Reference Curve Numbers and Behavior for Sugarcane on Highly Weathered Tropical Soils

Abstract

This work examines rainfall-runoff behavior and determines the reference curve numbers (CNs) on a highly weathered tropical clayey soil (Oxisol, or “latosol”) in Brazil for three conditions: (1) bare soil; (2) sugarcane with replanting each three years; and (3) near-permanent sugarcane without replanting. It compares findings with U.S. experiences and handbook values. Curve number and runoff behavior changed markedly after the seventh month of growth, and the profound influences of cover are clearly demonstrated. A surprising finding was that though these Oxisols are quite rich in clay, the rainfall-runoff results suggest that they should be classified as Hydrologic Soil Group B.