The use of boron isotopes to evaluate boron uptake by rape grown in acid soil treated with boron containing goethite

Abstract

Boron (B), taken up by plants, comes mainly from boron adsorbed by soil constituents, in particular by metal hydrous oxides, organic matter, and edges of clay minerals. The extent and availability of B adsorbed or occluded by soil minerals is unknown due to the lack of a methodology for probing activity of this type of boron. In this study, 10B labeled boron-containing goethites, i.e., goethite with adsorbed B (ad-B-goethite) and occluded B (oc-B-goethite), were added individually to an Ultisol for pot experiments to probe soil B bioavailability. The fraction of soil B extracted from B-containing goethite showed a sigmoidal extraction pattern similar to that of B adsorbed on soil minerals. The rape seedling uptake of B from ad-B-goethite treatment of soil was close to that from soil background (50%), while that from oc-B-goethite treatment of soil was about 66%. The B absorbed from both B-containing goethite and soil was mainly accumulated in the shoot; less than a tenth of the B was accumulated in the root. In summary, the behavior of B in B-containing goethite was generally similar to that of soil B, indicating that B containing goethite can be used to probe migration of B from soil to plant.