Biochar is a carbon-rich organic material, obtained by the thermochemical conversion of biomass in an oxygen-limited environment, used as a soil amendment to stimulate soil fertility and improve soil quality. There is a clear need in developing countries for access to low cost, low technology options for biochar production, for example, top-lit updraft (TLUD) stoves, which are popular and spread worldwide. However, TLUD biochars are inevitably very variable in their properties for a variety of reasons. We present laboratory triplicate tests carried out on TLUD biochars obtained from waste pinewood and a Guadua bamboo. Analyzed properties include specific surface area (A-BET), porosity, skeletal density, hydrophobicity, proximal and elemental composition, cation exchange capacity (CEC), relative liming capacity and pH. SEM images of the bamboo and wood biochars are compared. The biochars were mixed with composted human excreta at 5% and 10% biochar content, and available water content (AWC) was analyzed. Operating temperatures in the TLUD were recorded, showing different behaviors among the feedstocks during the process. Differences in operating temperatures during charring of the bamboo samples seem to have led to differences in A-BET, hydrophobicity and CEC, following unprecedented trends. For the mixtures of the biochars with compost, at 5% biochar no significant differences were observed for AWC. However, in the 10% biochar mixtures, bamboo biochar showed an unexpectedly high AWC. Overall, variations of chemical and physical properties between bamboo biochars were greater, while pinewood biochars showed similar properties, consistent with more homogeneous charring temperatures.

Soil degradation and water stress in Costa Rica challenge the production of highly sensitive crops. This work is aimed at evaluating the physical and chemical changes in sandy loam (SL) and a silt loam (SiL) soil when amended with bamboo biochar while estimating the enhancement of tomato productivity. Biochar, obtained from Guadua Angustifolia bamboo feedstock, was mixed into sieved bulk soil substrate from the topsoil, from Andosol and Umbrisol groups, at application rates of 1, 2.5, and 5% (dry mass). Physicochemical and morphological properties of biochar such as pH, hydrophobicity, scanning electron microscopy images, helium picnometry, specific surface area by the Brunauer–Emmett–Teller (BET) method, CHNS, and ash content were determined. Soil hydrophobicity, acidity, electrical conductivity, cation exchange capacity and water retention, available water content, and air capacity were analyzed for the amended soils. Tomato yield was quantified after a harvest period of two months. The admixture of biochar did not significantly increase soil cation exchange capacity but increased water retention in the range of available water content. Class A (>200 g) tomato yield increased 350% in the SL and 151% in the SiL. Class B (100–200 g) tomato yields increased 27% in the SL but decreased about 30% in the SiL. Tomato yield response seems attributable to variation of water retention capacity, available water content, and air capacity. These results support the use of adapted water management strategies for tomato production based on soil physical changes of biochar.

<p>Se da una idea general sobre el tema de la carbonización de residuos biomásicos, y se describen brevemente dos proyectos en esta área de investigación que en el primer semestre del 2012 se desarrollan en el Tecnológico de Costa Rica (TEC).Ambos proyectos están enfocados en la carbonización de residuos biomásicos del beneficiado del café y se realizan en colaboración con Coopetarrazú. El que dio inicio en el 2011 está dedicado a la carbonización de material seco, y abordará tanto el uso energético como el uso agrícola del biocarbón. El que dio inicio en el 2012 está enfocado en la carbonización hidrotérmica de biomasa presente en las aguamieles.</p>

Objetivos: Divulgar conocimiento científico sobre el hidroarsenicismo en América Latina, y determinar la presencia de arsénico en agua utilizada para consumo humano en lugares de riesgo en Costa Rica, específicamente en la provincia de Cartago, en los cantones de Oreamuno, Central, Paraíso y Alvarado.Métodos: Cuantificación de arsénico en su forma reducida trivalente, mediante generación de hidruros metálicos volátiles por absorción atómica de llama, metodología 7062 de la Agencia de Protección Ambiental de Estados Unidos.Resultados: Ninguna de las muestras analizadas superó el límite máximo permitido por la legislación actual costarricense, de 10 μg/L.Conclusión: A pesar de que las áreas de investigación correspondieron a zonas de alto riesgo por su naturaleza volcánica, la amplia oferta hídrica de los cantones marco del estudio, con áreas de relativa protección circundando las zonas de recarga de las nacientes, hace que la población consuma agua de origen subterráneo, pero de influjo directo superficial, con menor influencia de rocas volcánicas que se encuentran a mayor profundidad.