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Static and Kinematic Tests for Determining Spreaders Effective Width
L. Maldaner, J. Molin, T. Canata, B. Passalaqua, J. J. Quirós
ESALQ

Spinner box spreaders are intensively used in Brazil for variable rate applications of lime in agriculture. The control of that operation is a challenging issue because of the complexity involved on the interactions between product and machine. Quantification of transverse distribution of solids thrown from the spinner box spreaders involves dynamic conditions tests where the material deposited on trays is evaluated along the pass of the machinery. There is a need of alternative testing methods capable to make the spreader evaluations more efficient. The objective of this study was to compare three methods for the determination of effective width for limestone application. A double disc spinner box spreader pulled by the PTO tractor was used. The flow rate was set at 3.0 kg s-1 and three replicates of kinematic, static grid, and radial static scenarios were evaluated. The speed in kinematic test was set at 1.21 m s-1. During the static evaluations the spreader stayed in operation for 30 s with a PTO speed of 540 rpm. The radial test was done with nine rows of trays separated by an angle of 20º, starting joined in one side, and then finishing separated by 0.25 m on the other side. For all scenarios plastic trays of dimensions 1.00 x 0.25 x 0.15 m were used to collect the material of the samples. To get the weight of the samples a balance with 0.01 g sensibility and a capacity of 5,000 g was used. Static grid and kinematic tests were analyzed based on the coefficient of variation at 20% using the software Adulanço, while the data of the radial test was interpolated using QGIS in a grid of 0.5 m x 0.5 m. Regarding the results between kinematic and static grid tests, the highest mean relative error of effective width was 21.6%. Using Tukey test at 5% level some statistical differences were observed depending on the trajectory. Data had high CV variation (ranged between 78.51% and 115.51%) among replicate treatments, so that further studies are needed to understand those variability aspects.

Keyword: distribution test, limestone, spinner box width