The present study aimed at characterizing the main soil types under melon crop in the Apodi Tableland, state of Rio Grande do Norte. This investigation focused on the mineralogical soil features as an attempt to generate information for adequate soil and crop management. Three soil types were selected: Typic Haplocambids, Typic Eutrotorrox and Arenic Kandiustults. The mineralogy of sand, silt and clay fractions was evaluated through X ray diffraction analyses and scanning electron microscopy in complementary, undisturbed samples. The mineralogical composition was similar in the studied profiles; quartz prevailed in the sand and silt fractions, while the clay fraction consisted predominantly of kaolinite. Profile 1 (CXve), compared with the other two profiles, was the least developed according to the pedogenetic scale. The degree of profile development was almost the same in the profiles 2 (LVAe) and 3 (PVd), although profile 2 was slightly more developed. The fact that profile 1 (CXve) showed chemical properties of a very young soil in contrast with the mineralogy of a well developed soil, demonstrates an incoherence between the two soil attributes and the stage of soil development. Considering the semi-arid conditions of the sites from where the soil samples were collected, the predominance of kaolinite in the clay fraction suggestes that the soils had been formed under climatic conditions distinct than the present. Former conditions were probably more humid, or the soils developed from pre-weathered parent material.
mineralogy; Apodi Tableland; Cucumis melo L
