EFFICACY OF CRUSHED ORE COLEMANITE AS BORON FERTILIZER FOR RICE GROWN UNDER CALCAREOUS SOIL CONDITIONS

Boron (b) deficiencies occur over a wider range of soils and crops in the world. different sources of fertilizers are used to supply sufficient amounts of b for healthier plant growth. the effectiveness of crushed ore colemanite as b source for rice crop under flooded calcareous soil was evaluated in a glass house study. we studied the effects of powder colemanite (pc) and granular colemanite (gc) at the rates of 0, 1, 2, and 3 kg b ha^-1 on growth and yield parameters of rice crop. powder colemanite application at 2 and 3 kg b ha^-1 significantly increased plant height, number of tillers and panicles plant^-1, number of grains panicle^-1, weight of 1000 grains and b concentration in grain compared to those observed due to application of 0 and 1 kg b ha^-1. rice crop applied b at 3 kg ha^-1 in the form of pc produced significantly (18% increase over control) higher grain yield than 0 kg b ha^-1 treatment. the effectiveness of pc was higher in terms of yield and yield parameters of rice than the gc, the b source of pc was very effective in supplying b to rice crop, however gc applied pots produced significantly lower yields because of its larger particle size which was the controlling factor in b release from the fertilizer.