Fate of Fertilizer-Derived N Applied to Enhance Rice Straw Decomposition in a Paddy Field during the Fallow Season under Cool Temperature Conditions

• Published in: Agriculture (Basel) 2018-04, Vol.8 (4), p.50
• Main Authors: Takakai, Fumiaki, Hirano, Seiya, Harakawa, Yuka, Hatakeyama, Keiko, Yasuda, Kentaro, Sato, Takashi, Kimura, Kazuhiko, Kaneta, Yoshihiro
• Format: Article
• Language: English
• Subjects: 15N; Ammonium; Ammonium sulfate; Cultivation; Decomposition; Fertilizers; Harvesting; Leaching; Nitrification; Nitrogen; paddy soil; Rice; Rice fields; rice growth; Rice straw; rice straw decomposition; Soil fertility; Soil lime; Soils; Straw; Sulfates
• ISSN: 2077-0472; 2077-0472
• DOI: 10.3390/agriculture8040050

A field experiment was conducted to evaluate the fate of nitrogen (N) derived from fertilizer (fertilizer-derived N) applied to a paddy field after rice harvesting to promote rice straw decomposition during the fallow season, and to determine its effect on soil N fertility in northern Japan. A frame containing soil mixed with rice straw and 15N-labeled fertilizer (4.3 g N m−2 ammonium sulfate [AS] or lime-nitrogen [LN]) was placed into a paddy field on a gray lowland soil during the fallow season (October-April), and the following rice-growing season (May-September). Before cultivation (April), the percentages of fertilizer-derived N in soil + straw were higher for LN (55-72%) than for AS (41-63%). At the harvesting stage (September), the percentages of fertilizer-derived N in plants were significantly higher for LN (4.9-6.2%) than for AS (3.4-5.3%), and the percentages in soil were also significantly higher for LN (42-61%) than for AS (31-38%). This could be attributed to the nitrification inhibitory effect of LN and result in the suppression of N losses via leaching. Consequently, fertilizer-derived N could contribute to the maintenance of soil N fertility, and this effect could be higher for LN than AS.