ABSTRACT
Irrigation management has been established taking into account only soil water potential as the limiting factor for plant growth. The range in soil water content between field capacity and permanent wilting point has been defined as plant available water. However, the soil resistance to root penetration and the soil aeration may also limit crop growth inside the range corresponding to plant available water. The least limiting potential range (LLPR) is a concept that incorporates soil water potentials used to define plant available water as well as soil water potentials in which there is a limitation to crop growth associated to soil resistance to penetration and to soil aeration. The objective of this study was to characterize the LLPR for a Typic Hapludox irrigated by a center pivot system at Guaira-SP, Brazil. The LLPR was determined using the soil water retention curve and the soil resistance curve which were obtained using eighty eight undisturbed cores. The LLPR ranged from 0 to 1.49 MPa and it was negatively related to bulk density (Db). For Db > 1.09 Mg m-3, the soil resistance was the LLPR upper limit whereas soil aeration defined the LLWP lower limit for Db > 1.28 Mg m-3. Available water was equal to LLPR only at Db > 1.09 Mg m-3.
Key words:
available water; bulk density; irrigation management; soil physical quality