SOIL CHARACTERIZATION OF PINEAPPLE PRODUCING REGIONS OF MEXICO

About 95% of the soils on which pineapple is cropped in Mexico are located in the states of Veracruz, Oaxaca and Tabasco. The objective of this study was to characterize the soils of the Low-Papaloapan basin region, where 74% of the total pineapple planted in Mexico is located. According to the FAO classification system, these soils belong to the orders distric and umbric Cambisols; and the ortic, plintic and humic Acrisols. These soils have developed from alluvial deposits in the Pleistocene under a sub-humid tropical climate, within a pluvial and thermal regime that oscillates from the ustic to the isohyperthermic ustic. The topography is slightly hilly with slopes of less than 10%. Except for the Cambisoles umbrics that can have up to 40% of clays, the remainder is characterized for its soft sandy texture (from 59 to 84% of sand and from 7 to 19% of clay). These soils exhibit a marked lack of structure and poor capacity to retain humidity. Some of their main chemical characteristics are: low organic matter content (1-2%), absent problems of salinity (0.06-0.5dSm m^-1); pH of 3.6-6.7 (H₂0, 1:2) but low content of interchangeable aluminum (<1.0 meq/100 g of soil) and a maximum capacity of 0.057-0.176 mg/g of P. Except for areas that have been cultivated for a long time with pineapple and that exhibit a relatively high accumulation of phosphates in the arable layer, most of the soils are poor (1- 60ppm) in their content of phosphorus (Bray 1) and extremely poor in changeable bases to a point that they present values of CIC not greater than 19.8 meq/100 g of soil. These characteristics determine the need for using high quantities of fertilizers and soil improvers to maintain a sustainable productivity. Regression analyses found that soil pH could be used as a trusted indicator of phosphorus performance as well as of bases and interchangeable acidity.