Evaluacion del Intervalo Hídrico Óptimo de un molisol en secuencias de cultivos con diferente nivel de intensificación

Abstract

Current simplification of cropping sequences has increased soil degradation, affecting soil properties related to water availability, O2, and nutrients useful for crop growth. An increase in cropping intensity (CI) (i.e., a higher period of the year with vegetal cover), arises as a useful alternative to improve soil properties. The aim of this work was to evaluate the Least Limiting Water Range (LLWR) in a Mollisol with different CI. Three cropping sequences were analyzed: soybean monoculture [Glycine max (L.) Merr.] (S), wheat (Triticum aestivum L.) / Soybean-maize (Zea mays L.) (W/S-M), and wheat/soybean (W/S) in an Aquic Argiudol of the Tezanos Pinto Series, in Paraná Experimental Station of the National Institute of Agricultural Technology (INTA). In undisturbed soil cores, were determined soil water retention at field capacity (FC) and wilting point (WP). It was calculated the volumetric water content equivalent to a critical soil penetration resistance (PRc) of 2MPa and at air-filled porosity through two methods. Soybean monoculture had less water content at FC and WP, and the lower water saturation at PRc. There were significant differences between cropping sequences in the LLWR at two depth, with a higher reduction in S treatment and higher value in W/S. It was detected a positive relationship between CI and LLWR at 5-8 cm depth, being more closely related using water content at air-filled porosity of 6 kPa. LLWR was a suitable indicator of physical soil properties to differentiate cropping sequences with different CI.