STABILIZATION OF SOIL HYDRAULIC PROPERTIES UNDER LONG TERM NO-TILL SYSTEM

LOZANO, LUIS ALBERTO; SORACCO, CARLOS GERMAN; BUDA, V.S.; SARLI, GUILLERMO OLIVERIO; FILGUEIRA, ROBERTO RAUL

REVISTA BRASILEIRA DE CIêNCIA DO SOLO

SOC BRASILEIRA DE CIENCIA DO SOLO

Año: 2014 vol. 38 p. 1281 - 1292

0100-0683

No tillage (NT) area has been increasing continuously in the last few years. Some authors assume that a stabilization of soil physical properties is reached after some years under NT, but some authors discussed it. The objective of this work was to determine the effect of last crop in the sequence (1st year: maize-2nd year: soybean-3rd year: wheat/soybean) on soil pore configuration and hydraulic properties in two different soils (site I: loam; site II: sandy loam) from Argentinean Pampas region under long-term NT treatments, in order to determine if a stabilization is reached independently of the moment in the crop sequence. Additionally, two procedures to evaluate water-conducting macroporosities were compared, and the efficiency of the pedotransfer function ROSETTA to estimate the parameters of the van Genuchten-Mualem (VGM) model in these soils was evaluated. Soil pore configuration and hydraulic properties were not stable and changed during the crop sequence, depending on the last crop, in both sites. For both sites, saturated hydraulic conductivity, K0, water-conducting macroporosity, εma, and flow-weighted mean pore radius, R0ma, increased from the 1st to the 2nd year of the crop sequence, and this was attributed to the creation of water-conducting macropores by the maize roots. The VGM model described adequately the water retention curve (WRC) for these soils, but not the hydraulic conductivity K vs tension (h) curve. ROSETTA function failed in the estimation of these parameters. To summarize, mean values of K0 varied between 0.74 and 3.88 cm/h. In researches about NT effects on soil physical properties, the crop effect must be considered.