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Apparent Recovery and Physiological Efficiency of Nitrogen in Sesbania Incorporated before Rice
Author(s) -
Furoc R. E.,
Morris R. A.
Publication year - 1989
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1989.00021962008100050021x
Subject(s) - sesbania , oryza sativa , green manure , nitrogen , agronomy , manure , zoology , chemistry , biology , biochemistry , organic chemistry , gene
When incorporated for lowland rice ( Oryza sativa L.), the agronomic efficiency of green manure N exceeding 100 kg ha −1 is low. Apparent N recovery and physiological efficiency of green manure N, ranging to 200 kg N ha −1 were determined on a fine, mixed, isohyperthermic Aerie Tropaqualf in the Philippines. Sesbania sp. accumulated 100 kg N ha −1 in 48 d and 160 kg N ha −1 in 60 d. Nitrogen uptake (NU, kg N ha −1 ) from green manures flooded during the last 25 d before incorporation was a linear function of incorporated N (NU = 49 + 0.23N). Uptake from green manures that were not flooded diminished as incorporated N increased (NU = 35 + 0.51N – 0.0012N 2 ). The flooding effect was attributed to inhibition of NO − 3 accumulation on submerged control plots. Nitrogen uptake was linearly related to extractable NH + 4 ‐N determined 7 d after green manure incorporation. As N uptake increased, however, physiological efficiency declined. Dry‐season rice recovered only 6% of the green manure N not recovered by wet‐season rice. Because both apparent recovery and physiological efficiency are low, and residual green manure N recovery is minor, the advantage to growing Sesbania sp. for more than 48 d to accumulate N in excess of 100 kg ha −1 is limited.