Boron in Soils

2 Abstract: Boron (B) deficiency frequency is increasing in rainfed systems and hence the need to diagnose the deficiency. Colorimetric methods are still widely used in soil testing laboratories in India for measuring B. Little information is available on the comparative evaluation of the colorimetric and inductively coupled plasma (ICP) methods for determining extractable B in soils. We describe results on the comparative evaluation of these methods for measuring extractable B in 57 soil samples with pH ranging from 5.0 to 9.5. There was a significant correlation between B values determined by the two methods and the correlation coefficient was higher for soil samples with pH in the neutral to alkaline range. Interaction between soil samples and methods (ICP or colorimetric) was significant except for soil samples in the pH range of 8.0 to 9.5. Precision for