
J. Jpn. Soc. Soil Phys.
+¬:­®
No. +*-, p. +- ,, ,**0

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Ageing Changes of Consolidated Farmland Foundation in Stepped Paddy Field
Chikara OGURA*, Kiyokazu NEMOTO**, Tamotsu FURUYA*, Hiroshi OSARI*, Takahiro SHIONO***and Hajime NARIOKA***** National Research Institute of Agricultural Engineering, ,ῌ+ῌ0 Kannondai, Tsukuba,
Ibaraki -*/ῌ20*3, Japan** Shirakawa-Omotegou Enviromental Network, +ῌ/ Omotegou-Horinouchi Shirakawa,
Fukushima 30+ῌ*.*2, Japan*** National Agricultural Research Center for Kyushu Okinawa Region, ,.,+ Suya, Koshi,
Kumamoto 20+ῌ++3,, Japan**** Graduate School of Bioresources, Mie University, +/11 Kurimamachiya-cho, Tsu,
Mie /+.ῌ2/*1, Japan
Abstract
The project areas to consolidate paddy ﬁelds have been shifting from ﬂat to sloping terrain
since around +32*.

Studies from various aspects on shifting to sloping areas were carried out tosolve the foreseeable problems about such consolidation of paddy ﬁelds.
nical problems occurred while implementing these projects.

However, further tech-For example uneven rice growing

areas appeared in the central areas of paddy lots after consolidation. Areas where rice was
growing unevenly were becoming overlaid with piled surface soil during consolidation works.
The survey revealed the lack of plowsole, and sedimentation of the original surface soil occurredin the same location where uneven rice was growing right after consolidation. The survey also
revealed that the uneven rice ﬁelds remained after +/ years of consolidation, and that bearing
capacity of foundation soil around the central part of a paddy lot was lower than the periphery.
The consolidations have long-term e#ects on the conditions of soil and rice cultivation. Therefore, it is important to consolidate farmland foundations in order to make farmland adequate forrice production.
Key words : Stepped paddy ﬁeld, Farmland consolidation, Plowsole, Bearing capacity+    MN;</+32* OPQ"RSTU!VWLXYZ[!"#$%&'()\G]^_EH=`a;<D=/ 7 bcdce*+,-./ "+01,234% 567;"RS /0῍ Lfg_ +32, Ohi8(9:;</ 0=> ?@ A? BC<=D+* a j@kl

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after consolidation.

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