Influences of puddling practices on shrinkage characteristics of clayey paddy soils
2002
Yoshida, S. (National Agricultural Research Center, Tsukuba, Ibaraki (Japan)) | Adachi, K.
The effect of puddling on cracking patterns is substantial in clayey paddy fields. The present study examined the relationship between puddling intensity and the resulting shrinkage characteristics. The experiment was performed in a clayey paddy field. Puddling intensity was examined as a unique factor. Three intensity levels: light (puddling once), medium (puddling three times), and heavy (puddling five times) at each level with three repetitions, were assigned across nine plots (three plots per level). Disturbed soil and undisturbed soil were sampled in each plot just after puddling, and again three months after puddling. Just after puddling, the puddling intensity significantly affected the content of the remaining clods, water retentivity, and the increment of air-filled pores induced by fracturing forces during desiccation, but these differences are estimated to have had little effect on the expected volume of cracks. Three months after puddling, the difference in these properties due to the puddling intensity became unclear, with the exception of the content of clods. Thus, the important properties which control the variation in cracking geometry due to puddling intensity cannot be sensed by the shrinkage test for core samples. The direct measurement of soil structure, such as the content of remaining clods, reflects the differences in the mechanical properties due to puddling intensity.
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