Abstract

                                Organic carbon content and alkaline permanganate-oxidizable N (KMnO4-N) are two indices extensively used to assess the available N status of soils. The microdiffusion method proposed by Cornfield is another technique used to estimate the soil available nitrogen and this method has not been so far evaluated for the soils of Tamil Nadu. In the original method, the Conway unit is used for diffusion and absorption of the released ammonia. Since the cost of the Conway unit is more, the original technique has been slightly modified and its performance is evaluated using forty soil samples collected from different parts of Tamil Nadu. Significant correlations of microdiffusion-N with organic carbon and KMnO-N were obtained with r values of 0.777 and 0.688 respectively. The results revealed the suitability of the modified technique for wider use since it is cheaper and can be adopted for reliable estimation of soil available nitrogen.

Key words : Microdiffusion-N, Organic carbon, Available N estimation