PHYSICAL ATTRIBUTES OF YELLOW ULTISOL OF THE SEMIARID NORTHEASTERN IN FUNCTION OF PERIODIC TILLAGE OPERATIONS

Abstract

Preparation procedures affect the physical properties of soil, which over time can lead to a reduction in its quality. Parameters related to soil structure such as state of aggregation, bulk density and porosity are commonly used to infer the physical quality of agricultural soils. Thus, this study aimed to assess the state of aggregation, the flocculation index, bulk density and porosity of Yellow Ultisol in Brazil’s northeastern semiarid region in function of tillage systems and the frequency of operations. The experiment was conducted in an area of the Universidade Federal do Vale do São Francisco - UNIVASF, and treatments consisted of combinations of different types and intensities of tillage operations, which were: no tillage, chisel plow, tandem disc harrow, offset disc harrow with discs of 0.56 m and offset disc harrow with discs of 0.61 m; which received different number of operations (one, two and three). A randomized block design was used with four replications, with treatments arranged in subdivided plots, where the tillage systems make up the plots and number of operations are the subplots. Tilled and undisturbed soil samples were collected to evaluate the stability of soil aggregates, bulk density, porosity and flocculation index. No significant differences were obtained for the parameters Geometric Mean Diameter, mean weighted diameter and aggregate stability index when comparing the tillage systems used. The bulk density and porosity of the soil were not significantly affected by tillage systems or the number of operations.