Several researchers have recently argued that the tai-tien system described in The Food and Money Chapter (Shih-huo-chih) of the Han Shu is perhaps a method of irrigation farming. In this article the author wants to show how we should think about the close relationship between the area where the tai-tien system was carried out and the area where large-scale river channels were constructed and repaired during the Ch'in and Han dynasties. The success or failure of irrigation farming in this area was due to, first, the draining qualities of the loess soil and, secondly, the extent of preservation of the quality of water used to grow paddy rice. At Cheng-Ruo-ch'u (鄭国渠) these standards were maintained. But, at Lung-shou-ch'u (龍首渠) they were not maintained, as there were deficiencies in the quality of the water and soil. Thus, in the Wei River (渭河) basin during the Han large-scale irriga-tion projects usually not only failed due to soil conditions. Also, ignorance of soil enrichment methods, in the long run, Conabout eventual deterioration of the soil's productive power. brought sequently, the tai-tien method can be explainted as an attempt to use deep-plowing to revive and improve the soil quality of land that irrigation had gradually turned to bracken. Also, the size of the ditches in the tai-tien system might, according to commonly held theories, be one Han foot deep, one Han foot wide, and the full length of one mou, which itself would be equal to six Han feet wide and 1440 Han feet long. For furrowing the fields they might use a plow with a mould-board (a tool which has recently been unearthed) ; this plow was drawn by two oxen and handled by one man. They also used a drill drawn by one man and handled by another man. Thus, it was possible to make deep trenches. Furrow planting seems to have been a traditional form of husbandry that suited the soil of the Wei River Basin. The introduction of the drill and the new plow from other parts of China led to the success of the tai-tien method, which in turn, led to the expansion of arable land and the improvement of the salinized soil in this area.
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