260 Bulletin UASVM Agriculture, 66 (1)/2009 Print ISSN 1843-5246; Electronic ISSN 1843-5386 Effects of Tillage Management on Soil Porosity and Bulk Density on Rape (Brasica Napus) Adriana BALAN, L. RAUS, G. JITAREANU University of Agricultural Sciences and Veterinary Medicine Iasi Aleea M. Sadoveanu 3, 700490 Iasi, Romania Adriana.balan@hoemme.ro Abstract. Soil tillage systems have a major influence on soil physical characteristics. Optimal soil physical conditions for crop rooting are a result of complex interactions between soil structure and oxygen and water supply to plants roots. The experiment has been conducted in the Didactic Station of the University of Agricultural Sciences and Veterinary Medicine of Iasi, Ezareni Farm. The purpose of this experiment was to investigate the influence of three soil tillage systems (a reduced tillage system, a no-tillage system and conventional tillage system) on several physical characteristics of the soil, such as soil bulk density, soil porosity and soil structural stability. Keywords: reduced tillage agriculture, bulk density, total porosity, rape – wheat INTRODUCTION Besides direct effects, soil tillage is responsible for long term residual effects induces into soil, which act on its physical and physic-mechanical characteristics, by modifying them (Jitareanu et al, 2006). No-tillage systems (NT) are becoming increasingly attractive to farmers because they clearly reduce production costs and because they provide feasible soil management with fewer disturbances to soil agroecosystems comparing to conventional tillage systems (CT). Some researchers (Puget and Lal, 2005 and Mollisol Ishaq et al, 2002) observed no significant effect of tillage methods (no-tillage and plow till) on bulk density (BD) and total porosity, but Hasinur Rahman et al (2008) found that CT increased the total porosity of soil, but the macropores (effective pores) decreased in number, stability and continuity compared with no-till soil. This discrepancy could be due to the differences in crop species, soil properties, climatic characteristics and their complex interactions (Rassmussen, 1999). MATERIALS AND METHODS The experiments were carried out at the Didactic Station of the „Ion Ionescu de la Brad” University of Agricultural Sciences and Veterinary Medicine of Iasi, Ezareni Farm, during farming year 2007-2008. The experimental site is located on a chambic chernozem (SRTS-2003, or haplic chernozems after WRB-SR, 1998), with a clay-loamy texture, 6.8 pH units, 3.7 % humus content and a medium level of fertilization. The soil has high clay content (38-43 %) and is difficult to till when soil moisture is close to the wilting point (12.2%). The experimental site has an annual average temperature of 9,40C and precipitation of 587 mm.