Fifteen-atmosphere percentage and permanent wilting percentage in some soils of Northeast Brazil

Abstract

The objective of the investigation was to compare data obtained by the fifteen-atmosphere percentage, using the Pressure Membrane Apparatus and the permanent wilting percentage, by a physiological method some soils of Northeast Brazil. These moisture constants were determined in 108 soil samples as follows: 56 of humid region (Litoral and Mata) in 14 profiles of Latossolic, Podzolic and Hydromorphic soils; 52 of less humid and semi-arid region (Agreste and Sertão) in 14 profiles of Podzolic, Hydromorphic, Regosolic, Rego-latossolic, Grumusolic and Aluvial soils. The 15 atmosphere percentage was measured in accordance to the U.S. Dep. Agric., Handbook 60, (U.S. Saline Laboratory Staff, 1954) and the permanent wilting percentage by (Oliveira 1959, 1960). From the results obtained it is concluded that the values for 15 atm. moisture percentage determined by the pressure membrane method, in the soils studied, coincide with the values obtained using a physiological method, and hence, can be substituted for the latter.