Hot-water soluble boron in the “Zona Litoral-Mata” soils of the State of Pernambuco

Abstract

The hot-water soluble boron content of eleven typical soils regarded as the most representative of the area known as the “Zona Litoral—Mata” of the State of Pernambuco Brazil (coast area), was determined by two different extraction methods. Both methods gave results in reasonable agreement. The data obtained showed that the most important agricultural soils of the State, have a soluble boron content ranging between 4.34 and 0.58 ppm in the surface horizon. They can be regarded as having a normal content of available boron. If the critical level of 0.50 ppm of hot-water soluble boron is accepted as the limit for a soil to be regarded as deficient, only one, among the studied soils (corresponding to most of the soils of Barreiros country), is near the boundary of deficiency. All the other soils apparently contain an adequate amount of soluble boron. Although the limits of available boron content between deficiency and excess are narrow, the evidences strongly suggests that toxicity symptoms are unlikely to occur. The hot-water soluble boron was well correlated the soil organic matter, exhibiting a clear tendency to concentrate in the surface horizons. There was also a less pronounced tendency for the soluble boron to concentrate in the horizons richest in clay minerals.