Prediction of nitrogen availability based on soil organic carbon in commercial mulberry vegetation of Eastern India

Appropriate quantification of nitrogen availability in soil is the prerequisite for proper implementation of soil-test based fertilizer-application scheme. However, most of the soil testing laboratories use soil organic carbon level to suggest fertilizer dose for nitrogen; hence, the present study has been initiated to develop prediction equation for estimating available nitrogen content of soil from its organic carbon content to facilitate the implementation of soil test based on nitrogen fertilizer application in mulberry garden. A total of 300 soil samples comprising 100 locations from each of Malda, Murshidabad and Birbhum districts have been analyzed for estimation of organic carbon as well as corresponding available nitrogen content. Analytical data was further subjected to regression analysis and district wise working equations were developed to predict nitrogen availability in soil from its organic carbon content. All the equations registered quite higher R2 values, significant at 1% level and thus, considered viable to predict nitrogen availability in soil. Moreover, comparison between predicted and observed values of available nitrogen content in some selected soil samples of each of the districts was done to ascertain accuracy of these equations. The accuracy was found reasonable in terms of ±10% variation and thus, the developed equations are competent enough to predict nitrogen availability in soil under mulberry vegetation of the districts under investigation.   Key words: Available nitrogen, mulberry, organic carbon, prediction, soil-test.