CHARACTERIZATION OF YELLOW LATOSOLS (OXISOLS) OF SERRA DO QUILOMBO, IN PIAUÍ STATE SAVANNA WOODLANDS - BRAZIL

ABSTRACT The savanna woodlands of Piauí state has great economic importance since it is an area for agricultural expansion, being the fourth most important of Brazil and the first from Brazilian Northeastern. The area accounts for 5.9% of the Brazilian savanna woodlands and 36.9% of the Northeastern savanna, covering 46% of the Piauí state area, in a total of 11.5 million hectares. The goal of this research was to study pedoenvironments of Serra do Quilombo region, which is in Piauí state savanna, as well as identifying existing soil classes, according to the Brazilian System of Soil Classification - SiBCS. Soil identification consisted in characterizing soil profiles along a transect, assessing in-field conditions and collecting soil samples, in areas of native vegetation. The samples were gathered from three distinct points, being two at the edges and one at the center of the plateau. Soil analyses were carried out with samples collected from each horizon through trench digging up to a 2-m depth. Morphological, physical, chemical and mineralogical characterizations were performed for each soil profile, along with an evaluation of the effect of pedogenic factors on their formation and development. All soils under study were formed with source materials of the same geological formation; however, each rock has a distinct contribution to the process, involving sandstones and shales. The characteristics observed in the soil from Serra do Quilombo have no difference from the pattern found in the Brazilian plateaus, and soil profiles were classified as dystrophic clayey Yellow Latosols (Oxisols), according to the SiBCS.

摘要 皮奥伊州的稀树草原林地具有显著经济价值，作为农业扩张的核心区域，其规模位列巴西第四、巴西东北部首位。该区域占巴西稀树草原林地总面积的5.9%，占东北部稀树草原总面积的36.9%，覆盖皮奥伊州46%的国土面积，总面积达1150万公顷。本研究旨在对皮奥伊州稀树草原内的塞拉杜奎隆博（Serra do Quilombo）区域的土壤环境开展研究，并依据巴西土壤分类系统（SiBCS）识别该区域现存的土壤类型。土壤识别工作通过沿样带布设土壤剖面、评估原生植被覆盖区域的野外条件并采集土壤样品完成。样品采集自三个不同点位，其中两个位于高原边缘，一个位于高原中心。研究通过开挖深度达2米的探槽，采集各发生层的土壤样品开展分析。对每个土壤剖面开展形态学、物理学、化学及矿物学特征表征，并评估成土因素对土壤形成与发育的影响。本研究涉及的所有供试土壤均形成于同一地质构造的母质，但砂岩与页岩等不同岩性对成土过程的贡献存在显著差异。塞拉杜奎隆博区域土壤的特征与巴西高原的典型土壤模式并无显著差异，依据巴西土壤分类系统（SiBCS），供试土壤剖面均被划分为瘠态黏质黄色砖红壤（Oxisols）。