AbstractIn this study, the fertility status of the soils in the Cotacachi area, Ecuador, was analysed, and the nutrient limitations in different zones of the areas were identified. The soil fertility parameters studied include: soil organic matter, nitrogen, amorphous materials and phosphorus, cation exchange capacity and potassium and soil acidity and pH. A crop growth model, Decision Support System for Agrotechnology Transfer (DSSAT, version 3.5), was used to examine the long term effects of nitrogen fertilizer application and residue management on maize yields. The volcanic ash soils in the Andean communities around the Cotacachi volcano have the potential to support traditional subsistence agriculture as well as thriving market-oriented production of niche crops, vegetables and fruits. The soils showed significant variations within the study area and, depending on the specific location, different factors may become limiting to crop growth and therefore, deserve special attention. The young soils on the Cuicocha deposits of the southern study area have inherently low potassium contents and would greatly benefit from additions of this nutrient. In high-elevation soils, strong sorption of phosphorus on active amorphous constituents may become yield limiting and necessitate P inputs for optimum crop growth. Nitrogen may be mineralized too slowly to satisfy crop requirements in high-elevation soils, whereas leaching losses may impair adequate N supply in low-elevation soils. The nitrogen status of all soils would greatly benefit from returning residues to the soil after harvest, including leguminous plants in crop rotations, and managing short, improved fallows. Generally, organic nutrient sources seem preferable over inorganic for a number of reasons. The possible avenues for restoring and maintaining soil fertility as the basis of sustainable agricultural production are discussed.