Agroecosystems

SOIL ORGANIC CARBON AS A FUNCTION OF LAND USES
ABSTRACT - Organic matter is one of the most sensitive attributes of the soil
triggered by changes in management systems. This study aimed to assess the
distribution and carbon stocks depending on the land use and soil depth. There were
collected soil samples from native forests, pastures and crops in ten locations, where
the three land uses are found in adjacent areas in four depths (0-10 cm, 10-20, 20-40
and 40-60 cm ). The experimental design was a Split-Plot having land uses as main
treatments and depths as secondary treatments. The highest concentration of total
soil organic carbon (SOC) was obtained in the 0 to 10 cm layer. The variation
between the mean SOC had the following order: forest (18.02 g dm-3)> grassland
(15.80 g dm-3)> agriculture (12.45 g dm-3). Between forest and pasture there was no
difference between the mean values of SOC. There was difference between soils
under forest and agriculture with a decrease of 30.91%. The concentration of
dissolved organic carbon (DOC) presented the following order between types of land
use: forest (236.42 mg dm-3)> grassland (151.41 mg dm-3)> agriculture (86.76 mg
dm-3), and showed a difference of 35.95% between forest and grassland, and
42.70% between grassland and agriculture. The highest levels of DOC were found in
the 0 to 10 cm layer and the order between types of land use was: forest> pasture>
agriculture. Same effect was obtained in the layer 10 to 20 cm and, in the layer 20 to
40 cm, difference was observed between soils under forest and soils under
agriculture, higher in the first one. There was no difference in the levels of DOC
between types of land use in the layer 40 to 60 cm. The average stock of SOC did
not differ between land uses when it was considered the depths of 0-10, 10-20, 20-
40, 40-60 and 0-60 cm. The average stock of SCO considered when the layer 0-20
cm showed a difference of 23.14% between soils under grassland (48.62 Mg ha-1)
and in agriculture (37.37 Mg ha-1). Positive correlation was found between SOC and
DOC. There was also a positive correlation between SOC and clay content. It was
concluded that the conversion of forest to pasture or crops caused decrease in SOC
and DOC. The decrease of SOC in the soil profile is less pronounced in soils under
pasture. Soils under agriculture had the lowest SOC. The superficial layers presented
the highest concentration of SOC.
Keywords: carbon stock, land use, organic matter

En pleno siglo XXI, el conocimiento de la realidad circundante continúa siendo una necesidad insoslayable, sobre todo en una temática tan trascendental como lo es la educación ambiental. Este hecho y para nuestra región geográfica, atañe esencialmente a las Universidades latinoamericanas, responsables directas de promover y desarrollar investigaciones que propongan soluciones viables a las diversas problemáticas que enfrentan nuestros países.
En consonancia con este premisa, un grupo de académicos del Centro Universitario de Occidente, de la Universidad de San Carlos de Guatemala; el Instituto de Investigaciones Socioambientales, Educativas y Humanísticas para el medio Rural (IISEHMER) perteneciente al Departamento de Sociología Rural de la Universidad Autónoma Chapingo, México y, de la Red Iberolatinoamericana y del Caribe en Educación e Intervención Ambiental para el Desarrollo (REDIILECAD A. C.), lanzaron la convocatoria a diversos académicos, estudiantes e investigadores de diversas disciplinas a contribuir con sus experiencias en investigaciones en torno a la temática medio ambiental.
En respuesta a ese desafío, la presente obra incluye el resultado de investigaciones diversas, relacionadas todas sobre la temática ambiental y que buscan atender necesidades puntuales, existentes en sus respectivos países de origen.

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