ABSTRACT. In the conventional management of the soil for floricultural use, practices such as tillage, irrigation, the application of agrochemicals, among others, are used that favor yields, but also alter the physical, chemical and biological characteristics of the soil, which in turn are correlated with the CO2 given off by its microbial activity. Therefore, the objective was to determine the CO2 emission and relate it to the biochemical properties in greenhouse horticultural crops. The CO2 emitted was measured with the modified alkali trap technique, while the biochemical, physical and chemical properties were determined by traditional methods. The differences between the chemical variables (pH, electrical conductivity and organic matter) may be due to the management conditions, evidence was also observed that the management of each crop had an effect on the biological activity of the soil with changes in the emission of CO2 in the two times of sampling, the tomato crop being the one with the highest value. CO2 emissions peaked after irrigation due to moisture that increased soil microbial activity. There was little variation in N mineralization for both sampling times. Management was also related to changes in microbial biomass carbon and the qCO2 index, biochemical parameters were modified by the use of agrochemicals, moisture content and organic matter.

RESUMEN. En el manejo convencional del suelo de uso hortícola se emplean prácticas como la labranza, el riego, la aplicación de agroquímicos, entre otros, que favorecen los rendimientos, pero también alteran las características físicas, químicas y biológicas del suelo que a su vez están correlacionadas con el CO2 que se desprende por la actividad microbiana del mismo. Por lo anterior, el objetivo fue determinar la emisión de CO2 y relacionarlo con las propiedades bioquímicas en cultivos hortícolas en invernadero. Se midió el CO2 emitido con la técnica de trampa de álcali, modificada, mientras que las propiedades bioquímicas, físicas y químicas se determinaron por los métodos tradicionales. Las diferencias entre las variables químicas (pH, conductividad eléctrica y materia orgánica) pueden deberse a las condiciones de manejo, también se observaron evidencias que el manejo de cada cultivo tuvo efecto en la actividad biológica del suelo con cambios en la emisión del CO2 en las dos épocas de muestreos, siendo el cultivo de jitomate el de mayor valor. Las emisiones del CO2 tuvieron un pico después del riego debido a la humedad que incrementó la actividad microbiana del suelo. Se tuvo poca variación en la mineralización de N para ambas épocas de muestreo. También el manejo se relacionó con los cambios del carbono biomasa microbiana y el índice qCO2, los parámetros bioquímicos se vieron modificados por el uso de agroquímicos, contenido de humedad y de materia orgánica.

A aplicação de lodo de esgoto é uma preocupação, devido aos seus efeitos sobre a matéria orgânica e a qualidade microbiológica e bioquímica do solo. O efeito da aplicação de lodo de esgoto em um solo agrícola foi estudado em um ciclo de crescimento de milho (Zea mays L.) em taxas equivalentes a 18 e 36 t ha-1 ano-1(base seca). O experimento foi conduzido para avaliação de biomassa microbiana, atividade respiratória microbiana e atividades enzimáticas (catalase, urease, fosfatases ácida e alcalina e β-glicosidase) até 230 dias após a aplicação de lodo de esgoto; a espectroscopia de infravermelho foi utilizada neste estudo para avaliação da qualidade da matéria orgânica dissolvida e de ácidos húmicos. A aplicação de lodo de esgoto aumentou a intensidade das bandas atribuídas aos grupos de polissacarídeos, ácidos carboxílicos, amidas e ligninas no solo. A matéria orgânica do lodo de esgoto teve influência significativa na biomassa microbiana do solo. No entanto, no final do experimento a biomassa microbiana do solo recuperou sua condição de equilíbrio (quociente metabólico microbiano, qCO2). As enzimas urease e fosfatases ácida e alcalina foram fortemente influenciadas pela adição de lodo de esgoto.

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.

Heavy metals (MP) are part of the pollutants contained in the leachate, which is generated by the decomposition of municipal solid wastes (RSU), which it by toxicity causing severe problems to the environment. The objective of this study was to determinate the effect of different rates of leachate recirculation in the concentration of MP, and in the waste of the matrix of anaerobic bioreactors (BrA) at laboratory scale, to determinate the rate that produced a minor leaching of MP. There were used 20 BrA with RSU from landfill of Patzcuaro, Michoacan, Mexico; four as controls, and for the other 16, its leachates were recirculated twice a week in order to keep the moisture contents of 50, 60, 70, 80% wet basis (% Hbh) by quadruplicate. The leachates that were produced were followed for 126 days, and pH and total heavy metals (MPT) were determined. pH, organic matter (MO), MPT and available heavy metals (MPD), Ni, Pb and Zn were determined in solid discharges wastes. On the other hand, the leachate generated at 80 and 70% Hbh showed less lixiviation of HM, whereas 50% Hbh during hydrolysis and acidogenic phases showed high concentrations of HM. For MPT in solid waste, Ni and Pb, they showed significant differences among the samples, and regarding to the MPD, there were only significant differences in Zn. The solid waste recycling of all rates can be used as soil amendments for its high content of MO and low metal concentration.

Los metales pesados (MP) son parte de los contaminantes que contiene el lixiviado, este es generado por la descomposición de los residuos sólidos urbanos (RSU), el cual por su toxicidad puede causar severos problemas al ambiente. El propósito de este trabajo fue conocer el efecto de diferentes tasas de recirculación de lixiviados en la concentración de MP, así como en la matriz de residuos de biorreactores anaerobios (BrA) a escala laboratorio, para determinar la tasa que produzca la menor lixiviación de MP. Se utilizaron 20 BrA con RSU del relleno sanitario de Pátzcuaro, Michoacán, México; cuatro como testigos y al resto se les recircularon sus lixiviados dos veces por semana, para mantener los contenidos de humedad de 50, 60, 70 y 80 % base húmeda (%Hbh) por cuadruplicado. Se dio seguimiento durante 126 días a los lixiviados producidos, a los cuales se les determinó pH y metales pesados totales (MPT). A los residuos sólidos descargados se les determinó pH, materia orgánica (MO), MPT y metales pesados disponibles (MPD), Ni, Pb y Zn. Los lixiviados generados a 80 y 70 % Hbh, presentaron menor lixiviación de MP, mientras que a 50 % Hbh durante las fases de hidrólisis y acidogénesis mostraron concentraciones elevadas. Para MPT en los residuos sólidos, Ni y Pb presentaron diferencias significativas entre las muestras y en cuanto a los MPD sólo existieron diferencias significativas para Zn. Los residuos sólidos de todas las tasas de recirculación pueden utilizarse como mejoradores de suelo por su alto contenido de MO y baja concentración de MP.