Former and Present Cropping Patterns in the Mekong Delta

抄録

In a previous paper, I proposed five landform units and several subunits for the Mekong delta (see Fig. 1). This paper aims to describe the former and present cropping patterns in relation to the landform, particularly the interconnected features of microlandform, water conditions, soils and the traditional methods of rice culture.
 The first part of the paper describes the methods of rice growing which were predominant in the delta before the 1960s-1970s. These methods were severely affected by the uncontrolled water conditions, which differed markedly in different landform units of the untamed delta, and may be summarized in three groups, which are characterized most distinctively by three planting methods, i. e., broadcasting, double transplanting, and single transplanting.
 The second part of the paper describes the present changes in the cropping pattern and the development of various rice growing methods. The most remarkable change is observed in the tide-affected floodplain (middle reach of the delta). Conventional double transplanting has been completely replaced by new methods like direct-seeding sa chai, and single cropping has been replaced by the year-round cultivation. Floating rice in the high floodplain (the upper reach of the delta) has also been reduced by expansion of high-yielding rice varieties. The coastal complex and the broad depression, which are affected by saltwater and sulfate acidity respectively, retain the traditional rice culture.
 The remarkable change in rice culture and land use has achieved as the result of close observation of soil, microlandform and water conditions by the farmers, and through their selective adaptation to natural environments and proper technologies.