Porosity characterization of Argiudolls under different management systems in the Argentine Flat Pampa

Abstract

Soil pore network characteristics are influenced by management and tillage practices. The objective of this work was to verify if the simultaneous use of the information obtained from tension infiltrometers and water release curves contribute to a better understanding of the impacts of different long-term management systems on the pore space of agricultural soils. The study was carried out on the Flat Pampa in Santa Fe, Argentina, in two types of typical Argiudolls with a silty-loam surface soil texture. The following treatments were evaluated: a) no-till with corn-wheat/soybean rotation (NT-R), and b) conventional tillage with wheat/soybean sequence (CT-S) at Gálvez; and a) no-till with corn-soybean-wheat/soybean rotation (NT-R), and b) no-till with wheat/soybean sequence (NT-S) at Videla. Tension values of 0, 1.5 and 3cm were applied using tension infiltrometers with the aim of obtaining soil hydraulic conductivity measurements (K0, K1.5, and K3), and several hydraulic parameters (pore size, pore number, effective macroporosity, conducting macroporosity (ε(a,b)), water flow and water flow decrease). Undisturbed soil cores were collected to determine water release curves (WRC) and soil bulk density (Db). The total macroporosity (Ma) and pore size frequency curve were determined from the fitted model of the WRC. Macropore connectivity was calculated using ε(a,b) and Ma. In Gálvez, the Db values, K at all tensions, the number of effective pores, the mean pore radius and the effective macroporosity were significantly higher for NT-R. The conducting and total macroporosity values were similar in NT-R and CT-S, but the pores had better continuity in NT-R. In Videla, only K0 and K1.5 showed statistical differences in favor of NT-R. This treatment also had a greater number of effective pores, and higher effective, conducting and total macroporosity values, apart from the overall better pore connectivity. There were no significant differences between the NT-R and CT-S for Db and K3. The evaluated indicators determined that the pore network characteristics are affected not only by tillage system, but also by the crops chosen for the rotation. When used jointly, tension infiltrometers and water release curves can be very useful tools for monitoring the evolution of the soils physical conditions.