Atributos morfológicos, químicos e físico-hídricos de Neossolos Litólicos e Regolíticos da região do Escudo Cristalino Sul-Riograndense

Abstract

In Rio Grande do Sul the Leptosols and Regosols are shallow soils derived from different source materials. The low effective depth and water storage capacity of these soils gives the Cr horizon singular importance due to its proximity to the soil surface. However, the Leptosols and Regosols are soils of limited agricultural use, data on their genesis, chemistry, physics, mineralogy and morphology are scarce, but obtaining them is important to promote the sustainability and productivity of the areas. In this sense, the aim of the study was to characterize the morphology and water availability of Leptosols and Regosols from the Pinheiro Machado Suite, especially from the saprolithic horizons. For this, seven profiles was sampled from the geomorphological region of the Escudo Sul-RioGrandense, carrying out the morphological description and determining the soil granulometry, the bulk density and soil porosity, the water retention curve and the water available to plants, the soil organic carbon content of the surface and saprolytics horizons. The A horizon depth ranged from 0.07 to 0.28 m in the Leptosols and from 0.20 to 0.54 m in the Regosols and the saprolithic horizons depth varied from 0.22 to 0.50 m in the Leptosols and from 0 .50 to 0.97m in the Regosols. Clay contents in the surface horizons ranged from 77 to 212 g kg-1, while in the saprolitic horizons the variation was from 116 to 440 g kg-1. Roots were found in the fractures of the saprolitic horizons at depths greater than 0.7 m. The highest available water content was found in P2-Ap. The available water in the saprolitic horizons was from 0.11 to 0.29 m³ m-³ and in the surface horizons from 0.10 to 0.31 m³ m-³. Of the seven profiles studied, four of them had the highest available water content in the saprolitic horizons (P3, P4, P5 and P6).