Browsing by Author "Zehetner, Franz"
Now showing 1 - 10 of 10
Results Per Page
Sort Options
- Analysis of land use change and soil erosion in an Andean watershedVelásquez, H.; Zehetner, Franz; Miller, William P. (2001)The analysis of past land use change and the projection of land use change scenarios into the future have been an integral core in the Nanegal study site during Phase I of SANREM Andes. A similar methodology is now being applied to the Cotacachi region in the temperate inter-Andean valley of northern Ecuador. Indigenous populations have lived in this area for thousands of years and have employed farming practices well-suited to the climate and topography of the region during much of that time. Spanish colonization and the introduction of the hacienda system resulted in marked changes in the agricultural context, and the land reform of the 1960s and the arrival of the Green Revolution in the 1970s produced further impacts on land use and land management in the area. Stereo pairs of aerial photographs of the years 1963, 1978, 1993, and 2000 are being interpreted to analyze land use change over the past 40 years. Initial results indicate a marked decline in agricultural production in the high zone (above 3,000 m.a.s.l.) and an increasing urbanization in the low zone (around 2,500 m.a.s.l.). Based on the land use change analysis, soil erosion and sedimentation are estimated over the 40 year study period and its impact on water quality is evaluated using WaTEM (Water and Tillage Erosion Model).
- Describiendo el paisaje: Geología, clima, suelos y hidrología en el área de CotacachiZehetner, Franz; Miller, William P. (2004)Description of geology, climate, soils, and hydrology in the Cotacachi area
- Fertilidad de los suelos y productividad de los cultivos en la zona andina de CotacachiZehetner, Franz; Miller, William P. (2004)Objetivos del estudio presente: analizar el estado de fertilidad de los suelos en el área de Cotacachi; identificar los factores que limitan el crecimiento de cultivos en las diferentes zonas del área; examinar los efectos a largo plazo de la fertilización con nitrógeno, el manejo de residuos y el riego en los rendimientos de maíz.
- Four decades of land use change in the Cotacachi Andes: 1963-2000Zapata Ríos, X.; Rhoades, Robert E.; Segovia, M. C.; Zehetner, Franz (Cambridge, MA: CABI Publishing, 2006)This fourth chapter uses a combination of scientific tools and interview to track changes in land use patterns in Cotacachi over the latter half of the twentieth century. Major trends found in the study include increasing agricultural production across tracts of brushland, the break up of low land haciendas due to agrarian reform, and increasingly mixed forest composition as timber becomes a more important commodity for economic use.
- Pedogenesis of volcanic ash soils in Andean EcuadorZehetner, Franz; Miller, William P.; West, Larry T. (Madison, Wisc.: Soil Science Society of America, 2003)
- Plant-water relations in an Andean landscape: Modeling the effect of irrigation on upland crop productionZehetner, Franz; Miller, William P. (Watkinsville, Ga.: SANREM CRSP, 2003)In the inter-Andean valleys of northern Ecuador, irrigation systems have long been used to minimize drought risk and secure the production of food crops during dry periods. However, not all Andean communities have access to irrigation water. Increasing population pressure has forced many peasant farmers to move higher up the volcanic slopes and cultivate more marginal land under rainfed conditions. In the SANREM CRSP research site of Cotacachi, local community members and officials of the local water authorities (juntas de agua) have been seeking to expand existing irrigation systems to a wider area. University of GeorgiaÕs researchers Franz Zehetner and Bill Miller analyzed the potential benefits to crop production that such expansion could bring about in different zones of the Cotacachi area that currently do not have access to irrigation water. The scientists used crop growth modeling to quantify the improvement of wet-season and dry-season maize production that would occur if irrigation water was available.
- Plant-water relations in an Andean landscape: Modelling the effect of irrigation on upland crop productionZehetner, Franz; Miller, W. P.; Zapata Ríos, X. (Cambridge, MA: CABI Publishing, 2006)Chapter 13 models the potential impact of expanding the availability of irrigation in Cotacachi. While Cotacachi receives enough rain to cultivate a number of crops in the rainy season, during the dry season production is severely limited by the availability of water. Thus the chapter argues that irrigation systems in Cotacachi should be expanded.
- Soil fertility changes, potentials and vulnerabilitiesZehetner, Franz (2004)This presentation reports on a study with the objectives of analyzing the fertility status of the soils in the Cotacachi area, identifying limiting factors in different zones of the area, and examining the long-term effects of nitrogen fertilization and residue management on crop yields
- Toward sustainable crop production in Cotacachi: An assessment of the soils' nutrient statusZehetner, Franz; Miller, W. P. (Cambridge, MA: CABI Publishing, 2006)In Chapter 12, soil nutrients and soil quality in Cotacachi are thoroughly examined to evaluate historic, current, and future capacity for crop production. The Cotacachi soils are composed of volcanic ash, which gives them capacity to support both subsistence and commercially scaled models of agricultural production. However, these soils have been cultivated for over 4000 years, meaning that they must be carefully managed to ensure not to deplete the soil of one nutrient or another. Moreover, the soils vary in quality across Cotacachi, demanding that specific solutions be created to address problems of sustainability and nutrient conservation.
- Towards sustainable crop production in Andean communities, Ecuador: An assessment of the soils' nutrient statusZehetner, Franz; Miller, William P. (Watkinsville, Ga.: SANREM CRSP, 2003)The volcanic ash soils of northern Ecuador have supported agricultural activities for thousands of years; however, at the dawn of a new millennium, in the peasant communities of Cotacachi, where crop yields have been declining over the past decades, the sustainability of agricultural production seems to be threatened. Within the SANREM CRSP, researchers Franz Zehetner and Bill Miller analyzed the fertility status of the soils in the Cotacachi area and identified limiting factors to crop growth in different zones of the area. The researchers used crop growth modeling to examine the long-term effects of nitrogen fertilization and residue management on maize yields, and to identify possible avenues for restoring and maintaining soil fertility as the basis of sustainable agricultural production.