Study on the Development of the Bulblet Harvester of Chinese Yam in Sand Dune Field (Part 1)
Physical Properties of Bulblet and Sieve Analysis of Dune Sand
1992 Volume 27 Issue 2 Pages 125-131
Details
1992 Volume 27 Issue 2 Pages 125-131
The Chinese Yam which is one of specialized product in sand dune field forms the axillary buds called bulblets or propagules grown along the aerial leaf axil, and falls a large number of them on the field surface at the harvesting season. The fallen bulblets are partly harvested by manual mode, but mostly are left in the field as it is because of labor shortage. The object of this paper is to obtain the practical designing information being suitable for the development of the bulblet harvester. Several findings concerning the physical properties of bulblets and sieve analysis of dune sand can be drawn as follows.
1) The amount of bulblets fallen in the field is approximately 780kg and more than 1.3 million pieces per 10a. This scattering distribution seems to be affected considerably by the yearly sites conditions.
2) An average diameter of single bulblet shows 10.3mm and the average mass takes 0.1 to 3.3g, while the average diameter ranges 5 to 20mm.
3) Morphologically, more than 40% of all the samples are dominated by the ones of round shape, and they tend to be more round slightly with the decrease of the bulblet size.
4) The static coefficient of friction of the bulb lets fall within less than 0.6 on the inclined board covered by vinyl chloride.
5) When serving dune sand at less than 1.5% d.b. soil moisture content on the sieve, the dune sand tends to flow downwards immediately after supply without any retention on to the sieve even under no oscillating condition. Furthermore, with the increase of moisture content at exceeding 2% d.b., the amount of dune sand passed through sieve begings to decrease suddenly and little flow could take place at more than 3%.
6) To attain 100% in terms or the percentage of dune sand passed through sieve, the working depth of the harvester should be maintained as shallow as possible in dry dune sand, which is moisture content about 0.3%, generally formed under the fine climate condition.
