La materia orgánica es un parámetro importante, que se utiliza como indicador de calidad del suelo y está relacionado directamente con las propiedades físicas, químicas y biológicas del suelo. Además su cuantificación se requiere para recomendar la cantidad y el tipo de enmiendas que se debe aplicar al suelo. En el presente artículo se compararon dos procedimientos para cuantificar este parámetro. El primero se hizo determinando la materia orgánica por un método químico de la norma NTC 5403 oxidación húmeda propuesto por Walkley y Black en 1934. El segundo método utilizado fue por calcinación llevando las muestras a una mufla por un periodo de dos horas a 360 °C y obteniendo los valores por diferencias de peso. Se compararon las muestras encontrando una alta correlación entre los dos métodos con un coeficiente de determinación de 0.902. Lo anterior indica que se puede obtener los contenidos de materia orgánica por calcinación ahorrando tiempo y recursos, pues su determinación está relacionada con el contenido de humedad del suelo, la densidad aparente y la calidad del suelo.

Microplastics (MP) are widespread pollutants that pose a risk to soil ecosystems globally, especially in agricultural soils. This study introduces a method to extract and identify MP in Brazilian tropical soils, targeting debris of low-density polyethylene (LDPE) and polyvinyl chloride (PVC) polymers, commonly present in agricultural settings. The method involves removing organic matter and extracting MP using density separation with three flotation solutions: distilled water, NaCl, and ZnCl₂. Extracted MP are then analyzed through optical microscopy and Fourier transform infrared spectroscopy. The organic matter removal efficiency ranged from 46% to 89%, depending on the initial organic matter content in the soil. Recovery rates for LDPE ranged from 81.0% to 98.8%, while PVC samples showed a range of 59.7% to 75.2%. Finally, this methodology was tested in four agricultural raw soil samples (i.e., without any polymer enrichment) The values found in the soil samples were 2517.5, 2245.0, 3867.5, and 1725.0 items kg⁻¹, for ferralsol, nitisol, gleysol, and cambisol samples, respectively, with MP having diverse shapes including fragments, granules, films, and fibers. This approach lays the groundwork for future studies on MP behavior in Brazilian tropical agricultural soils.

The assessment of microplastics (MPs) in terrestrial ecosystems has garnered increasing global attention due to their accumulation and migration in soils, which may have potential impacts on soil health, biodiversity, and agricultural productivity. However, research on their distribution and interactions in soil remains limited, especially in tropical regions. This study aimed to characterize MPs extracted from tropical soil samples and relate their abundance to soil and terrain attributes under different land uses (forest, grassland, and agriculture). Soil samples were collected from an experimental farm in Lavras, Minas Gerais, Southeastern Brazil, to determine soil physical and chemical attributes and MP abundance in a micro-watershed. These locations were also used to obtain terrain attributes from a digital elevation model and the normalized difference vegetation index (NDVI). The majority of microplastics found in all samples were identified as polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), and vinyl polychloride (PVC). The spatial distribution of MP was rather heterogeneous, with average abundances of 3826, 2553, and 3406 pieces kg⁻¹ under forest, grassland, and agriculture, respectively. MP abundance was positively related to macroporosity and sand content and negatively related to clay content and most chemical attributes. Regarding terrain attributes, MP abundance was negatively correlated with plan curvature, convergence index, and vertical distance to channel network, and positively related to topographic wetness index. These findings indicate that continuous water fluxes at both the landscape and soil surface scales play a key role, suggesting a tendency for higher MP accumulation in lower-lying areas and soils with greater porosity. These conditions promote MP transport and accumulation through surface runoff and facilitate their entry into the soil.

The municipality of Facatativa, where the research was carried out, is located in the Bogota Plateau (Department of Cundinamarca), an area specialized in the production of flowers that, along with other producing regions of the department, represent around 72% of national production. Establishing the amount of water and the time of application is a key factor that contributes to obtain the quality and production required, according to the requirements in commercial crops, such as rose. The main objective of this study was to evaluate the effect of three irrigation depths on Rosa sp. Vendela variety in substrate (80% toasted rice husks and 20% compost), based on evapotranspiration and percentage of drainage, in a greenhouse in the Bogota Plateau. The experiment was conducted in two crop cycles during 2014. The production and quality of the harvest were evaluated with three irrigation depths: Control treatment (T1) with 100% of the crop’s evapotranspiration (ETc) and drainage percentage (% D), T2 and T3, equivalent to 80% and 65% of T1, respectively. Irrigation was applied as follows: 15.04, 12.39 and 10.35 m3 per bed were applied for two cycles in T1, T2 and T3, representing a reduction of 17.6 and 31.2% for T2 and T3, respectively, compared to the control treatment. The production of floral stems, the bud diameter and length did not have significant differences (P<0.05) according to the Duncan test; however, T1 had the highest number of stems. The length and diameter of the stem, the crop coefficient Kc and water use efficiency (WUE) presented significant differences between the treatments. The growth curves showed a continuous increase, which fit the logistic model.