio microbiano de degradacion, (Inc+mo) tamo de arroz inoculado con el consorcio microbiano e incorporado, (Quema) quema del tamo y (Cob) cobertura del terreno con tamo de arroz sin inocular. Se realizaron 4 muestreos de suelo de soporte y suelo rizosferico antes y durante el ciclo de cultivo. Se evaluo la diversidad, estructura y composicion de la comunidad bacteriana a traves del analisis del gen 16S rRNA y se determino la actividad de las enzimas nitrogenasa, proteasa y ureasa vinculadas con el ingreso de nitrogeno al sistema edafico. Al final del ciclo de cultivo, los mapas de calor basados en la composicion y abundancia de especies, mostraron que las comunidades microbianas de los tratamientos alternos a la quema son mas similares entre si, indicando que la adicion de materia organica influencia la comunidad edafica microbiana. La actividad de las enzimas proteasa y ureasa se vio afectada por la aplicacion del consorcio de degradacion y la forma de retorno del tamo de arroz al suelo respectivamente. 
 
 
Palabras clave: (Incorporacion, cobertura, tamo de arroz, actividad enzimatica, 16S rRNA).

Evaluación de la diversidad taxonómica y funcional de la comunidad microbiana relacionada con el ciclo del nitrógeno en suelos de cultivo de arroz con diferentes manejos del tamo

Status of the World’s Soil Resources Main report

Lindane is a highly chlorinated and recalcitrant insecticide, capable to accumulate in soil and groundwater. Despite lindane has been banned in many countries, numerous sites still remain contaminated. The present work studies the bioremediation of soils of different textures contaminated with lindane by bioaugmentation with a quadruple Streptomyces consortium. In the three evaluated soils, silty loam soil (SLS), sandy soil (SS), and clayey soil (CS), heterotrophic microbial populations increased during the 14 days of the assay and CFU counts were higher in bioaugmented than in non-bioaugmented soils. Lindane removal was detected in all contaminated treatments, with higher removal percentages in the bioaugmented microcosms (SS 70.3%, SLS 36.3%, and CS 30.7%), than in non-bioaugmented ones (SS 40.4%, SLS 9.3%, and CS 12.2%). The pesticide half-life decreased by 77.3, 50.3, and 10.7 days, in bioaugmented SLS, CS, and SS, respectively. Lindane had an inhibitory effect on soil enzyme activities such as dehydrogenase, fluorescein diacetate hydrolysis, acid and alkaline phosphatases and increased the catalase activity, in non-bioaugmented controls; however, no effect on urease activity was observed. Bioaugmentation of soil microcosms with actinobacteria increased all enzymatic activities. Finally, the survival of the four strains of the consortium was demonstrated at the end of the bioremediation assay. Bioremediation using the Streptomyces sp. A2-A5-A11-M7 consortium represents a promising tool to restore different types of soils contaminated with organochlorine pesticides.

Lindane Bioremediation in Soils of Different Textural Classes by an Actinobacteria Consortium

Microorganisms are only effective when adequate conditions for their survival and development are provided. Among the factors that influence its effectiveness includes the type of soil or culture substrate, which works as an energy source reserve. Therefore, a tomato and a melon crop were established in different cycles to assess the effect of the physicochemical properties of organic substrates based on coconut fibre and vermicompost in three proportions, 0:100, 40:60 and 60:40 (% v:v), on the microbial activity in the rhizosphere when the bacteria Azotobacter vinelandii, Bacillus megaterium and Frateuria aurantia were applied. Concentrations of NO3−, H2PO4−, K+ and Ca2+ in the petiole cellular extract (PCE) were quantified at 60, 90 and 120 days after transplantation (DAT) for tomato and 45 and 65 DAT for melon. We analysed dehydrogenase activity (DHA), acid phosphatase activity (FTA) and β-glucosidase activity (β-GLU). In order to maintain optimal volumetric moisture for the survival of microorganisms, automatic control was used to manage the irrigation frequency between 22%–28%. The results showed that physicochemical substrate properties, by incorporating 40% vermicompost into the coconut fibre mixture, increased enzymatic activity. Plants that were inoculated with Azotobacter vinelandii and Frateuria aurantia showed an improvement in NO3− and K+ assimilation achieving highest yields.

Evaluation of Organic Substrates and Microorganisms as Bio-Fertilisation Tool in Container Crop Production

Oil activity has generated severe problems of soil contamination. Different techniques have been employed for the removal of pollutants, which are mainly used separately as treatments, but if combi...

Fenton-biostimulation sequential treatment of a petroleum-contaminated soil amended with oil palm bagasse (Elaeis guineensis)

The activity of 4 soil enzymes in farms under different agronomic managements and in different soil types was analyzed The enzymes tested were phosphatase, β-glucosidase, dehydrogenase and urease Soil samples were taken from the first 20 cm in depth, in order to determine the activity of the 4 enzymes and analyze them chemically It was found that Dehydrogenase enzyme activity ranged from 013 to 446 with an average of 117 (μg INTFg - 1 h -1 ); β-glucosidase enzyme ranged from 319 to 2081 with an average of 1081 (μg PNPg -1 h -1 ) Furthermore, phosphatase had values between 4134 and 30436 with an average of 15215 μg PNPg -1 h -1 , while Urease ranged from 125 to 528 with an average of 383 μg N-NH4g -1 h -1  Phosphatase correlated with the percentage of organic matter and carbon in the soil (075 and 076 respectively, p<001); an inverse relationship was found between the activity of this enzyme and the content of available P (-053r, significant at p<010) Urease correlated with phosphatase (r=061 p<005) and with dehydrogenase (r-077 p<001) Multivariate cluster analysis based on the enzymatic activity allowed to make similar groups according to the type of crop, which shows the potential of usage that this property has for undertaking more detailed studies

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Arturo Valenciano

Papers

Actividad enzimática del suelo -Deshidrogenasa, β-Glucosidasa, Fosfatasa y Ureasa- bajo diferentes cultivos

Activid Ad enzimátic A del suelo - deshidrogenAs A, -glucosid As A, Fos FAt As A y u re As A- bAjo di Ferentes cultivos

Soil enzyme activity -Dehidrogenase, ß-glucosidase, Phosphatase and Urease- under different crops