A Compact Variable-Rate Sprayer for Teaching Precision Agriculture

Abstract

A compact variable rate application (VRA) sprayer for use in teaching precision agriculture (PA) concepts and skills was developed and field tested. A 3.66-m boom-type field sprayer with a 227-L tank was used as the base unit. The sprayer was designed to be towed with an all-terrain vehicle (ATV) and was equipped with a 12 VDC electric diaphragm pump. Off-the-shelf Global Positioning System (GPS) and variable rate application (VRA) components were modified as necessary and installed on the base unit. For field testing, a 13.3-m wide by 97.5-m long test course was laid out and spraying prescriptions were written for field speeds of 2.74-km h and 5.47-km h. Forty replications at each speed were conducted over two days to evaluate position accuracy (actual on/off point versus prescribed on/off point). With a 2s delay programmed into the unit, the mean position accuracy was 0.30-m and 1.02-m at 2.74-kn h and 5.47-km h, respectively. Application accuracy tests revealed the capacity of the electric diaphragm pump was not sufficient to allow effective regulation of application rates due to flow sensor requirements. This limitation has little practical effect on the sprayer’s use as a teaching model, since the primary educational benefits center around the larger issues of understanding precision agriculture, collecting and managing spatial agronomic data, developing field and prescription maps, operating the equipment, and integrating multiple technology systems.