When do rice terraces become rice terraces?

  • Yasushi MoriEmail author
  • Masaya Sasaki
  • Eisei Morioka
  • Kumiko Tsujimoto


Rice terraces located on sloped hills in mountainous areas are sometimes abandoned because of lack of labor and difficulties associated with cultivation. Recently, rice terraces also have been re-evaluated from the perspectives of water conservation or flood control. As a consequence, restoration has been conducted in many locations. In this study, we conducted field research on rice terraces in Okayama in order to determine when rice terraces become stable as rice terraces. Soil samples were obtained from depths of 0, 10, and 30 cm in abandoned fields and rice terraces restored in 2015, 2016, and 2017. The results showed that total carbon was the highest in abandoned fields and gradually decreased in the 2017-restored fields, followed by that in the 2016-restored fields. Particle analysis, particularly of surface soil, showed that the sand fraction decreased in order of abandoned fields, 2017-restored fields, and 2016-restored fields. We established that recently restored rice terraces have similar properties to those located on mountain hills, including few fine particles and high organic matter content in the surface soils. If the surface soil was cultivated and mixed with deeper soils, then the clay and silt content would gradually increase with time. Cone penetrometer analysis revealed that there was no clear evidence of a hard pan in the abandoned field and the 2017-restored field. In contrast, a hard pan had begun to develop in the 2016-restored fields and that it had become well established in the 2015-restored fields. Collectively, our findings indicate that although all rice terraces have a superficially similar appearance, recently recovered fields tend to have properties comparable to the properties of those located on mountain hills. These properties gradually change in the 2–3 years following restoration with the subsequent development of a well-established hard pan. We conclude that even rice terraces that have been abandoned for more than 30 years can develop clear properties of rice terraces within 3 years after restoration.


Rice terrace Abandoned agricultural field Soil organic matter Hard pan Restoration 



This work was partially supported by The Japan Society for the Promotion of Science, NEXT program (GS021, 2011–2014), KAKENHI(B) (26292127, 2014–2016), KAKENHI(B) (17H04484, 2017–2019), and KAKENHI(A) (17H01496, 2017–2020). We are also grateful to the local government, organizers, and people in areas M and U who permitted us to conduct this research.


  1. Arai M, Minamiya Y, Tsuzura H, Watanabe Y, Yagioka A, Kaneko N (2014) Changes in water stable aggregate and soil carbon accumulation in a no-tillage with weed mulch management site after conversion from conventional management practices. Geoderma 221–222:50–60CrossRefGoogle Scholar
  2. Lindsay WL (1979) Chemical equilibrium in soils. Wiley, New YorkGoogle Scholar
  3. Miyamoto T, Kawahara M, Mori Y, Somura H, Ide J, Takahashi E, Yone M, Suetsugu A (2013) Evaluation of management practices in forest soil environments using a multi-frequency electromagnetic sounding system. J Jpn Soc Soil Phys 124:17–24Google Scholar
  4. Nakajima M (1997) Conservation and the current state of the rice terraces. Geography 105(5):547–568CrossRefGoogle Scholar
  5. Nakajima, M. (2017) Guide for rice terraces. IenohikariGoogle Scholar
  6. Rice Terrace Research Association (2014) Introduction of rice terraces. Keisou shoboGoogle Scholar
  7. Senga Y (2012) Rural planning studies. Asakura, TokyoGoogle Scholar
  8. Somura H, Takeda I, Mori Y (2009) Influence of puddling procedures on the quality of rice paddy drainage water. Agric Water Manag 96(6):1052–1058CrossRefGoogle Scholar
  9. Statistics first squad Ministry of Agriculture, Forestry and Fisheries (2014) Census of agriculture and forestry. Ministry of Agriculture, Forestry and Fisheries, TokyoGoogle Scholar

Copyright information

© The International Society of Paddy and Water Environment Engineering 2019

Authors and Affiliations

  • Yasushi Mori
    • 1
    Email author
  • Masaya Sasaki
    • 1
  • Eisei Morioka
    • 1
  • Kumiko Tsujimoto
    • 1
  1. 1.Graduate School of Environmental and Life ScienceOkayama UniversityOkayamaJapan

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