Modified version of a dichromate digestion procedure, earlier found suitabl
e for simultaneous determination of organic carbon (C) and potentially mine
ralizable nitrogen (N) in soils, was evaluated for total N determination in
44 diverse soil samples from the semi-arid region of India. The soils belo
nged to Vertisols and Alfisols and had a wide range in total N contents. Th
e method involves digestion of the soil sample with an acidified dichromate
solution for 30 minutes in a digestion tube in a block digester preheated
to 165 degrees C followed by determination of N in the digest by steam dist
illation procedure. The efficacy of the dichromate procedure for determinin
g total N differed for the two soil types. Excellent correlations were obse
rved between the values of total N obtained by the dichromate procedure (Di
chro-N) and by Kjeldahl method (Kjeldahl-N) for Vertisols (R-2=0.995; n=21)
and Alfisols (R-2=0.952; n=23). The regression equations describing the re
lationships between the two soil types can be used to estimate Kjeldahl-N f
rom Dichro-N. Both Kjeldahl and the proposed acid dichromate methods were f
ound to more precise in determining total N in Vertisols than Alfisols. The
proposed procedure is rapid and simple and can be used for routine total N
determination especially, in soils such as Vertisols. Based on our results
the acid digestion procedure certainly deserves a wider evaluation with a
range of soil types.