Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Mario Oliva se despide con una amplia bibliografía sobre diversos asuntos relacionados con la historia y la literatura centroamericana y latinoamericana. Chileno de nacimiento; vocación deja un ejemplo impecable como profesor e investigador para sus colegas del Instituto de Investigaciones Latinoamericanas (IDELA) de la Universidad Nacional de Costa Rica y para los colegas de muchas regiones que tuvimos el privilegio de conocerlo y compartir quimeras académicas.   Publicado originalmente en:  http://www.josemarti.cu/requiem-por-mario-oliva/

La materia orgánica del suelo (MOS) y su interacción con las partículas elementales del suelo (PES) determinan las tasas de mineralización, por lo que es necesario medir cuánto CO2 se libera por las fracciones elementales del suelo; sin embargo, con los métodos de fraccionamiento de las PES, se extrae una cantidad muy pequeña, lo que limita hacer ensayos de respiración con los métodos tradicionales, ya que requieren cantidades de 30 g para poder hacer mediciones en laboratorio. En este trabajo se hicieron pruebas para determinar si el equipo OxiTop es capaz de medir la respiración de muestras de suelo en cantidades pequeñas. Se colocaron cantidades de 10.0, 5.0, 1.0 y 0.5 g de muestras de mantillo (M), horizonte de fermentación (HF) y suelo (S) en frascos del equipo de 500 y 250 mL. Los resultados muestran que el equipo registra la cantidad de CO2 en todas las muestras, siendo mayores en el M que en las muestras de S. Además, el tamaño de frasco indicó que la respiración es proporcional al tamaño ya que en los frascos de 500 mL la cantidad de CO2 fue cercano al doble en comparación de los frascos de 250 mL en muestras de M y HF. En muestras de S los valores medidos en ambos frascos fueron muy similares. El equipo OxiTop es capaz de medir la emisión de CO2 en muestras pequeñas, pero el contenido de C de la muestra inf luyó, dado que, si los contenidos de C son bajos, la cantidad de CO2 será menor.

In Mexico, the productive systems of chili (Capsicum spp.) have been gradually intensif ied in order to obtain better yields and generate higher incomes, a situation that has positioned the country as the second producer and main exporter of chili in the world, generating on average per year around two billion pesos for exports; however, the intensif ication of some practices associated with this agricultural activity have generated infertility and salinization of the soil, which is why the objective of the research is to evaluate the agronomic quality of the soil in dif ferent chili-producing areas in the Calera del Aquifer region. Zacatecas state. During two consecutive cycles, soil sampling was carried out in accordance with NOM-021-RECNAT-2000 in plots destined for chili cultivation in order to determine fertility and physicochemical parameters. The results provided evidence of the variety of agrochemicals and the surplus of phosphorous and potassium fertilizers that are applied during the production cycle, a situation that considerably raises costs. The salt content found in the soil was low with a medium sodium absorption ratio, which classif ies them as C1-S2; high concentrations of sodium salts were not recorded and EC values were low, however, nutrient concentrations were very low despite the neutral pH. These characteristics can be attributed to the fact that they are soils with a high content of sand with compaction problems due to the conventional mechanized system and due to the lack of conservation strategies, therefore, the dynamics to produce chili in the region is having a negative impact. on soil quality.

In small-scale and backyard animal production systems, the evaluation of sustainability is complex, which is why various methods have been generated, one of them the indicators of the sustainability of agricultural exploitations (IDEA), which considers the agroecological, socio-territorial and economic dimensions. Backyard rabbit farming takes place in urban and suburban areas of central Mexico, which is why the objective of this research is to estimate the sustainability indicators of said activity through the IDEA method, which was adapted to be applied to this activity. livestock. Three dimensions were considered, agroecological, socio-territorial and economic, each with indicators whose maximum value is 100 points, 50 producers from the eastern zone of the State of Mexico were interviewed, the data obtained were weighted and analyzed through descriptive statistics. In the agroecological dimension (42.54) the following indicators were obtained: annual average of kits 1183, races with greater presence (62%) New Zealand, California and Mariposa, use of manure as fertilizer 66% of the producers. The socio-territorial dimension (57.82) showed that 72% of the producers have a good quality of life, in 96% of the cases family labor is used, they dedicate 2.32 hours day-1 to the activity, 86% have good relations with their community and 58% consider little intergenerational transmissibility. Finally, the economic dimension (50.24) showed that the perception of income is generated by the sale of live animals (71.7%) at a price of $93.30 m. n. per piece, carcass sales (28.2%) at $112.42 m. n. per piece and to a lesser extent, sale of rabbits and other derivatives. Based on the results, it is concluded that backyard rabbit farming is an option that can promote development in the region based on the identification and use of areas of opportunity on an agroecological scale.

In the State of Mexico, the towns near the Lerma River stand out for their industrial development, which leads to the contamination of water and soil, af fecting livestock production in the area. Based on this approach, the objective of this research work is to determine the levels of Lead (Pb) in water (mg L-1), soil and grass (mg Kg-1), for the municipalities with basins of the Lerma River, State of Mexico. The highest average levels of Pb in water were observed for El Cerrillo Vistahermosa (1.5 ± 0.4), followed by Lerma (1.0 ± 0.2) and San Pedro Tultepec (1.0 ± 0.3). The average level of Pb in water is within the permissible concentration range for water for agricultural use; however, the environmental levels are high, ref lecting an important bioaccumulation in the soil, with higher values in San Pedro Tultepec (40.7 ± 18.0) and therefore in the pasture. Lerma was the municipality with the highest concentration (38.2 ± 6.9), which makes it a source of risk for animal and human health. The localities bordering the Lerma River show notable differences in Pb levels, with higher concentrations being observed in areas with greater permanence of water in El Cerrillo Vistahermosa and San Pedro Tultepec. Finally, it was found that the Pb obtained in water, soil and grass are above the maximum permissible range in more than 50% of the samples, ref lecting an important emission of this element to the environment.

Within the framework of foreign trade, f loriculture is one of the agricultural activities that produces more high-value crops, creates more direct and indirect jobs and, consequently, generates income. In this context, the present research work aims to analyze the competitiveness at private prices of cut rose plantations, located territorially in the towns of Tenancingo and Villa Guerrero, State of Mexico. Through work carried out in the f ield, information was obtained from the organization related to costs, income, socioeconomic and market indicators during March-May 2019; Likewise, a representative sample of producers from Tenancingo and the Association of Floriculturists of Villa Guerrero A.C., with more than 29 years of work as floriculturists, was taken. For the analysis of the results, a Policy Analysis Matrix was structured in order to estimate the income, costs and prof its at private prices. The results revealed that there is no difference in production costs or prof its between the national and international markets, since the use of the properties has been prof itable and competitive, in addition to the above, in both scenarios the internal factors of production represented more than 80% of the costs, including and excluding the cost of land and labor, which represented the largest part of the resources, followed by transportation expenses. Considering that the competitiveness of the systems was based on the use of labor that replaced technological and capitalization advances, it follows that the competitiveness and profitability for both systems is marginal.

The corn-ovine production system is an alternative for producers by improving the income with ovine sale, giving an added value to corn production by feeding the sheep with grains and debris. The objective in this research was to describe the corn-ovine backyard production system of municipalities in the State of Mexico. The research was done in the municipalities of Villa Victoria and San José del Rincón in the north-east of the State of Mexico with producers who participated in the Territorial Development Program (PRODETER) “Sustainable ovine production”; the f ieldwork was from august 2019 to march 2020. This research was exploratory and descriptive. The information was obtained through interviews, visits to the production units and the application of 87 questionnaires. To analyze the information descriptive statistics was used. The results have shown that 22% were surveyed women and 78% were men with an average age of 47.1 years old; in sheep production it was 19.5 years old, who mainly produce maize with a yield of two tons per hectare, which is also used to feed their family and the sheep, mainly in the low water months. 95% of the producers herds their sheep around 4.4 hours a day. They sell sheep when there is an economical need, when income resources are needed for the children’s school; or for a family gathering. The main problem which producers face in sheep production is commercialization, because sheep and lamb are not well-paid.

In Mexico there is no model of rural extensionism designed according to the conditions and aspects of the country; only adaptations of extension systems based on models of developed countries such as the United States (USA) have emerged, which have not allowed obtaining the expected results; For this reason, the objective of this work is to identify and analyze the critical points of the operation of the “New Rural Extensionism” program implemented in the state of Michoacán. The extension process of the 2018‑2019 exercise was analyzed, the information was obtained through participant observation, field visits, participatory workshops; and, analysis, discussion and documentary review of the operation of the state component under study. When carrying out the analysis, the three main critical points of the current extension model that af fected the operation of the program in the state were identif ied, which were: inexistence of an adequate evaluation of the impact of the “New Rural Extension” on agricultural production, disarticulation of the universities and research institutes, which generates the absence of methodological support and the absence of an adequate evaluation of the extensionist’s performance. Despite being based on holistic concepts, the ef forts are scattered and disjointed given that the purposes have focused on the number of producers served as a goal and on the producer as a factor adopting the technology under an intervention with a linear approach.