Absorption of molecular urea by rice under flooded and non-flooded soil conditions |
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Authors: | Safeena AN Wahid PA Balachandran PV Sachdev MS |
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Institution: | (1) College of Agriculture, Nileshwar, Kerala Agricultural University, Padnakkad, 671 328, Kasaragod District;(2) Radiotracer Laboratory, Kerala Agricultural University, College of Horticulture, Vellanikkara, 680 654, Kerala, India;(3) Nuclear Research Laboratory, Indian Agricultural Research Institute, New Delhi, India |
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Abstract: | A pot experiment was conducted with rice to study the relative absorption of urea in molecular form compared to the other
forms of N produced in soil from the applied urea. A method involving application of 14C-labelled urea and 15N-labelled urea alternately in two splits was used to quantify the absorption of molecular urea and other forms of N formed
from it. Biomass production and N uptake were greater in plants grown under flooded soil conditions than in plants grown under
non-flooded (upland) conditions. Absorption of N by rice increased with increasing rate of urea application up to 250 mg pot−1 and declined thereafter. The absorption of urea from the flooded soil constituted 9.4% of total N uptake from applied N compared
to only 0.2% from the non-flooded. Under submerged conditions, absorption of urea from topdressing was about twice that from
basal application at planting. High water solubility of the fertilizer and better developed rice root system might have enhanced
the absorption of molecular urea by flooded rice, especially from topdressing. Thus, in the flooded rice system, the direct
absorption of molecular urea from topdressing accounted for 6.3% of the total N uptake from added urea. Under upland condition,
it was 0.12%.
This revised version was published online in June 2006 with corrections to the Cover Date. |
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Keywords: | 14C-urea flooded soil molecular urea 15N-urea rice |
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