Performance Assessment of VRT-based Granular Fertilizers Broadcasting Systems

Moustafa A Fadel


Due to environmental concerns in addition to economical considerations, Variable
Rate Treatment concept is widely applied in the agricultural arena. Granular
fertilizers’ broadcasting is one of the most growing applications employing VRT and
GPS guidance technologies. Although such systems are commercially produced,
standards for performance assessment yet to be developed. ASAE S431.2 provides a
standard procedure for testing broadcasters performance. However , this standard does
not cover the testing of broadcast spreaders with VRT. Three different testing
methodologies are presented in this paper to lay the basics of any testing procedures
to be developed. The suggested procedure is widely applicable assessment process
and not specifically designed to evaluate a specific system. A semi-automatic rotary
variable rate broadcaster equipped with GPS real time guidance was designed and
built locally. Evaluation procedures focused on differences between the prescribed
and the actually applied amounts; between nutrient (P2O5) levels before and after
treatment and between targeted and actual nutrient levels after treatment in GPS
identified points in the field.

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