Evaluation of colemanite as a slow release source of boron fertilizer for potato

Aim: The present study was conducted with an objective to assess the suitability of colemanite (Ca2 B6.O11.5H2O) as a slow release source of boron to potato crop. Methodology: Soil was incubated with boron (1.25 and 2.50 mg kg-1 soil) using borax and colemanite for six weeks. Soil moisture was maintained at 80% field capacity. Soil samples were analyzed weekly for hot-water extractable boron content. Direct and residual effects of borax and colemanite on potato plant growth and boron uptake were studied in pot experiments. Leaf boron concentration was measured by an ICP-OES. Results: In laboratory incubation, although the rate of release of hot water extractable boron from colemanite was slower than borax, it was enough to meet the requirement of potato crop. Application of both the sources of boron increased its content significantly in soil as well as in potato leaves. This study revealed that boron uptake from colemanite was comparable to borax in meeting the boron requirement of potato. Interpretation: Soil incubation and pot experiment studies showed that colemanite is a suitable slow release source of boron fertilizer for potatoes