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

The aim of this study was the spatial identification of the suitability of soils as reactors in the treatment of swine wastewater in the Mexican state of Yucatan, as well as the development of a map with validation procedures. Pedotransfer functions were applied to the existing soils database. A methodological approach was adopted that allowed the spatialization of pedotransfer function data points. A map of the suitability of soil associations as reactors was produced, as well as a map of the level of accuracy of the associations using numerical classification technique, such as discriminant analysis. Soils with the highest suitability indices were found to be Vertisols, Stagnosols, Nitisols and Luvisols. Some 83.9% of the area of Yucatan is marginally suitable for the reception of swine wastewater, 6.5% is moderately suitable, while 6% is suitable. The percentages of the spatial accuracy of the pedotransfer functions range from 62% to 95% with an overall value of 71.5%. The methodological approach proved to be practical, accurate and inexpensive.

In the highlands of Central Mexico a surplus of different forages is observed during the rainy season particularly weeds, which grow in maize fields. Weeds are widely used by farmers to feed dairy cattle. The objective of the present work was to determine the nutritive value of weeds, their content of secondary metabolites, and their effect on in vitro fermentation kinetics when included (at different levels of inclusion) in a diet based on maize straw. The present study was carried out in two regions of the Toluca valley from August to October 2007. A split plot design was used to evaluate the variables associated with the nutritive value and a randomized design was employed to evaluate the content of secondary metabolites in the different weed species. Significant differences (P

The objective of this research was to evaluate the potential yield and fruit quality of 10 beef tomatoes hybrids using a low level technology greenhouse and desertic conditions of Northwest of Sonora. This experiment was done during two years 2005 and 2006 at the Experimental Station of Caborca, INIFAP. The yield reached during both years was of 25.2 kg m-2 but 89.1% of this production was harvested during February to May. The tomatoes hybrids with higher yield were Zuni, Gironda and Charleston with 31.1, 28.2 and 26.7 kg m-2, respectively; while Thomas, Rapsodie, Sedona and Beatrice were the lowest yield with 20.1, 22.4, 23.1 and 24.9 kg m-2, respectively. By other side, the hybrids with better fruit weight in both years were Sedona and Charleston with 211.3 and 209.8 and 194.7 grams fruit-1. Also, there were differences among tomatoes hybrids on physiological disorders susceptibility (fruit cracking and blossom end rot). For this reason, adequate selection of the tomatoes hybrid is a good alternative for increase yield and fruit quality and reduction of physiological disorders.

Data from 289 milk yield records of purebred Holstein, ¾ Holstein ¼ Gyr and ½ Holstein ½ Gyr were used to compare milk production traits of these genotypes in an intensive operation in a subtropical region of northwestern Mexico. The performance traits studied were: 305-d milk yield days (P305), total milk yield per lactation (TMY), average daily milk production (DMP); lactation length (LL), peak milk yield (PM) and day of peak milk. Higher (P<0.05) P305 averages were observed for purebred Holsteins (5417 ± 96 kg) than ¾H ¼G (4807 ± 131kg) and ½H ½G (4541 ± 92 kg). The shortest lactations were observed for ½H ¼G animals (288 ± 2.0 d) whereas the longest lactations were observed for purebred Holstein (303 ± 2.1d). The highest 305-d milk yield was observed in cows calving in January (5283 ± 1090 kg), whereas the lowest milk yield occurred with calvings in June (3989 ± 896 kg). These results indicate that, under intensive management in a subtropical setting, purebred Holstein performed better than crossbred animals, in terms of milk yield. However, in this subtropical environment reproductive performance of purebred Holstein cows is very poor; thus, this study emphasizes the importance of crossbreeding Holstein x Gyr cattle to produce cows that are more adapted to the hot-humid environmental conditions of the region. These results also showed the drastic impact of heat stress during the summer months on the milk yield of these cows.

 The effect of organic management can influence positively the edaphic properties. The aim of this study was to evaluate the degree of organic carbon oxidation and the soil aggregation indexes in areas under organic management and different plant covers. The selected systems were: conventional tillage (corn - CT), no-tillage (eggplant – NT), passion fruit - Desmodium sp intercrops, fig cultivation, agroforestry system (AFS) and a secondary forest area. The soil samples were collected at 0-5 and 5-10 cm depths. The total organic carbon (TOC) was quantified and separated into four fractions (F1, F2, F3 and F4) with decreasing degrees of oxidation, by the use of increasing quantities of sulfuric acid. Aggregate stability was determined by wet sieving, using the indices of mean weight diameter (MWD), geometric mean diameter (GMD) and sensitivity index (SI). The area under corn cultivation presented the lowest TOC concentrations and aggregation indices, in the two depths evaluated. The areas under eggplant and fig presented the highest TOC concentrations at the 0-5 cm depth, and the highest MWD at the 5-10 cm depth. There were SI values above 1 in the areas under fig and passion fruit. In general, the F1 fraction represented the largest proportion of TOC in all areas and in the two depths evaluated. The AFS presented the lowest proportions of TOC in the four fractions (0-5 cm). The area under eggplant (0-5 cm) presented the highest carbon concentrations in the F1, F2 and F3 fractions. However, at the 5-10 cm depth, this behavior was observed in the area under corn, except for the F1 fraction. The results indicate that the management adopted in the area under corn did not favor soil aggregation and TOC. In the other areas, the SI determined indicates that the tillage practices associated to plant cover, in organic systems, preserved soil aggregation when compared to the forest area, at the 0-5 cm depth. The oxidizable carbon concentrations were influenced by the management systems adopted, with higher values in the areas where more plant residues were added to the soil.

The objective of the present study was to determine the chemical composition and in vitro gas production of different legume and wild arboreal pods. Seven seeds of legume browse species, Mexican calabash (Crescentia alata), esculent leadtree (Leucaena esculenta), guamuchil (Phitecellobium dulce), bastard cedar (Guazuma ulmifolia), needle bush (Acacia farnesiana), mimosa (Mimosa sp.) and elephant ear tree (Enterolobium cyclocarpum). Were evaluated for their chemical composition (g/kg DM) and in vitro gas production pattern. Crude Protein was higher for L. esculenta (220) and lower for G. ulmifolia (70). Neutral and acid detergent fiber were higher for G. ulmifolia (687 and 554) and lower for A. farnesiana (267 and 176). Lignin was higher for Mimosa sp. (219) and lower for P. dulce (81). Total gas production (ml gas/g DM) of P. dulce (187) and E. cyclocarpum (164) were higher (P

The objective of this study was to evaluate the precision of an equation developed to estimate the dry matter digestibility (DMD) of alfalfa (Medicago sativa) when used on the tropical legume Clitoria (Clitora ternatea). Acid detergent fiber from Clitoria was determined and its DMD estimated using the equation: %DMD = 88.9 - (0.779 x %ADF), and subsequently in situ and in vitro degradability (DMDE) of the mentioned legume was determined. Mathematical, in situ and in vitro estimates were compared by ANOVA as a completely randomized design and precision of the equation as DMDE estimator of Clitoria hay was determined if P>0.05. Mathematical DMD estimates were not different (P>0.05) to those obtained by in vitro method, and both were significantly different (P<0.05) and lower than in situ estimates. It can be concluded that the equation initially developed to estimate the DMD of alfalfa was a closer estimator of in vitro DMDE of Clitoria, whereas underestimated the in situ parameter by 8.6%.

Shorea robusta Gaertn.f. oleoresin (gum) extracts were used against the skin allergies, diarrhea, dysentery, astringency and is wide spread in different parts of Eastern Ghats of Southern Peninsular India. The objective of the present study was to evaluate the antimicrobial and phytochemical activity of resin extract against pathogenic microorganisms. Successive petroleum ether, methanol, benzene and aqueous extracts of Shorea robusta resin were tested for their phytochemical constituents, antibacterial and antifungal activity. The aqueous and methanolic extracts were found to be most effective against most of the tested organisms. The results confirmed the potency of this plant in the indigenous systems of medicine.

Desde el inicio de la agricultura, hace aproximadamente diez mil años, la humanidad se ha beneficiado de sus productos al satisfacer, con ellos, sus necesidades de alimentación y comercializarlos. Los sistemas de producción agrícola son más organizados y productivos, como resultado del mayor conocimiento sobre agricultura. Sin embargo, la especialización dentro de la agronomía ha propiciado en algunos casos la implementación de innovaciones técnicas que soslayan elementos clave de los sistemas de producción, como los aspectos sociales, culturales, climáticos, o las propiedades físicas, químicas y biológicas del suelo, originando el fracaso en la práctica. El uso de los diferentes tipos de modelos dentro de la agricultura ha surgido como una alternativa de planificación e investigación, dado que pueden utilizarse para predecir el comportamiento de una planta o animal con diferentes manejos, las características del suelo, la interacción entre diferentes cultivos, y el comportamiento de sistemas de producción con interacción de ganado y cultivos. Actualmente se ha incorporado el efecto de políticas agrícolas, racionalidad de los productores, características del mercado y aspectos ambientales. Desde el enfoque de los agroecosistemas estos modelos se han usado para simular la sustentabilidad, bajo una visión holística y sistémica. Otra evolución importante ha sido considerar al productor como un sujeto que participa en la modelación y no como un componente más del sistema a modelarse, en el denominado modelaje participativo. Por lo tanto, el objetivo del presente documento es analizar los distintos enfoques de la aplicación de los modelos para el estudio y planificación agrícola, y sus retos.