Fig. 1. (a) Time course for recovery of ¹⁵N in rice plants from an application of labeled (99% atom ¹⁵N excess) nitrate at () 17 DAT and () 55 DAT at the 5-cm soil depth in the wet season of 2001. Each point is the mean of four replicates and vertical lines indicate standard errors. The curve for 17 DAT is R_c = 0.26[1 – exp(–1.01t_dal)], r² = 0.95 and for 55 DAT is R_c = 0.22[1 – exp (–0.28t_dal)], r² = 0.96. (b) The recovery of ¹⁵N in rice plants at weekly intervals following an application of labeled (99% atom ¹⁵N excess) () nitrate and () urea at 35 DAT, at the 5-cm soil depth in the wet season of 2001. Each point is the mean of four replicates and vertical lines indicate standard errors. The curve for nitrate is R_c = 0.23[1 – exp(–0.27t_dal)], r² = 0.95 and for urea is R_c = 0.58[1 – exp(–0.47t_dal)], r² = 0.80.