Instituto Nicaraguense Of Tecnologia Agropecuaria Inta

Managua, Nicaragua

Instituto Nicaraguense Of Tecnologia Agropecuaria Inta

Managua, Nicaragua
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Douxchamps S.,ETH Zurich | Humbert F.-L.,ETH Zurich | van der Hoek R.,Centro Internacional Of Agricultura Tropical Ciat | Mena M.,Instituto Nicaraguense Of Tecnologia Agropecuaria Inta | And 5 more authors.
Nutrient Cycling in Agroecosystems | Year: 2010

Canavalia brasiliensis (canavalia), a drought tolerant legume, was introduced into the smallholder traditional crop-livestock production system of the Nicaraguan hillsides as green manure to improve soil fertility or as forage during the dry season for improving milk production. Since nitrogen (N) is considered the most limiting nutrient for agricultural production in the target area, the objective of this study was to quantify the soil surface N budgets at plot level in farmers fields over two cropping years for the traditional maize/bean rotation and the alternative maize/canavalia rotation. Mineral fertilizer N, seed N and symbiotically fixed N were summed up as N input to the system. Symbiotic N2 fixation was assessed using the 15N natural abundance method. Nitrogen output was quantified as N export via harvested products. Canavalia derived in average 69% of its N from the atmosphere. The amount of N fixed per hectare varied highly according to the biomass production, which ranged from 0 to 5,700 kg ha-1. When used as green manure, canavalia increased the N balance of the maize/canavalia rotation but had no effect on the N uptake of the following maize crop. When used as forage, it bears the risk of a soil N depletion up to 41 kg N ha-1 unless N would be recycled to the plot by animal manure. Without N mineral fertilizer application, the N budget remains negative even if canavalia was used as green manure. Therefore, the replenishment of soil N stocks by using canavalia may need a few years, during which the application of mineral N fertilizer needs to be maintained to sustain agricultural production. © 2010 Springer Science+Business Media B.V.

Douxchamps S.,ETH Zurich | Frossard E.,ETH Zurich | Uehlinger N.,ETH Zurich | Rao I.,Centro Internacional Of Agricultura Tropical Ciat | And 4 more authors.
Journal of Agricultural Science | Year: 2012

Multipurpose legumes provide a wide range of benefits to smallholder production systems in the tropics. The degree of system improvement after legume introduction depends largely on legume biomass production, which in turn depends on the legumes' adaptation to environmental conditions. For Canavalia brasiliensis (canavalia), an herbaceous legume that has been recently introduced in the Nicaraguan hillsides, different approaches were tested to define the biophysical factors limiting biomass production on-farm, by combining information from topsoil chemical and physical properties, topography and soil profiles. Canavalia was planted in rotation with maize during two successive years on 72 plots distributed over six farms and at contrasting landscape positions. Above-ground biomass production was similar for both years and varied from 448 to 5357 kg/ha, with an average of 2117 kg/ha. Topsoil properties, mainly mineral nitrogen (N; ranging 25-142 mg/kg), total N (Ntot; 415-2967 mg/kg), soil organic carbon (SOC; 3-38 g/kg) and pH (5·3-7·1), significantly affected canavalia biomass production but explained only 0·45 of the variation. Topography alone explained 0·32 of the variation in canavalia biomass production. According to soil profiles descriptions, the best production was obtained on profiles with a root aggregation index close to randomness, i.e. with no major obstacles for root growth. When information from topsoil properties, topography and soil profiles was combined through a stepwise multiple regression, the model explained 0·61 of the variation in canavalia biomass (P < 0·001) and included soil depth (0·5-1·70 m), slope position, amount of clay (19-696 kg/m2) and stones (7-727 kg/m2) in the whole profile, and SOC and N content in the topsoil. The linkages between topsoil properties, topography and soil profiles were further evaluated through a principal component analysis (PCA) to define the best landscape position for canavalia cultivation. The three data sets generated and used in the present study were found to be complementary. The profile description demonstrated that studies documenting heterogeneity in soil fertility should also consider deeper soil layers, especially for deep-rooted plants such as canavalia. The combination of chemical and physical soil properties with soil profile and topographic properties resulted in a holistic understanding of soil fertility heterogeneity and shows that a landscape perspective must be considered when assessing the expected benefits from multipurpose legumes in hillside environments. © Cambridge University Press 2012.

Douxchamps S.,ETH Zurich | Rao I.M.,Centro Internacional Of Agricultura Tropical Ciat | Peters M.,Centro Internacional Of Agricultura Tropical Ciat | van der Hoek R.,Centro Internacional Of Agricultura Tropical Ciat | And 11 more authors.
Agroecology and Sustainable Food Systems | Year: 2014

To support a sustainable increase in agricultural productivity, the multipurpose legume Canavalia brasiliensis was integrated as forage and green manure into the smallholder crop-livestock system of the Nicaraguan hillsides. Through on-farm trials, surveys, and on-station experiments, we investigated the biophysical and socioeconomic tradeoffs in balancing livestock feeding with soil fertility management at the farm level, including farmers' perception. Use as forage increased milk yields while use as green manure increased nutrient cycling efficiency. Short-term net annual income decreased when used as green manure and increased when used as forage. Management options to handle tradeoffs and maximize legume benefits are discussed. Copyright © 2014 Taylor & Francis Group, LLC.

Aragon E.,Instituto Nicaraguense Of Tecnologia Agropecuaria Inta | Rivera C.,Instituto Nicaraguense Of Tecnologia Agropecuaria Inta | Korpelainen H.,University of Helsinki | Rojas A.,Instituto Nicaraguense Of Tecnologia Agropecuaria Inta | And 2 more authors.
Plant Genetic Resources: Characterisation and Utilisation | Year: 2012

A total of 60 farmers' cacao accessions (Theobroma cacao L.) from Nicaragua were investigated using microsatellite markers to reveal their genetic composition and to identify potentially resistant genotypes against the black pod disease caused by Phytophthora palmivora. These accessions were compared with 21 breeders' accessions maintained locally, two Criollo accessions from Costa Rica and two accessions from Ecuador. The analyses showed a low level of differentiation among groups of farmers' accessions (F ST = 0.06) and that six Nicaraguan accessions were genetically closely related to the two Criollo accessions used as a reference. In addition, seven distinct genotypes were found to have allelic composition that may indicate linkage to resistance alleles, thus being potential parental lines in future breeding programmes. © NIAB 2012.

Tijerino A.,University of Helsinki | Tijerino A.,Instituto Nicaraguense Of Tecnologia Agropecuaria Inta | Korpelainen H.,University of Helsinki
Trees - Structure and Function | Year: 2014

Key message We conducted molecular characterization of Nicaraguan Pinus tecunumanii populations using microsatellite markers. Populations possess considerable genetic variation but there are risks associated with inbreeding and population fragmentation. Abstract We carried out a molecular characterization of three natural populations of Pinus tecunumanii using nine microsatellite markers. All studied populations occur in Nicaragua, where the species has declined primarily due to human-influenced factors. The results showed that there is a high amount of genetic variation in populations (expected heterozygosities 0.775–0.841), populations do not show significant differentiation (mean FST 0.0073), apparently due to frequent gene flow or a more continuous distribution and homogenous genetic composition in the past, and inbreeding is common in all populations (FIS 0.705–0.780). The Structure analysis revealed that there is no evident clustering pattern among P. tecunumanii individuals. Although all studied populations possess a considerable amount of genetic variation, risks associated with inbreeding and population fragmentation should be acknowledged and a conservation strategy developed to safeguard the genetic resources of P. tecunumanii. © Springer-Verlag Berlin Heidelberg 2014.

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