Theses and Dissertations

Issuing Body

Mississippi State University


Chesser, Gary D.

Committee Member

Lowe, John W.

Committee Member

Reynolds, Daniel B.

Date of Degree


Document Type

Graduate Thesis - Open Access


Engineering Technology

Degree Name

Doctor of Philosophy (Ph.D)


College of Agriculture and Life Sciences


College of Agriculture and Life Sciences


Variable-rate technologies coupled with broadcast spray systems serve to reduce chemical inputs, misapplication of chemicals, and environmental pollution, thus improving profitability and sustainability. Sprayer variable rate control involves using pulse width modulation (PWM) solenoids and/or direct chemical injection to adjust the application rate. The objectives of this research were to: outfit a conventional broadcast sprayer with PWM and direct inject technologies; evaluate the accuracy of the PWM system to control application rate for strait line and turn segments; and characterize the direct injection system’s transport delay time. For the PWM evaluation, the mean flow rate and coefficient of variation of individual nozzles indicated consistent performance. For the direct injection evaluation, the manufacturer recommended plumbing scheme and injection point location resulted in unsatisfactory delay times, ranging from 105 to 150s for the 8 km h-1 (5 mph) speed and 60 to 90s for the 16 km h-1 (10 mph) speed.

Included in

Agriculture Commons