Determinación de factores de enriquecimiento y geoacumulación de Cd, Cr, Cu, Ni, Pb, y Zn en suelos de la cuenca alta del río Lerma

Se determinó el índice degeoacumulación regional (Igeo) y el factor deenriquecimiento (EF) en suelos irrigados de lacuenca alta del río Lerma, Estado de México.Se colectaron 55 muestras de suelo de cincolocalidades: Tlachaloya, Ixtlahuaca,Atlacomulco, Temascalcingo y Amealco. Laspropiedades químicas analizadas fueron pH,capacidad de intercambio catiónico, arcilla,materia orgánica, concentración de Cr, Cu, Cd,Ni, Zn, y Pb; así como el Igeo y FE. Los suelosse consideraron excelentes para su usoagrícola en cuanto a los valores de pH ymateria orgánica (MO). Las concentraciones demetales pesados se encontraron por debajo delos límites permisibles. De acuerdo con elfactor de enriquecimiento, el Pb se considerócomo un contaminante moderado con unorigen tanto geológico como antropogénico.El índice de geocumulación mostró que el Pby el Ni son los mayores contaminantes del suelo.Se determinó el índice de geoacumulación regional (I geo) y el factor de enriquecimiento (EF) en suelos irrigados de la cuenca alta del río Lerma, Estado de México. Se colectaron 55 muestras de suelo de cinco localidades: Tlachaloya, Ixtlahuaca, Atlacomulco, Temascalcingo y Amealco. Las propiedades químicas analizadas fueron pH, capacidad de intercambio catiónico, arcilla, materia orgánica, concentración de Cr, Cu, Cd, Ni, Zn, y Pb; así como el I geo y FE. Los suelos se consideraron excelentes para su uso agrícola en cuanto a los valores de pH y materia orgánica (MO). Las concentraciones de metales pesados se encontraron por debajo de los límites permisibles. De acuerdo con el factor de enriquecimiento, el Pb se consideró como un contaminante moderado con un origen tanto geológico como antropogénico. El índice de geocumulación mostró que el Pb y el Ni son los mayores contaminantes del suel

Microbiological and biochemical properties of an agricultural Mexican soil amended with sewage sludge

The application of sewage sludge is a concern because it may affect the quality of organic matter and microbiological and biochemical soil properties. The effects of surface application of sewage sludge to an agricultural soil (at 18 and 36 t ha-1 dry basis) were assessed in one maize (Zea mays L.) growing season. The study evaluated microbial biomass, basal respiration and selected enzymatic activities (catalase, urease, acid and alkaline phosphatase, and β-glucosidase) 230 days after sewage sludge application and infrared spectroscopy was used to assess the quality of dissolved organic matter and humic acids. Sewage sludge applications increased the band intensity assigned to polysaccharides, carboxylic acids, amides and lignin groups in the soil. The organic matter from the sewage sludge had a significant influence on the soil microbial biomass; nevertheless, at the end of the experiment the equilibrium of the soil microbial biomass (defined as microbial metabolic quotient, qCO2) was recovered. Soil urease, acid and alkaline phosphatase activity were strongly influenced by sewage sludge applications

Effect of sewage sludge or compost on the sorption and distribution of cooper and cadmium in soil

The application of biosolids such as sewage sludge is a concern, because of the potential release of toxic metals after decomposition of the organic matter. The effect of application of sewage sludge (Sw) and compost (C) to the soil (S) on the Cu and Cd sorption, distribution and the quality of the dissolved organic matter (DOM) in the soil, was investigated under controlled conditions. Visible spectrophotometry, infrared spectroscopy, sorption isotherms (simple and competitive sorption systems), and sequential extraction methods were used. The E4/E6 (k at 465 and 665 nm) ratio and the infrared spectra (IR) of DOM showed an aromatic behaviour in compost–soil (C–S); in contrast sewage sludge–soil (Sw–S) showed an aliphatic behaviour. Application of either Sw or C increased the Cu sorption capacity of soil. The Cd sorption decreased only in soil with a competitive metal system. The availability of Cu was low due to its occurrence in the acid soluble fraction (F3). The Cu concentration varied in accordance with the amounts of Cu added. The highest Cd concentration was found in the exchangeable fraction (F2). The Sw and C applications did not increase the Cd availability in the soil

Abono orgánico elaborado con lodo residual y estiércol equino a través de vermicomposteo: una propuesta como mejorador de suelos

Se elaboró un abono orgánico con estiercol equino y lodo residual y diferentes mezclas de estos, y la que tuvo los mejors resultados como mejorador de suelos fue la relación 70:30 estiercol equino-lodo residual, siendo medida por diferentes parametros físicos, químicos y metales pesados.Las actividades humanas producen toneladas de residuos sólidos orgánicos que causan problemas al ambiente, como la contaminación de suelo, agua y mantos freáticos. Ante esto, se han desarrollado estrategias como el vermicomposteo, proceso de estabilización de residuos sólidos orgánicos. El presente estudio tiene como objetivo probar mezclas de lodo residual y estiércol equino en diferentes porcentajes, por medio de vermicomposteo, para conocer su estabilidad y proponerlo como mejorador de suelo. Para su elaboración se utilizaron cuatro porcentajes de estiércol equino y lodo residual: E100, E85-LR15, E70-LR30 y E55-LR45 y se dio un seguimiento durante 90 días bajo condiciones de invernadero. El producto mostró disminución gradual en el porcentaje de C orgánico, relación C:N y pH. Se incrementó el contenido de N total a los 30 días y la conductividad eléctrica a los 75 días. El P aumentó para E70-LR30 (57.3 ± 8.3 mg/kg a 1369.8 ± 114.8 mg/kg) al final. A los 45 días se alcanzó la estabilidad de las vermicompostas en cuanto a la relación C:N: E100 (11.4); E85-LR15 (10.8); E70-LR30 (12.6) y E55-LR45 (11.2). La mejor relación es E70-LR30, ya que presenta un balance en el aporte de N y C, la concentración de metales pesados disminuyó para Cu, Zn, Ni y Cd, además el pH que presentó (7.24 ± 0.1) fue neutro, la concentración de P se incrementó considerablemente y el número de lombrices fue mayor (1790) con respecto a los otros tratamientos, por lo que esta relación es adecuada para su uso como abono orgánico

Assessment of Soil Parameters Related With Soil Quality in Agricultural Systems

The native vegetation in the central highlands of México is being increasingly replaced by agricultural crops; with conventional agricultural practices consisting of intensive tillage, and monocultures, with the subsequent removal of crop residues which have led to soil deterioration and loss of its natural fertility. Studies dealing with soil transformations followed by different land use practices are crucial for the selection of adequate management practices in order to rehabilitate soil efficiency and to maintain sustainability of the system. The aim of this study is the characterization of different soils (cultivated, forest, and reforested) aiming to identify key indicators of soil quality for Andosols in order to elaborate an index of soil quality. The study was conducted in Calimaya area, central Mexico, using five soils under different vegetation: maize (Zea mays L.), oat (Avena sativa L.), potato (Solanum tuberosum L.), a forest soil (Alnus acuminata) with minimal human disturbance and reforested site (Cupressus lusitanica). A series of physical, chemical and biological properties of the soils were analyzed: water holding capacity (WHC), texture, bulk density (BD), pH, organic matter (OM) content, total nitrogen (TN), electrical conductivity (EC), nitrogen mineralization (Nm), microbial biomass carbon (MBC), basal respiration (CO2) and enzymatic activities (catalase, urease and acid phosphatase). The results suggested a soil index based on the parameters: TN, OM and acid phosphatase, which showed comparatively large weight in the factorial analysis including all the parameters analyzed

Heavy metals in soil treated with sewage sludge composting, their effects on yield and uptake of broad bean seeds (Vicia faba, L.)

The final use that may be given to biosolids that result from the treatment of residual municipal waters depends on their physicochemical and microbiological characteristics. Their organic matter content and wealth of essential elements may allow their use for agricultural fertilization purposes. The objective of this research project was to evaluate the physicochemical interactions between soil treated with biosolids and compost from municipal residual waters, and the nutritional parameters of broad bean seeds (Vicia faba L.). The studied area is located in the central region of the Mexican Republic. The biosolids were treated with aerated static pile composting. The experimental work was performed in the area surrounding the East Toluca Macroplant, where nine 2 × 3m plots were defined and distributed in a Latin square; 3 plots were used as controls (without conditioning), 3 were conditioned with 4.5Mgha−1 of biosolids on a dry base, and 3 were conditioned with the same amount of compost. The parameters determined for biosolids, compost, and soil were: pH, electrical conductivity (EC), organic matter (OM), total nitrogen, available phosphorus, cation exchange capacity (CEC), exchangeable cations (Ca, Mg, Na and K), total and available heavy metals (Cd, Cr, Cu, Ni and Zn); for the plant: height reached, green seeds productivity and yield per treatment (ton ha−1); for the seeds: humidity, ashes, fiber, fats, protein, starch and total and available heavy metals (Cd, Cr, Cu, Ni and Zn). pH was slightly acid in soil treated with biosolids (6.71). OM and CEC did not represent significant differences. Total concentrations of Cr, Zn, Ni and Cu in soil presented significant differences (p < 0.05) between treated soil and the control, Cd was not detected. Cu was the most available metal in soil treated with compost (15.31%), Cd and Cr were not detected. The plants had higher growth rates with biosolids (112.22 cm) and compost (103.73 cm); higher Green broad bean productivity and higher seed yield, especially in plots containing biosolids, which had rates three times higher than the control. In regards to broad bean seeds, content of ashes, fiber, fats, protein, starch and heavy metals (Cu, Ni and Zn), there were no significant differences between the treatments. Cd and Cr were not detected. In conclusion, it has been proven that the use of biosolids and compost studied in this broad bean crop do not involve an environmental risk, and thus give way to a solution to the problem of final disposition of biosolids in the region

Effects of sewage sludge and sewage sludge compost amendment on soil properties and zea mays l. plants (heavy metals, quality and productivity)

The use of organic wastes in agriculture can improve the soil's productive capacity, and physical and chemical characteristics. This study evaluated the effects of sewage sludge, sewage sludge compost and inorganic fertilizer applications on nickel, copper and zinc contents in soil and corn grains (Zea mays L); maize productivity, and grain nutritional quality. Sewage sludge and sewage sludge compost at 18 Mg ha¿1 and a mineral fertilizer (N-P-K) with a formulation of 150-75-30 were applied. Significant differences were observed in organic matter, phosphorus and zinc content between sewage sludge-soil and compost-soil, and inorganic fertilizer-soil (P < 0.05). Copper concentration was significantly high in compost-soil (P < 0.05). Productivity in compost-soil and sewage sludge-soil mixtures was higher than in inorganic fertilizer-soil. Grain quality, measured by relative percentage of starch, total nitrogen, protein, acid detergent fiber and neutral detergent fiber were adequate for human consumption. Application of sewage sludge or compost did not increase heavy metal concentrations in grain with respect to inorganic fertilizer-soil

Bactericidal effect of silver nanoparticles against propagation of Clavibacter michiganensis infection in Lycopersicon esculentum Mill

El estudio explora el uso de nanoparticulas de plata como bactericida contra Clavibacter michiganensis en jitomate. Se encontró una concentración optima y se puede señalar a estas nanoparticluas como inhibidor de bacterias.This study explored the use of silver nanoparticle as a bactericidal against the propagation of Clavibacter michiganensis onto tomatoes (Lycopersicon esculentum Mill). In Mexico, tomato production covers about 73% of the total vegetable production but it is affected by outbreak of bacteria canker caused by Clavibacter michiganensis subspecies michiganensis (Cmm). Silver ions possess inhibitor properties, bactericides and high specter antimicrobials. In this study, 6 groups of culture were prepared using 6 different petri dishes where silver nanoparticles of varying concentrations (120, 84, 48, 24, 12 and 0 μg) were added. Furthermore, each group was observed for 20 min, 1, 2, 12 and 24 h. The optimum concentration is 84 μg, which shows an average of 2 Cmm colonies after 20 min. Further increase to 120 μg shows no significant change. However, the average colonies was observed for 48 μg after 1, 2, 12, and 24 h. The obtained results indicate that silver nanoparticles are a promising inhibitor, bactericide and high a specter antimicrobial for treatment or prevention of Cmm

Quality and time of biosolid compost when varying ratios and weight of substrates

Introduction: Biosolids generated in the treatment of wastewater are an environmental problem due to their inadequate handling and disposal. Objective: To know the effects when varying substrate ratios and pile weight on quality and time of biosolid compost. Materials and Methods: The mixture of biosolids (BS) with clay soil (CS) and equine degraded manure (DM) was evaluated in the following ratios: 70:30:00, 65:30:05, 60:30:10 and 50:30:20 to determine the optimum ratio in piles of 250 kg and evaluate it in 500 and 2 000 kg. The parameters of quality were temperature, Ph, humidity, organic matter (OM), total Kjeldahl nitrogen (TKN), C/N ratio, K/Na ratio and phosphorus (P). Results and Discussion: the ratio 65:30:05 had higher temperature (63.8 °C) and lower composting time (21 days). Significant differences ( P < 0.05) were found in the parameters of quality with respect to the substrates and pile weight. The treatments of 250 kg had the shortest processing time (28 days) with higher OM, TKN, C/N and P. Conclusion: The DM and CS favor BS composting by reducing the process to a maximum of 32 days. The ratio 65:30:05 in 250 kg increases the agronomic quality of the compost

Effect of organic selenium supplementation in the diets of finishing sheep on meat color and pH during shelf life

Supplementation of Selenium (Se) can improve the oxidative stability of meat products and retard metmyoglobin formation; so prolonging color. Effect of organic Se addition in the diets of sheep on meat stability; color and pH are limited and need to be studied. A study was conducted with eighteen Pelibuey female sheep at the finishing stage, and supplemented with organic Se-enriched Saccharomyces cerevisiae for sixty days to evaluate its effect on color and pH of Longissimus dorsi muscle. The research was conducted in a block randomized design considering three treatments; control (Se0) without the addition of yeast, or with 0.35 ppm of yeast (Se34) or with 0.60 ppm (Se59). Sheep were slaughtered at an average weight of 39.5 ± 4.41 kg. Meat color and pH were recorder in the cold carcass, 24 h after slaughtering, and during shelf life at 0, 4, 6 and 8 days after slaughtering under refrigeration at 4 °C. No significant differences were observed (P>0.05) for meat color and pH characteristics due to treatment. Decreased redness (a*) and Chroma (C*) values due to storage time were observed; however, the yellowness (b*) and angle Hue were increased. It could be concluded that supplementation of Seenriched yeast in finishing sheep with 0.35 ppm and 0.60 ppm has no effect on meat color and pH characteristics