Rate response assessment from various granular VRT applicators

J. P. Fulton, S. A. Shearer, S. F. Higgins, M. J. Darr, T. S. Stombaugh

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


Variable-rate technology (VRT) adds complexity to application equipment, thereby confounding the assessment of applicator performance. The intent of this investigation was to assess the rate response of various VRT granular applicators: two spinner spreaders (A and B), and two pneumatic applicators (C and D). Variable-rate (VR) tests were conducted to quantify the rate response characteristics (delay and transition times) for the applicators. A sigmoidal function was used to model the rate response for five of the six tests. Applicator A exhibited a linear response during decreasing rate changes. Results indicated that only applicator B demonstrated consistent delay and transition times, enabling the use of a single "look-ahead" time for rate response time correction. Contouring of prescription maps increased the transition times for applicator D by enlarging the adjustment area between management zones. Rate changes were quicker for the two newer VR control systems, signifying advancement in hydraulic control valve technology. This research illustrates the need for standard testing protocols for VRT systems to help guide VRT software developers, equipment manufacturers, and end users.

Original languageEnglish
Pages (from-to)2095-2103
Number of pages9
JournalTransactions of the ASABE
Issue number6
StatePublished - Nov 2005


  • Fertilizer distributors
  • Pneumatic
  • Potassium
  • Precision agriculture
  • Site-specific management
  • Spinner spreaders
  • Variable-rate application and technology

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)


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