International comparative study on land consolidation project for sustainable agriculture

在日本，水稻种植农民的劳动生产率很低。为了获得足够的农业生产力和实现可持续的水稻生产，有必要扩大农民的农场规模，建设几公顷以上的大稻田。但在日本，实施这种土地整理项目的地区很少，因此，人们担心大面积稻田会带来排水不良、灌溉时间过长、平整条件差等技术问题，为了弄清日本是否存在这些问题，以及如何实现大面积稻田，对美国、澳大利亚和日本的大面积稻田进行了调查。主要研究结果如下：1）在美国的加州和阿肯色州，农场管理者已经用激光平整土地，并制作了64公顷、36公顷、32公顷的大面积稻田。为了有效地排水和灌溉，农民们在地块周围疏浚了临时沟渠。因此，人们认为，大面积稻田总体上更适合大面积水稻种植。2）在澳大利亚的新南威尔士州，农场管理人员也在平整稻田。但大多数农场的规模都不大，大约5公顷，因为农场规模相对较小，大约200公顷。另外，由于稻田与其他作物的轮作，需要一定的坡度来排水。3）在日本，大面积的稻田是通过租赁土地的合并来实现的。对于此类土地整理，使用权调整方法是有效的。

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.