Boron Characterization and Distribution in Particle-Size Fractions Separated from a Semi-arid Tunisian Soil

Abstract

Boron is essential for crop growth. However, it is needed in very small amounts. The range between boron deficiency and toxicity in plants is quite narrow. These stressing conditions gravely reduce the yield and the quality of many crop species. Therefore, an understanding of the factors and the reactions affecting its availability in soil is necessary. Against this framework, our research aims to determine the available boron status in a semiarid soil of Dour Ismail irrigated perimeter (North Tunisia). The objective was also to investigate B distribution in different particle size fractions throughout the soil profile. For this purpose, one pit was dug in the field plot that had not received any B fertilization. Our results showed that the highest boron amounts were recorded in deep horizons and were greatly affected by organic matters and clay contents. However, the increase in pH level and the high percentage of TCaCO3 significantly diminished the available B contents mainly in surface horizons. The investigation of the depth boron distribution in the different particle-size fractions indicated a considerable contribution of the silt (2–50 µm) fraction (52% of the soil total available B) while the clay ( 50 µm) fractions seem to play a less important role.