Affiliations: Institute of Soil Science, Chinese Academy of
Sciences, Nanjing 210008, China | Land and Environmental Management Group, AgRsearch,
Ruakura Research Centre, East Street, Private Bag 3123 Hamilton, New
Zealand
Abstract: Ammonia volatilization loss and ^{15}N balance were studied in a rice
field at three different stages after urea application in Taihu Lake area with
a micrometeorological technique. Factors such as climate and the
NH_4^+-N concentration in the field floodwater affecting
ammonia loss were also investigated. Results show that the ammonia loss by
volatilization accounted for 18.6%–38.7% of urea applied at different
stages, the greatest loss took place when urea was applied at the tillering
stage, the smallest at the ear bearing stage, and the intermediate loss at the
basal stage. The greatest loss took place within 7 d following the fertilizer
application. Ammonia volatilization losses at three fertilization stages were
significantly correlated with the ammonium concentration in the field
floodwater after the fertilizer was applied. ^{15}N balance experiment indicated
that the use efficiency of urea by rice plants ranged between 24.4% and 28.1%.
At the early stage of rice growth, the fertilizer nitrogen use efficiency was
rather low, only about 12%. The total amount of nitrogen lost from different
fertilization stages in the rice field was 44.1%–54.4%, and the ammonia
volatilization loss was 25.4%–33.3%. Reducing ammonia loss is an
important treatment for improving N use efficiency.
