Browsing by Author "Miller, William P."

Now showing 1 - 6 of 6
  • Analysis of land use change and soil erosion in an Andean watershed
    Velásquez, 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 Cotacachi
    Zehetner, 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 Cotacachi
    Zehetner, 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.
  • Pedogenesis of volcanic ash soils in Andean Ecuador
    Zehetner, Franz; Miller, William P.; West, Larry T. (Madison, Wisc.: Soil Science Society of America, 2003)
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    Plant-water relations in an Andean landscape: Modeling the effect of irrigation on upland crop production
    Zehetner, 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.
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    Towards sustainable crop production in Andean communities, Ecuador: An assessment of the soils' nutrient status
    Zehetner, 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.