Quantification of the pore size distribution of a Rhodic Hapludox under different management systems with X-ray microtomography and computational simulation

Abstract

Agricultural soils are extremely susceptible to changes due to agricultural practices. Conventional tillage (CT), minimum tillage (MT) and no-tillage (NT) are examples of important management systems largely utilized in Brazil, one of the world’s leading producers of coffee, sugar, soybean, corn, and many other agricultural products. Evaluate how these managements disturb the soil structure at the micrometric scale constitutes one of the major challenges for the soil scientists. Due to its potential of producing high-resolution images, X-ray microtomography (μCT) has been increasingly considered as a technique for accurately characterizes three-dimensionally (3D) the soil pore network. In this study, the use of X-ray μCT images associated with a computational algorithm based on the mercury intrusion porosimetry (MIP) was utilized for quantifying changes in the soil structure, induced by different management systems (CT, MT, NT), as compared to the same soil under forest (F). 3D analyses of the pore system were carried out and complemented with information from the soil water retention curve (SWRC) and its first derivative, the water capacity function (WCF). The obtained results showed that the soil under CT and MT presented significant changes in its pore size distribution as compared to F and NT. Results from both methods showed that CT and NT were the managements that promoted major changes in the soil porosity mainly by increasing the percentage of transmission pores (< 500 μm). The obtained results also suggest that the computational algorithm based on MIP, running on 3D images (30 μm of spatial resolution), was valuable to quantify the pore size distribution and their modifications induced by the different management systems.