The runoff of suspended, substances, nitrogen, and phosphorus by enforced draining during the ploughing season experiments in paddy fields

Yoshihiro Yamada, Akitake Igeta, Sachi Nakashima, Yugo Mito, Takako Ogasahara, Sayaka Wada, Tomohiko Ohno, Atsushi Ueda, Fujio Hyodo, Miho Imada, Shigeo Yachi, Ichiro Tayasu, Syoichi Fukuhara, Takuya Tanaka, Eitaro Wada

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6 Citations (Scopus)

Abstract

The runoff of suspended substances (SS), nitrogen, and phosphorus by enforced draining during the ploughing season was calculated from experiments in two paddy fields. The area of a paddy field was 3000m2. The total fluxes were 33 kg (SS), 85 g (total-N), and 46 g (total-P) in Field A, with a small decrease in water levels (8mm), 110kg (SS), 589 g (total-N), and146 g (total-P) in Field B with a major decrease in water levels (72mm). Furthermore, the nitrogen/ phosphorus ratios (mol ratios) of the waste water by the enforced draining were 4.1 (Field A) and 8.8 (Field B). In comparison with N/P of the phytoplankton (16), it was found that the phosphorus flowed out efficiently with the enforced draining. Increasing the supply of the phosphorus to Lake Biwa is not desirable in view of the current problems of eutrophication. The careless water management of paddy fields was a crucial factor in any plan to improve the water quality of Lake Biwa.

Original languageEnglish
Pages (from-to)105-112
Number of pages8
JournalJapanese Journal of Limnology
Volume67
Issue number2
DOIs
Publication statusPublished - Aug 1 2006

Keywords

  • Enforced draining
  • Lake Biwa
  • Nitrogen
  • Paddy field
  • Phosphorus
  • SS

ASJC Scopus subject areas

  • Aquatic Science
  • Ecology
  • Water Science and Technology

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  • Cite this

    Yamada, Y., Igeta, A., Nakashima, S., Mito, Y., Ogasahara, T., Wada, S., Ohno, T., Ueda, A., Hyodo, F., Imada, M., Yachi, S., Tayasu, I., Fukuhara, S., Tanaka, T., & Wada, E. (2006). The runoff of suspended, substances, nitrogen, and phosphorus by enforced draining during the ploughing season experiments in paddy fields. Japanese Journal of Limnology, 67(2), 105-112. https://doi.org/10.3739/rikusui.67.105