SWR Tested, Approved and Recommended by Iowa State University




College of Agriculture
Seed Science Center
FAX 515 294-2014




A Sidewall Return Drag Conveyor Model SWR 12 manufactured by Sidney Manufacturing Company was tested at the Committee for Agricultural Development at Iowa State University. Three soybean varieties were transported through the system twice to a distance of 40 feet total at two speeds and three capacities. Composite samples were collected before conveying, after the first pass and after the second pass. Samples collected were tested for split, warm germination and TZ tests to determine the amount of damage impacted to the seed during the conveying process.


The objective of the research was to determine the amount of damage that will occur to the soybean seed being passed through the conveying system.


The procedure includes using a Sidewall Return Drag flight conveyor handling system, Model SWR 12. The drag conveyor transported the seed to an effective length of 40 at two horizontal speeds of 100 and 75 feet per minute. The conveyor had one intermediate discharge gate and one bolted section of which the material passed over twice. Three soybean varieties with different degrees of susceptibility to mechanical damage were used. One five-pound composite sample was taken before the seed enters the drag conveyor and another at the discharge end of the conveyor. A third five-pound composite was also taken after the seed was sent through the system a second time. Each sample was taken by moving the sampling container across the stream of seed to obtain a representative sample. All samples were then taken to the laboratory at the Seed Science Center where they were tested for percent of split, seed coat damage using the Hypochlorite Soak Test which is also known as the Clorox test, germination and tetrazolium test for estimating viability of seed.

The conveyor was operated at 90%, 11% and 2% of its full capacity. Capacity was determined by collecting the total amount of seed from the discharge end of the drag conveyor for a known period of time and weighing the collected sample and calculating the percent of the collected samples with reference to the specification capacity given by the manufacturing company. The conveyor was operated at the 11% capacity i.e. below the chain line to simulate what the majority of seed companies do to avoid having seed carried on the chain. The 2% of full capacity was meant to simulate what happens if the conveyor was operating slightly empty.


Three varieties of soybean were utilized, 38003, 2630 and H7261575. Variety 2630 seems to be less susceptible to mechanical damage, followed by H7261575 and 38003. The splits result is accumulative and seems to numerically increase as the number of passes increase but not to the extent the would put it in a significant level, (*see tables 1, 2, and 3). The split percentage was within the acceptable level as compared to the grading system of country elevators. Country elevators grade soybean as grade 1, 2, 3 and 4 if the corresponding percent split is at about 10, 20, 30, and 40 percent respectively. The number of passes showed no significant effect on soak test, warm germination and the viability test (TZ), (*see table 4).

For all varieties tested, the speeds at which the conveyor was operated showed no significant on splits, warm germination and TZ test. This indicates that it makes no difference running the conveyor at 100 fpm (*see Table 5). The capacities at which the conveyor was operated showed no significant impact on splits, soak, warm germination and TZ test indicating that running the conveyor at full capacity, below the chain or dribbling would not effect the quality of the seed conveyed (*see Table 6).


The results indicated that this Sidewall Return Drag Conveyor at the capacities and speeds it was operated did not cause substantial damage to the three varieties of soybeans tested. This will allow us to conclude that this conveyor is a good conveyor and we recommend it for any one who is interested in a conveyor that is gentle in handling seed.

Kamal M. Adam, Ph.D.
Conditioning Research & Training Program Coordinator

* Charts available upon request

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