Soil Boron Migration as Influenced by Leaching Rate and Soil Characteristics: A Column Study

ABSTRACT

Soil boron (B) supply is usually used by farmers to correct B deficiency in many crops. The excessive application of this fertilizer may threaten environment components particularly underground water and soil. This study was undertaken to evaluate B migration at different soil characteristics and leaching levels. Three soils were collected from different southwestern Mediterranean areas. Then, three annual leaching rates were tested for each soil: 35 mm, 237 mm, and 565 mm in a sandy soil; 35 mm, 103 mm, and 247 mm in a silty-clay soil; 35 mm, 70 mm, and 140 mm in a clay-calcareous soil. The experiments were conducted in PVC columns filled with 30 cm of the studied soils. 0.5 mg kg⁻¹ of B was applied to the surface of each soil. The results showed that B migration is mainly related to leaching rate and clay content. The soil B losses (y) can be predicted using the regression model: y (mg kg⁻¹) = 0.001a–0.01b+0.14 (adjusted R² = 0.92) where a = leaching rates (mm) and b = soil clay content (%). The B leaching threat is higher on sandy soil compared to other soils. However, soil B accumulation risk seems to occur particularly in silty-clay and clay-calcareous soils. Further, bioavailable B enrichment was recorded only on silty-clay soil.

KEYWORDS:

• Boron
• mobility
• leaching
• soil properties

Acknowledgments

The authors are grateful to the Moroccan Laboratory of Agriculture “LABOMAG” for financial support. We wish to thank Miss Lyousfi N., Dr. Asfers A., and Mr. Labiad M. for their valuable help and cooperation in conducting the experiments.