Physical conditions of Molisols under soybean cultivation in the Santa Maria River basin, RS, Braz

Abstract

The soybean has been recently introduced in rotation with irrigated rice in southern Brazilian lowlands, promoting many benefits; however, the soil and climate conditions can limit its full development, mainly the soil physical characteristics and drought periods. This study aimed to evaluate the physical conditions of Molisols located in agricultural areas with different tillage systems (conventional tillage and no-tillage) under sprinkler irrigation system (central pivot) in the Santa Maria River basin, Rio Grande do Sul State. Undisturbed and disturbed soil samples were collected in the 0 to 0,1; 0,1 to 0,2 and 0,2 to 0,4 m soil layers to determine attributes as bulk density (Ds), total porosity (Pt), microporosity (Mi), macroporosity (Ma), water-stable aggregates (AEA), mean weight diameter of aggregates (DMP) and variables derivate from the soil water retention curve (CRAS). Soil natural characteristics as hydromorphism and the way they were conducted result in physical conditions classified as restrictive to the full development of soybean in lowlands.