Zonificación agroecológica del Coffea arabica en el municipio Atoyac de Álvarez, Guerrero, México

Abstract

Costa Grande, the largest coffee-producing region in the state of Guerrero, is where the lowest yields are obtained at the state level: An average 249 kg per ha, according to Sagarpa et al. (2011). This may be due not only to the low plant density in the area (approximately 1 274 plants per hectare), but also to the lack of chemical fertilization. It is estimated that chemical fertilizers are applied to only 0.2% of the coffee plants, and only 3% of them benefit from the manure added to the soil. With the aim to establish agro-ecological areas for Coffea arabica (i.e., those with the most favorable agricultural conditions and the highest biophysical potential for optimum yields) a territorial survey was carried out in the municipality of Atoyac de Álvarez, Guerrero analyzing geomorphological, hydrothermal and edaphic maps based on gis platforms. Six map sheets at a scale of 1:50 000 (inegi, 2009) were employed so as to cover the entire area of study. On these maps the altitude, inclination, climate (temperature, rainfall) and soil types that were compatible with the agronomic requirements of Coffea Arabica were identified and marked out. Rainfall, temperature and soil type data were obtained from maps at a scale of 1:250 000 (inegi, 2009) transformed from vector to raster formats so as to facilitate automated processing. For the morphometric evaluation of the relief, a digital elevation model was built with measurements at each 20 m so as to obtain an hypsometric gradient of 100 m and the classification of inclination into four classes: 0.1° to 18° (32%), 18.1° to 25° (33-47%), 25.1° to 40° (48-84%), and over 40° (> 84%). Central to the agro-ecological zoning of coffee is the concept of agro-ecological potential, as the set of quantitative and qualitative requirements on the natural environment conducive to the proper development of the coffee plant. The relationships between the different variables and the determination of their potentials, as well as the physical-geographical zoning of Coffea Arabica, depended on the reclassification of selected variables and their spatial analysis based on GIS using the software ILWIS 3.31 with a view to obtaining an integrated natural potential model. Agro-ecological areas with optimal, medium, low and very low potentials for the production of this variety of coffee were defined. Optimal areas are located at moderate-to-weak mountain slopes (1.1° to 18°) with Acrisols (hierarchical key Ah+Bh+Hh/2) in semi-warm climates (18 ° to 22 °C) with a rainfall regime between 1 500 and 2,000 mm and at an altitude between 1,100 and 1 500 m. They extend over an area of 7 163.47 ha. Medium-potential areas cover 28 143.75 ha, low-potential areas 62 130.65 ha, and very-low potential areas 58 411.38 ha. This agro-ecological zoning of Coffea arabica is a valuable technical instrument based on national and international experiences and information on the natural conditions prevalent in the municipality of Atoyac de Alvarez. The updating of a database on geomorphological, climatic and soil conditions will help to devise strategies for the achievement of higher crop yields. This approach and methodology can be implemented in any geographical setting with the necessary map scales adjustments and evaluation of the local agro-ecological features. It has the potential to contribute to government and business initiatives alike for the planning and management of coffee areas of their promotion.