This study was conducted to establish the elaborate nitrogen fertilization method to enhance N use efficiency in direct-seeded rice on flooded paddy. The nitrogen uptake by rice plants was insignificant until 25 days after seeding, and increased gradually thereafter. During this early growth stage, rice plants absorbed only the
of basal applied N, while the
of N fertilizer remained in the paddy soil. The absorption of basal N by rice plants was almost completed at 46 days after application. Nitrogen top-dressed at 5-leaf stage was well matched to crop nutrient demand, so it could be absorbed so actively in 8days after application. As a result, we could cut down the amount of N fertilizer to
of the basal N level without significant difference in yield. Plant recoveries of fertilizer
applied with different application timings were
for basal,
for 5-leaf stage,
for tillering stage, and
for panicle initiation stage, respectively. When urea was applied with nitrogen fertilization practice based on basal incorporation (BN), plant recovery of
at harvest was
, which was originated from
for grain, and
of the fertilizer
remained in the soil, and the rest could be uncounted. Plant recovery of fertilizer
applied with nitrogen fertilization practice based on topdressing at 5-leaf stage (TN), where N rate was reduced by
compared with BN, was
(grain
), and
of the fertilizer
remained in the soil, and the rest could be uncounted. TN showed a higher
recovery than BN because it was to apply N fertilizer at a time to well meet the demand of rice plant direct-seeded on flooded paddy. We concluded that TN would be the nitrogen fertilization method to enhance N use efficiency in direct-seeded rice on flooded paddy.
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