International comparative study on land consolidation project for sustainable agriculture

今天在日本，种植水稻的农民劳动生产率很低。为了获得充足的农业生产力，实现水稻的可持续生产，必须扩大农民的农场规模，建设规模在几公顷以上的大型稻田。但在日本，这种土地整理工程的实施地区很少，所以大面积的稻田会造成一些技术问题，如排水不良、灌溉时间长、平整条件差等。为了弄清这些问题是否存在，也为了弄清如何在日本实现大面积稻田，本文对美国、澳大利亚和日本的大面积稻田进行了调查。主要结果如下：1)在美国的加利福尼亚和阿肯色州，农场经理用激光平整土地，种植64ha， 36ha， 32ha的巨大稻田已经有20年了。为了有效排水和灌溉，农民在地块周围疏通了临时沟渠。因此，认为大规模种植水稻，整体上以大面积稻田为宜。在澳大利亚的新南威尔士州，农场管理者也一直在平整他们的稻田。但大多数农场的面积都不是很大，大约在5公顷左右，因为农场规模相对较小，大约在200公顷左右。此外，由于农民轮流使用这些土地种植水稻和其他作物，他们需要一些斜坡来为其他作物排水。(3)在日本，大规模稻田是通过整理租赁土地实现的。对于这种土地整理，用户权利调整方法是有效的。

Today in Japan, labor productivity of rice cropping farmers is low. In order to get sufficient agricultural productivity and realize sustainable paddy rice production, it is necessary to enlarge farmers' farm size and construct large rice paddy plots of more than several hectares in size. But in Japan, there are very few areas where such land consolidation project had been carried out, so huge rice paddy plots are concerned to cause some technical problems such as ill drainage, much more time to irrigate, bad leveling condition and so on. In order to clarify whether there are such problems or not and also to clarify how to realize huge sized-rice paddy plots in Japan, investigation on huge sized-rice paddy plots in USA, Australia and Japan was done. Main results are as follows.1) In California and Arkansas in USA, farm managers have been leveling their land with using laser and making huge rice paddy plots of 64ha, 36ha, 32ha for about twenty years. In order to drain and irrigate effectively, farmers dredged temporary ditch around the plots. So it is considered that huge rice paddy plots are preferable as a whole for large size rice farming.2) In NSW in Australia, farm managers have also been leveling their paddy plots. But most of their sizes are not so much huge, around 5ha, because farm sizes were relatively small, around 200ha. And also because farmers use those plots for paddy and other crops rotationally, they need some slope for drainage for other crops.3) In Japan, large size rice paddy plots were realized by consolidating leased land. For such land consolidation, the method of user-right-adjustment was effective.