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A15N tracer study to compare nitrogen supply by Azolla and ammonium sulphate to IR8 rice plants grown under flooded conditions

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A pot experiment was carried out using a Bangladesh sandy loam paddy soil of pH 6.9 to compare the rates at which nitrogen from Azolla and ammonium sulphate was available to a high yielding rice variety, IR8, grown for 60 days in pots with 4 cm standing flood water.15N tracer studies confirm that nitrogen from ammonium sulphate was more available to the rice plants than from Azolla. An application of 6, 9 and 18 mg N of Azolla pot−1 (each pot contained 250 g soil) increased shoot dry matter yields by 13, 29 and 49% for an uptake of 19, 36 and 85% more nitrogen; the corresponding increases on using ammonium sulphate were 33, 54 and 114% for an increased uptake of 57, 90 and 177% more nitrogen, respectively. About 34% of applied15N of Azolla was taken up by the rice plants in 60 days but 61% of15N of the ammonium sulphate was absorbed during this period. About 45% of the Azolla-N was released in 60 days, 55% remained in the soils as undecomposed material and 11% was lost as gas. The gaseous loss of15N from ammonium sulphate was 14%; 25% remained in the soils.

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  1. 1

    Bremner J M 1965 Isotope ratio analysis of nitrogen in N-15 tracer investigations.In Methods of Soil Analysis, part 2 (C A Black, Ed.) pp. 1256–1286. Am. Soc. Agron., Madison, Wis.

  2. 2

    Bremner J M and Edwards A P 1965 Determination and isotope ratio analysis of different forms of nitrogen in soils. 1 Apparatus and procedure for distillation and determination of ammonium. Soil Sci. Soc. Am. Proc. 29, 504–507.

  3. 3

    Lumpkin T A and Plucknett D L 1980 Azolla: Botany, physiology and use as a green manure. Econ. Bot. 34, 111–153.

  4. 4

    Mian M H and Stewart W D P 1983 A study on the availability of biologically fixed atmospheric dinotrogen by Azolla-Anabaena complex to the flooded rice crops.In Proceedings of First Intern. Workshop on Practical Application of Azolla for Rice Production. Eds. W S Silver and E C Schroder. pp 168–175. Martinus Nijhoff/Dr W. Junk, The Netherlands.

  5. 5

    Peters G A and Mayne B C 1974 The Azolla-Anabaena azollae relationship. I. Initial characterization of the association. Pl. Physiol. 53, 813–819.

  6. 6

    Rains D W and Talley S N 1979 Uses of Azolla in North America.In Nitrogen and Rice, pp. 419–431, IRRI, Los Banos, Laguna, Philippines.

  7. 7

    Shi S L, Cheng L L, Lin H H, Shu C L and Wen C H 1978 Effect of Azllla on the fertility of paddy soils. Acta Pedologica Sinica 15, 54–59.

  8. 8

    Talley S N and Rains D W 1980Azolla filiculoides Lam. as a fallow-season green manure for rice in a temperate climate. Agron. J. 72, 11–18.

  9. 9

    Watanabe I, Espinas C R, Berja N S and Alimagno B V 1977 Utilization of the Azolla-Anabaena complex as a nitrogen fertilizer for rice. IRRI Res. Paper Series 11.

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Mian, M.H., Stewart, W.D.P. A15N tracer study to compare nitrogen supply by Azolla and ammonium sulphate to IR8 rice plants grown under flooded conditions. Plant Soil 83, 371–379 (1985).

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Key words

  • Ammonium sulphate
  • Azolla
  • Flooded soils
  • 15N tracer
  • Nitrogen uptake
  • Rice