vol. 10 núm. 2 (2019)

The purpose of this research was to collect, codify and taxonomically identify the arthropod individuals found in 45 samples of three farms, under coffee cultivation, planted in organic, conventional and mixed system, in the municipality of Líbano (Tolima, Colombia) during 2014, in an investigation on the exergy. It was obtained that soil arthropods (including mulch and surface leaf litter) of the conventional farm (Type I) had a higher index of diversity than the organic farm and the latter had a higher index than the mixed farm. In spite of this, the organic farm has a greater population of arthropods that double the populations of conventional farms and five times those of the mixed farm, which demonstrates the high interaction between arthropods and the dynamics of organic matter, in the role of transformation of lignocelulitic macromolecules and diversity residue, towards more mineralized forms and in search of the standard C / N ratio of nature.

The feeding behavior in the giant otter (Pteronura brasiliensis) has been described by several authors, however, the coordinated way in which the otter takes part in the hunting and obtains his feeding, has not been studied in detail. This paper systematizes the information of observations on the hunting behavior of Pteronura brasiliensis, in the Sapuara lagoon in the department of Guanía, Colombia, and allowed to describe hunting as a cooperative and highly organized behavior. This behavior has been studied through ad-libitum observations, from rocks and trees of 10 to 20 meters high with a horizontal viewing range of 110º. Some of the parameters analyzed were fishing strategy, type of shore, time spent on fishing, number of active otters (otters that participated in the fishing), depth, climatic conditions, and effectiveness of hunting. In the end, 11 cooperative fishing behaviors were observed, which were classified into three groups: Arrowhead, ranks and rounding. The most frequent of all those observed in farm work was arrowhead with a percentage of 38 %, with an average number of 7 otters participating in the hunt and with a success rate of up to 87 %. This is a new instrument for the approach of the study of the behavior of P. brasiliensis from the cooperative perspective of hunting.

From a governmental perspective, where the state is the owner of forests, regulatory frameworks for forest management are typically asymmetric in relation to the dynamics of the local community. This research identifies, by using study cases, the relationship form of the human being with the forest, in order to establish the favorable aspects and the barriers that face the materialization of the self-management as the base of effective governance in the management of the natural tropical forests. The review of 60 case studies was addressed, of which only 26 present a conceptual systematization with specific features of the principles proposed by Ostrom for “resources of common use” (RCU). The analysis concludes that the most recurrent principle in the studies is the "coherence between rules of appropriation and provision", while the least considered is the "monitoring of resources", which shows that communities always establish rules; however, the importance of monitoring is not clear for them.

The onion is one of the most cultivated and consumed vegetables worldwide. In Colombia its seed is concentrated in the departments of Boyacá and Cundinamarca. However, this crop currently presents problems of plagues, diseases and low mineral nutrition. The good supply of macro and micronutrients is essential for the plant to develop its metabolic processes properly. Within the macronutrients, phosphorus (P) plays an important role since it is part of the transfer of energy in the metabolic processes and synthesis of the cellular structures of plants. For this reason the aim of the research was to evaluate an unconventional source of phosphorus in onion plants (Allium cepa L.) under field conditions, for which a completely randomized design was used with four treatments that consisted in the application of a thermal phosphate in different percentages The physiological and growth variables evaluated were: fresh and dry foliar, and bulb mass, leaf area, phosphorus, calcium and magnesium foliar content, and yield. There were significant differences (P ≤ 0.05) in the variables foliar and bulb fresh mass, bulb dry mass, leaf area, magnesium leaf content and yield versus the application of a conventional source, this converts the thermal phosphate into an alternative to take into account within the fertilization plans of semi-annual crops within a mineral nutrition scheme under the study conditions.

Livestock activities, in addition to using large volumes of water generate a high load of pollutants, especially of organic type, which arrive directly at natural water sources altering their quality. Due to the above, the aim of the following research was to find the optimal operating conditions of a heterogeneous photocatalysis system with TiO2 mediated with sunlight for the treatment of wastewater from the cattle bath; For this purpose, two pH levels (5.0 and 7.0) and two levels of TiO2 concentration (0.4 and 0.6 g/L) were specified. In each treatment, 40 L of the wastewater was recirculated in a solar composite parabolic collector for 240 minutes. The efficiency of the system and the kinetics of degradation were determined in terms of chemical oxygen demand (COD). The COD removals in the treatments were greater than 50 %, while the Taguchi experimental design and the best signal/noise ratio (RS/R) showed that the optimal operating conditions are obtained for a pH equal to 5.0 and a concentration of TiO2 of 0.6 g/L reaching removals of 83.2%. The degradation kinetics was of first order with higher reaction rates for the highest amounts of accumulated UV (> 142.9 W h/m2). Therefore, heterogeneous photocatalysis with TiO2 mediated by sunlight turns out to be a viable treatment for the removal of organic pollutants in effluents affected by the development of livestock activities.

To evaluate dynamics in nutritional composition of tropical forages used in cattle production in Colombia a systematic research was made, using a regular search engine, for studies published in Colombia between 1985 and 2015, Those studies had to include chemical composition data, such as crude protein, neutral detergent fiber, acid detergent fiber and in vitro dry matter digestibility (CP, NDF, ADF, IVDMD). Likewise studies that reported productive parameters such as daily weight gain (DWG Kg/d), milk yield (MY Lt/d), Animals per hectare (UGG/ha), were included. A lineal regression model was used for chemical components and productive parameters for the period studied. Starting from the global research, 105 studies were included from 17 research database, from which 9 species were selected (species with more than 5 studies published). No lineal trends were observed in the time lapse analyzed, for neither chemicals fractions nor productive parameters related to forage quality. However for Brachiaria sp and Paspalum sp a positive trend was detected for UGG/ha (r2=0.54 y 0.53,respectively). Despite the low significance of the coefficients of determination of lineal regression model for the 9 species selected, an overall lineal increase in CP and IVDMD was observed, and also a lineal reduction for ADF (except for Lolium sp and Dichantium sp). Regarding to productive parameters, a slight positive trend was observed for the UGG/ha in most of the species analyzed. This kind of study becomes in a valuable tool in order to explain and to predict the nutritional behavior of the forage species and its effect on livestock productive parameters.

Several studies in microalgae cultures show the relation between the photosynthetic efficiency and agitation, this effect was evaluated in solar collectors for tubular photobioreactors, which have different geometries in cross section (circular, octagonal, hexagonal and square). In this work, a computational study of microalgae culture (single-phase flow) for each of these solar collectors with a hydraulic diameter of 2 in, 100 in of length and six different culture inlet velocities to the collector (0.25 to 0.5 m/s) are performed to set the influence of profiles on the fluid behavior. The speed, pressure drop, secondary flow and shear stress was analyzed, establishing that the collector with hexagonal profile provides better agitation due to the irregular geometry, but the inlet velocities of the culture must be used in the collector for less than 0.3 m/s to ensure a continuous growth model of microalgae according to the literature tendency. It was found, under this operation regime, that the shear stress values do not cause damage to the wall cell of the microalgae making this implementation feasible in pilot plants.

The objective of this article was to develop a model for the dynamic management assessment of the ordinary waste of Bogota and to assess its influence in the indicators of used and properly disposed waste, which are part of the Urban Environmental Quality Index. For the construction of the model, the Systems Dynamic methodology was applied, which allowed the assessment of different management scenarios. Four scenarios were proposed: the first one represented the increase in the separation at the source; the second one showed an increase of 20 % in the recycling; the third one collected the previous two; and, finally, the fourth one looked for encouraging the separation at the source and bring to 50 % the recycling. Considering the model simulations, it is evident that it is urgent to elaborate education strategies for the population to promote the separation at the source; furthermore, it is important to improve the recycling in order to impact the landfill life and to improve the analyzed indicators.

En la actualidad los retos de la escritura científica son mas diversos, pero la verdad para cualquier investigador de alto reconocimiento académico solo dirá desde su experiencia“la única forma de aprender a escribir es haciéndolo” sin embargo, la escritura científicase vuelve hasta cierto modo subjetiva, porque depende de los intereses de la revista, susáreas de especialidad, intereses de autores y factores de impacto tanto de la revista comodel mismo autor, aspecto predominante en la visibilización científica.

This document is focused on the generation of compost through the use of the Eisenia Foetida earthworm (Oligochaetes: Lumbricidae), which, at suitable metabolic conditions, promote the degradation of organic solid waste. This project evaluates the process of obtaining compost from organic solid waste generated in Álamos neighborhood, Bogotá, Colombia, through joint work with the community, in order to determine the amount of natural fertilizer that can be produced in the sector, in line with the policies of national organizations that intend to introduce the separation and use of households waste. It was established that organic waste accounts for 30 % of the waste generated in the sector, from which three worm farming beds were designed, with different substrates, the bed with the highest proportion (60 %) of cassava and potato residues being the one that produced the greater yield respect to the compost obtained. Regarding the quality of the product, the results obtained are similar in all the beds, reaching an excess of total nitrogen with respect to that required for commercialization. The results also present excess humidity, which suggests a drying process after obtaining the compost is needed.

The design of a model for collective construction for rurality aims to make visible the relevance and quality of education at different level. This includes the participation of specialized and nonspecialized social actors, giving an account of the steps followed to develop a collaborative model of rural higher education of the Northeast of Antioquia. In addition, it includes higher education institutions in the region, which come together to develop, in the first phase, a diploma course, where appropriate, the definitions and conceptualize the relevance of educational models. In the second phase, short courses are developed with the implementation of trends, and approach to the sociocultural context that will lead to the model and adaptability. Interrelating culture, development and significance in context, wealth of behaviors  with an exploratory methodology (qualitative), with the aim of improving conditions of affordability, coverage and educational quality, from the range of social realities. In the third phase, a collaborative model based on modules is built within the framework of a flexible curriculum and sociocultural alternative that tends towards the reconstruction of social fabric. In conclusion, the model for the collective construction of knowledge for rurality is designed collectively proposing flexible curricula, creative and innovative didactic with prospective transformation of sociocultural context.