Test beds are prepared for cassava planting by using the method of agriculturalist. Plant
‘Kasetsart 50’ variety in a bed prepared with the average distance between the rows being
1.0 meter and the distance between the plants being 0.85 meters. The test bed is separated
into 5 small plots each with the size of 3x80 meters. This bed is used for testing once a
month during the harvest season (October –February). There are five tests altogether. In
each test soil moisture will be reduced according to the nature of the area. The study is
divided into two steps:
2.1 Function Test of Cassava Digging and Preparing Unit
The Digging and Preparing Unit is used to dig up cassava rhizomes from the ground, break
the soil clods into smaller sizes after digging and then to put the cassava rhizomes on the
broken soil clods to wait for the Conveying Unit attached to the back of the Digging Unit to
scoop and convey the cassava rhizomes to the collecting trailer.
The Digging Unit used in study (Fig. 2) is designed to break the soil clods while digging the
cassava rhizomes from the ground. The sifter at the end of Digging Unit will separate the
cassava rhizomes from the soil after digging and make it possible to put them on the ground
after the excavation.
Fig. 2. Feature of the test kit for cassava digging and preparing unit
Factors used in testing consist of soil moisture at 5 levels (soil moisture in October,
November, December, January and February). The declined angle test of the digger is at 3
levels: 20, 25 and 30 degrees.
Factors that control the stability during the testing period consist of a digger width of 700mm,
a digger length of 200 mm and a speed of 0.69m/s. (2.5 km./hr.) without being connected to
the conveying unit.
Result testing mean consists of percentage of soil clods bigger than 75 mm, the average
size of soil clod, and the draft force measured by the method of RNAM Test Code and
Procedure for Farm Machinery (RNAM, 1995). The details of the testing are as follows:
2.1.1 Test in soil that has moisture at Level 1 and randomly test in October. Prepare the bed
by cutting down cassava plant 200-300 mm. above the ground.
2.1.2 Adjust digger to declined angle of 20 degrees.