The study examined the diversity of herbaceous species and growth forms at three N levels, differing in soil moisture intensity, in a dry tropical environment of India. A total of 45 species, distributed in 23 families, were recorded in a two year study. The study indicated that the studied herbaceous communities were spatiotemporally dynamic due to N treatment under varied moisture conditions. Further, the trait categories of year, 2009 were distinct from those of year, 2010 in the NMS (Non-metric Multidimentional Scaling) ordination diagram. In the present study, the N treatments produced a typical humped-back pattern for the diversity of species and growth forms. The study concludes that N accumulation in the soil due course of time reduces the diversity of herbaceous species as well as functional groups and moderate level of N and sufficiently high level of soil moisture are essential for maintenance of high diversity of herbaceous species and functional groups. Under ample soil moisture condition, the N accumulation will reduce the soil pH by the process of acidification and the system could be diversified by the hemicryptophytes.