Abstract
Field experiments (20 m2 plots) were conducted to compare Azolla and urea as N sources for rice (Oryza sativa L.) in both the wet and dry seasons. Parallel microplot (1 m2) experiments were conducted using 15N. A total of approximately 60 kg N ha-1 was applied as urea, Azolla, or urea plus Azolla. Urea or Azolla applied with equal applications of 30 kg N ha-1 at transplanting (T) and at maximum tillering (MT) were equally effective for increasing rice grain yields in both seasons. Urea at 30 kg N ha-1 at T and Azolla 30 kg N ha-1 at MT was also equally effective. Urea applied by the locally recommended best split (40 kg at T and 20 kg at MT) gave a higher yield in the wet season, but an equal yield in the dry season. The average yield increase was 23% in the wet season, and 95% in the dry season. The proportion of the N taken up by the rice plants which was derived from urea (%NdfU) or Azolla (%NdfAz) was essentially identical for the treatments receiving the same N split. Recovery of 15N in the grain plus straw was also very similar. Positive yield responses to residual N were observed in the succeeding rice crop following both the wet and dry seasons, but the increases were not always statistically significant. Recovery of residual 15N ranged from 5.5 to 8.9% for both crops in succeeding seasons. Residual recovery from the urea applications was significantly higher than from Azolla in the crop succeeding the dry season crop. Azolla was equally effective as urea as an N source for rice production on a per kg N basis.
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References
Cao Z H, DeDatta S K and Fillery I R P 1984 Effect of placement methods on floodwater properties and recovery of applied nitrogen (15N labeled urea) in wetland rice. Soil Sci. Soc. Am. J. 48, 196–203.
Cao Z H, DeDatta S K and Fillery I R P 1984 Nitrogen-15 balance and residual effects of urea-N in wetland rice fields as affected by deep placement techniques. Soil Sci. Soc. Am. J. 48, 203–208.
Craswell E T and Godwin D C 1984 The efficiency of nitrogen fertilizers applied to cereals in different climates. In Advances in Plant Nutrition. Eds. P B Tinker and A Lauchli. pp 1–55. Prager Scientific, New York.
Eskew D L 1987 Use of 15N in N2 fixation and N cycling studies of Azolla. In Azolla Utilization. Proceedings of the Workshop on Azolla Use. pp 233–239. International Rice Research Institute. PO Box 933. Manila, Philippines.
Eskew D L and Kovacs G T 1989 Isotopic studies on use of Azolla-Anabaena as a green manure for rice. In Proceedings of the International Symposium and Workshop on Nitrogen Fixation Associated with Rice Production. Oxford and IBH Publishing, New Delhi. (In press.)
FAO. 1980 Soil and Plant Testing and Analysis. Soils Bulletin 38/1. Rome.
Fiedler R and Proksch G 1975 The determination of nitrogen-15 by emission and mass spectrometry in biochemical analysis: A review. Anal. Chim. Acta 78, 1–62.
Fried M, Soper R J and Broeshart H 1975 15N-labelled single-treatment fertility experiments. Agron. J. 67, 393–396.
Hart P B S, Rayner J H and Jenkinson D S 1986 Influence of pool substitution on the interpretation of fertilizer experiments with 15N. J. Soil Sci. 37, 389–403.
Ito O and Watanabe I 1985 Availability to rice plants of nitrogen fixed by Azolla. Soil Sci. Plant Nutr. 31, 91–104.
IRRI 1988 Sustainable Agriculture: Green Manure in Rice Farming. International Rice Research Institute, PO Box 933, Manila, Philippines.
Jenkinson D S, Fox R H and Rayner J H 1985 Interaction between fertilizer nitrogen and soil nitrogen- the so-called ‘priming’ effect. J. Soil Sci. 36, 425–444.
Kumarasinghe K S, Zapata F, Eskew D L, Arrillaga J L and Danso S K A 1985 Azolla-Anabaena association: 15N substratum labelling technique to assess N2 fixation and its potential as a biofertilizer for rice. In Biological Nitrogen Fixation in Africa. Eds. H Ssali and S O Keya. pp 454–464. Nairobi Rhizobium MIRCEN, Department of Soil Science, University of Nairobi.
Kumarasinghe K S, Zapata F, Kovacs G, Eskew D L and S K ADanso 1986 Evaluation of the availability of Azolla-N and urea-N to rice using 15N. Plant and Soil 90, 293–299.
Liu C C 1979 Use of Azolla in rice production in China. In Nitrogen and Rice. pp 375–394. International Rice Research Institute. PO Box 933, Manila, Philippines.
Manna A B and Singh P K 1988 Effect of different nitrogen sources on growth, acetylene reduction activity of Azolla pinnata and yield of rice. Plant and Soil 107, 165–171.
Sisworo E L, Sisworo W H, Rasjid H, Kadarusman H, Solahuddin S and Partohardjone S 1987 Influence of Azolla on rice growth with and without N fertilizer. Atom Indonesia 13, 24–32.
Swatdee P, Nammuang C, Chaiwanakupt P, Siripaibool C, Chaiwatna B and Luangsirorat S 1986 Isotopic studies of nitrogen fixation, nitrogen cycling in Azolla and blue-green algae. In Biotechnology of Nitrogen Fixation in the Tropics (BIOnifT) Eds. A H Shamsuddin, W M W Othman, MMarziah and JSundram. pp 155–164. Universiti Pertanian Malaysia, Serdang.
Tuan D T and Thuyet T Q 1979 Use of azolla in rice production in Vietnam. In Nitrogen and Rice. pp 395–405. International Rice Research Institute, PO Box 933, Manila, Philippines.
Watanabe I 1987 Summary report of the Azolla program of the International Network in Soil Fertility and Fertilizer Evaluation for Rice. In Azolla Utilization. Proceedings of the Workshop on Azolla Use. pp 197–205. International Rice Research Institute, PO Box 933, Manila, Philippines.
Watanabe I, Ventura W, Mascarina G and Eskew D L 1989 Fate of Azolla spp. and urea nitrogen applied to wetland rice (Oryza sativa L.). Biol. Fertil. Soils 8, 102–110.
Westcott M and Mikkelsen D 1987 Comparison of organic and inorganic nitrogen sources for rice. Agron. J. 79, 937–943.
Yoneyama T, Ladha J and Watanabe I 1987 Nodule bacteroids and Anabaena: Natural 15N enrichment in the legume-Rhizobium and the Azolla-Anabaena symbiotic systems. J. Plant Physiol. 127, 251–259.
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Sisworo, E.L., Eskew, D.L., Sisworo, W.H. et al. Studies on the availability of Azolla N and urea N for rice growth using 15N. Plant Soil 128, 209–220 (1990). https://doi.org/10.1007/BF00011111
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DOI: https://doi.org/10.1007/BF00011111