At harvest in 2005, 2006 and 2007, the aboveground biomass
(straw plus grain yields) under the fertilized plots ranged
from 12.8 to 16.2 t dry matter ha−1, values significantly higher
than those under the unfertilized plots (ranging from 10.1 to
12.2 t dry matter ha−1) (Fig. 2). The increases in harvested aboveground
biomass following the N fertilization were 24–40% and
33–49% in the N150 and N250 treatments, respectively, as compared
to N0. Increasing the N fertilization rates from 150 to 250 kg N ha−1
increased the aboveground biomass by 8% on average over the three
rice seasons investigated. These results indicated that N fertilization
stimulated rice growth.