The general N mineralization pattern of various plant residues was that the first N mineralization peak was found in week 2-4, after which there was a general decline of N mineralization until week 16, although some residues exhibited a second peak at week 8 Figure 1, Figure 2 a, b. Some previous incubation studies showed sustained levels of mineral N in soils after they reached the highest levels, e.g., Constantinides and Fownes 1994, and Handayanto et al. 1997.