Calidad microbiológica de suelos afectados por quema/incendio en la región centro-sur de Chile.
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Date
2020
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Universidad de Concepción
Abstract
El aumento de las condiciones que favorecen la ocurrencia de incendios, los
convierte en una amenaza para sistemas agrícolas y forestales, como ocurrió en el mega incendio del 2017 en el centro sur de Chile. El efecto del fuego en la calidad del suelo en los agroecosistemas de la región ha sido poco descrito. El objetivo de este estudio fue evaluar la calidad microbiológica de suelos en sitios afectados por incendio/quemas en tres condiciones fisiográficas de la región de Ñuble: secano interior, depresión intermedia y precordillera andina. Para esto se evaluaron dos variables de suelo: respiración basal y repelencia al agua. Se tomaron muestras de suelo (0-5 y 5-10 cm) en cada uno de los sectores con la presencia del factor fuego y en ausencia del factor. Para medir la repelencia al agua se utilizaron los test de tiempo de penetración de la gota de agua y la molaridad de la gota de etanol, y para medir la respiración del suelo una incubación cerrada de suelo con trampa de álcali por 56 días a 20oC y 60% de saturación del espacio poroso de agua del suelo. Los tiempos de penetración de agua indicaron capacidad hidrofílica de los suelos (penetración < 5 s). Los valores de respiración estuvieron en el rango de 400-1000 µg C-CO2 g suelo-1 en superficie, y alrededor de 50% de estos valores en la segunda profundidad. No se encontraron diferencias significativas (P < 0,05) en la repelencia al agua entre suelos quemados y no quemados, ni en la mineralización del carbono. Por tanto, se concluye que las condiciones de los incendios/quema no fueron suficientemente severas e intensas para afectar la calidad de los suelos estudiados.
The current climate conditions increase the likelihood of fires events, becoming a threat for agricultural and forest systems, as it happened during the mega fire of 2017 in the central south of Chile. The effect of fire on soil quality in agroecosystems in the region has been poorly described. Therefore, the objective of this study was to evaluate the microbiological quality of soils in sites affected by fire / burns in three physiographic conditions of the region central south of Chile (dryland, intermediate depression, and Andean foothill).Two soil variables were evaluated: basal soil respiration and water repellency, by taking soil samples at each site with the presence of the fire factor and in the absence of the factor, at two soil depths, 0 to 5 cm and 5 to 10 cm. To measure the water repellency, the water drop penetration time tests and the molarity of the ethanol drop were used; and to measure the soil respiration a closed incubation of soil with alkali trap for 56 days at 20oC and 60% of soil water-filled pore space. The infiltration time tested showed hydrophilic water capacity of all the soils (less than 5 s). The microbial respiration range measured at the first soil layer was between 400 to 1000 µg CCO2 g soil-1, whilst half of this range was measured at 5-10 cm depth. At the threeagroecosystems, no significant differences (P < 0.05) were found in water repellency between burned and unburned soils, or in carbon mineralization. Therefore, it is concluded that the conditions of fires / burning were not as intense and severe as to affect the quality of the studied soils.
The current climate conditions increase the likelihood of fires events, becoming a threat for agricultural and forest systems, as it happened during the mega fire of 2017 in the central south of Chile. The effect of fire on soil quality in agroecosystems in the region has been poorly described. Therefore, the objective of this study was to evaluate the microbiological quality of soils in sites affected by fire / burns in three physiographic conditions of the region central south of Chile (dryland, intermediate depression, and Andean foothill).Two soil variables were evaluated: basal soil respiration and water repellency, by taking soil samples at each site with the presence of the fire factor and in the absence of the factor, at two soil depths, 0 to 5 cm and 5 to 10 cm. To measure the water repellency, the water drop penetration time tests and the molarity of the ethanol drop were used; and to measure the soil respiration a closed incubation of soil with alkali trap for 56 days at 20oC and 60% of soil water-filled pore space. The infiltration time tested showed hydrophilic water capacity of all the soils (less than 5 s). The microbial respiration range measured at the first soil layer was between 400 to 1000 µg CCO2 g soil-1, whilst half of this range was measured at 5-10 cm depth. At the threeagroecosystems, no significant differences (P < 0.05) were found in water repellency between burned and unburned soils, or in carbon mineralization. Therefore, it is concluded that the conditions of fires / burning were not as intense and severe as to affect the quality of the studied soils.
Description
Tesis presentada para optar al grado de Magíster en Ciencias Agronómicas con Mención en Ciencias del Suelo y Recursos Naturales
Keywords
Suelos - Contenido de carbono, Suelos - Calidad, Suelos - Efectos de los incendios, Suelos - Investigaciones