Division of Soil Science and Agricultural Chemistry, Indian Agricultural Research Institute, New Delhi, 110 012.
Present address:1 NBSS & LVP (ICAR), Regional Centre, IARI Campus, New Delhi, 110 012.
Total N was positively correlated with organic carbon content of soils of different landforms but did not follow consistent pattern of distribution within the profile in majority of the soils due to leaching of N and fluvial characteristics. Mineral N (NH4+, NO3−) accounted for 0.6 to 4.2 per ceot of total N which was dominated by NH4-N and its distribution in the profile varied with profile characteristics and age of landform. Some soils have nearly same available N content despite large variations in organic carbon and total N, which may be attributed to variations in other factors in soils such as C/N ratio of organic matter, texture, mineralogy and bulk density which probably brought about similar N mineralization rates. In alluvial landforms the pattern is not clear but Vertisols containing smectitic clays showed lowest per cent of available N of its total N in comparison to soils of other landforms. The C/N ratio of surface soils varied from 8 to 13.5 and decreased from hills to plains.
Landforms, forms of N, C/N ratio, profile characteristics
