Evaluation of available nitrogen indices for rice in soils of Mizoram

The nitrogen availability for rice in the soils of Mizoram was evaluated by three soil parameters (Organic carbon, total N and ammoniacal N) and three chemical oxidation (Alkaline permanganate, acid dichromate and hydrogen peroxide) methods. The amount of N extracted by acid dichromate recorded highest values accounting for 50.2% of the total N. Soil NH₄-N and the available N extracted by K₂Cr₂O₇ and alkaline KMnO₄ were highly significantly correlated with percent yield and percent N uptake. The ammoniacal N is a simple, rapid and reliable method and it is adaptable for routine analysis for determining the available N status in rice soils of Mizoram.