Geoestatística aplicada no desenvolvimento de diagramas ternários para a estimativa do conteúdo de água e qualidade física de solos tropicais e subtropicais do Brasil

Abstract

The South, Midwest, Southeast and part of the Northeast are responsible for more than 70% of Brazilian agricultural production. Many of these areas are irrigated by sprinkling and intensively cultivated, which may lead to a decrease in the structural quality of these soils. Soil water and texture control a number of these processes, including soil infiltration and drainage, the organic-matter dynamics and the energy balance of the soil-plant system. The spatial variability of physical attributes is a function of pedological formation factors, however, much of this variability can be induced by management practices. It is research attribution to develop soil quality indexes adapted to each ecosystem, as a way of identifying their status and defining critical limits that might suit as indicators for different soils. Thus, the present study had as objectives, which were split into two chapters: (i) assess the physical quality of soils in sprinkling irrigated areas in tropical and subtropical regions from index that indicate soil quality and physical attributes and; (ii) develop pedotransfer ternary diagrams to estimate the soil water content from a geostatistical approach. This study was developed using the physical-hydric database of irrigated areas of the Sistema Irriga®, belonging to the Department of Rural Engineering, of the Federal University of Santa Maria. The database contains approximately 11,200 observations regarding the physical characterization of soils in the states of Rio Grande do Sul (RS), Paraná (PR), Bahia (BA), Mato Grosso (MT), São Paulo (SP), Minas Gerais and, Goiás (GO). The results obtained in this research demonstrate the importance of studies on a macro scale, pertinent to physical soil evaluation, mainly the association between physical attributes and soil physical quality indexes, thus representing a significant advance in these studies. The development of ternary diagrams for estimating soil water retention represented and strengthened the idea about the applicability and extrapolation of local information, to where is a lack of soil water retention data.