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Cali, Colombia

Hien P.T.T.,Nong Lam University | Preston T.R.,CIPAV | Lam V.,An Giang University | Khang D.N.,Nong Lam University
Livestock Research for Rural Development | Year: 2014

The objective of this study was to determine the effect of co-digestion with vegetable waste on biogas production from excreta from cattle, pigs and humans. There were seven treatments arranged in a completely randomized design with three replicates. The treatments were initial loading rates (DM basis) of vegetable waste (V) supplemented with human (H), cattle (C) or pig (P) excreta. V2H1: 2 parts vegetable waste with 1 part human feces; V2C1: 2 parts vegetable waste with 1 part cow manure; V2P1: 2 parts vegetable waste with 1 part pig manure; V1H2: 1 part vegetable waste with 1 part human feces; V1C2: 1 part vegetable waste with 2 parts cow manure; V1P2:  1 part vegetable waste with 2 parts pig manure. The pH of the contents of the biodigesters, and the gas production, were measured daily until the end of the experiment after 60 days. The content of methane in the gas was measured in samples taken after 14, 21, 28, 35, 42, 49 and 56 days.Gas production over the 60 day period was 5 times higher on the combination of one part vegetable waste and two parts cattle or pig manure, compared with the lowest value on the substrate of vegetable waste alone. However, these results did not reflect the potential gas production from the substrates as there were major differences in the pH of the fermenting substrates over the whole incubation period (higher values on the treatments with cattle and pig manure and lowest value on the vegetable waste as sole substrate). Overall,  there was a negative relationship between the pH of the digesta medium and the average daily gas production. On all substrates the pH dropped rapidly during the first 5 to 7 days of incubation; however,  the extent of the fall was smaller, and the recovery more rapid, when cattle manure was the companion substrate compared with pig manure on which the pH recovered more quickly than with human feces. On the 100% vegetable waste substrate, the drop in pH was more pronounced, and the recovery much slower, the pH not begining to rise until some 50 days after the start of the incubation. The trends for methane content of the gas were similar to those recorded for total gas production, with highest values for substrates richest in manure and lowest values for treatments with higher proportions of vegetable waste. The relative values for pH of the digesta and methane in the gas were positively correlated. Subsequent research with food waste as substrate should be directed to systems of management of the biodigester (ie: ensuring a slow build up of the substrate concentration in the first 14 to 21 days of the incubation) or inclusion of buffering agents such as sodium bicarbonate. © 2014, Fundacion CIPAV. All rights reserved. Source


Castano-Quintana K.,University of Valle | Montoya-Lerma J.,University of Valle | Giraldo-Echeverri C.,CIPAV
Industrial Crops and Products | Year: 2013

Leaf-cutting ants (Formicidae: Myrmicinae) have been considered herbivorous generalists; however, some plant species escape their attack because of the presence of secondary metabolites. The main objective of this study was to determine the insecticide effect of foliage extracts of Tithonia diversifolia on Atta cephalotes workers (Hymenoptera: Myrmicinae) and define the potential application ways and concentrations. Extracts were obtained from fresh and dry T. diversifolia foliage, using ethanol as solvent. The principal metabolic compounds were identified and the extracts in three concentrations (0.5. ml/l, 1.5. ml/l, and 3. ml/l) were applied to the ants in two manners: ingestion and contact. Results showed that crude extract of T. diversifolia was toxic to the ants in all concentrations and methods tested; however, dry extracts applied for contact at 1.5-ml/l concentration produced the most efficient toxic effect to A. cephalotes workers. The study contributes to identifying an environmental sound control strategy for the leaf-cutting ant, A. cephalotes. © 2012. Source


Cubillos A.M.,Pontifical Xavierian University | Vallejo V.E.,Pontifical Xavierian University | Arbeli Z.,Pontifical Xavierian University | Teran W.,Pontifical Xavierian University | And 4 more authors.
European Journal of Soil Biology | Year: 2016

Colombia, as well as many tropical countries, has experienced severe deforestation in the last decades, and millions of acres of native forest areas (F) have been replaced by conventional monoculture pastures (CP), contributing to ecological and soil degradation. In response, multi-canopy intensive silvopastoral systems (ISS), which includes herbs, shrubs and trees, have been developed to provide local fodder sources for livestock while reducing the need for external inputs with a goal to conserve landscapes and improve soil quality. However, there is limited information on the temporal responsiveness of ISS to deliver ecosystem services as reflected in soil microbial properties. Therefore, the objective of this study was to examine the shifts of total and ammonia-oxidizing bacteria (AOB) communities along an ISS chronosequence (ranging from 3 to 15 years since establishment), in comparison to CP and native F and investigate P. juliflora trees as a resource island relative to soil microbial properties. Denaturing gradient gel electrophoresis (DGGE) fingerprints of 16S rRNA gene (total bacteria) as well as amoA gene (ammonia-oxidizing bacteria) (AOB) indicated that soil bacterial communities varied between the land uses, with higher similarities between F and ISS communities, in comparison to CP. The abundance and nitrification potential of ammonia oxidizers were significantly higher in CP and lower in F. In addition, the bacterial communities across ISS chronosequence were more similar between older (ISS-12) and intermediate (ISS-8) systems in comparison with youngest systems (ISS-3). Finally, the canopy of P. juliflora tree did not have an impact on structure of total bacterial community; though, it did have an effect on the structure of AOB communities. Our study suggests that ISS might restore some of the ecosystem services offered by soil microbial communities. © 2015. Source


Calle Z.,CIPAV | Murgueitio E.,CIPAV | Chara J.,CIPAV | Molina C.H.,CIPAV | And 2 more authors.
Journal of Sustainable Forestry | Year: 2013

Silvopastoral systems (SPS) enhance milk and meat production and are instrumental for the productive rehabilitation of degraded lands. Intensive silvopastoral systems (ISPS) combine fodder shrubs planted at high densities (>10,000 plants ha-1), trees and pastures. Scaling-up such systems requires incentives to address financial and knowledge barriers. In Colombia, the strategy for scaling-up SPS has combined five elements. First, participatory research on real farms contributed to optimize SPS in different agroecosystems and strengthened a network of pilot farms open to research and peer-to-peer technology transfer. Second, capacity building, training, and outreach activities spread the principles of SPS among farmers, field workers, researchers, extension workers, and policy makers. Third, pilot projects explored the role of incentives such as Payment for Environmental Services (PES), technical assistance, soft loans and bonus prices, in spreading SPS. Fourth, successful pilot projects were instrumental in influencing the livestock sector as well as the public policy agenda. Fifth, currently, large-scale projects aimed at mainstreaming SPS are applying the lessons learned in order to achieve landscape-scale benefits, enhance climate change adaptation and mitigation, and introduce SPS products to green markets. Recently, innovation networks have contributed to speed up the adaptation of SPS in different environmental and socioeconomic contexts. © 2013 Taylor and Francis Group, LLC. Source


Sudre D.,Montpellier University | Gutierrez-Carbonell E.,CSIC - Aula Dei Experimental Station | Lattanzio G.,CSIC - Aula Dei Experimental Station | Rellan-Alvarez R.,CSIC - Aula Dei Experimental Station | And 15 more authors.
Journal of Experimental Botany | Year: 2013

Iron homeostasis is an important process for flower development and plant fertility. The role of plastids in these processes has been shown to be essential. To document the relationships between plastid iron homeostasis and flower biology further, a global study (transcriptome, proteome, metabolome, and hormone analysis) was performed of Arabidopsis flowers from wild-type and triple atfer1-3-4 ferritin mutant plants grown under iron-sufficient or excess conditions. Some major modifications in specific functional categories were consistently observed at these three omic levels, although no significant overlaps of specific transcripts and proteins were detected. These modifications concerned redox reactions and oxidative stress, as well as amino acid and protein catabolism, this latter point being exemplified by an almost 10-fold increase in urea concentration of atfer1-3-4 flowers from plants grown under iron excess conditions. The mutant background caused alterations in Fehaem redox proteins located in membranes and in hormone-responsive proteins. Specific effects of excess Fe in the mutant included further changes in these categories, supporting the idea that the mutant is facing a more intense Fe/redox stress than the wild type. The mutation and/or excess Fe had a strong impact at the membrane level, as denoted by the changes in the transporter and lipid metabolism categories. In spite of the large number of genes and proteins responsive to hormones found to be regulated in this study, changes in the hormonal balance were restricted to cytokinins, especially in the mutant plants grown under Fe excess conditions. © The Author 2013. Source

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