Masters Theses


R. K. Patel

Date of Award


Degree Type


Degree Name

Master of Science


Biosystems Engineering

Major Professor

E. K. Boyce

Committee Members

D. O. Boxter, H. Andrews


A weed is an undesirable plant which competes with crops for water, light, and mineral nutrients. The use of chemical herbicides is a successful method of weed control,however, the herbicide must be applied accurately and efficiently. A wettable powder herbicide has low solubility in liquid medium. The insoluble nature of this material presents two problems of abrasion and agitation. The abrasive effect of the wettable powder can cause wear in the spraying system components. The objectives of this study were to determine the abrasive effect of wettable powder herbicides:atrazine and nitralin, in varying concentrations in different sizes of brass, hardened stainless steel, and nylon nozzle orifice tips, and with relation of hours of use.The discharge capacity of each nozzle tips were measured on a nozzle calibration apparatus before each weartest. The nozzle tips were rechecked at intervals of 3.5hours of use to determine the percentage change in the discharge capacity. In this study, 33 brass and 12 hardened stainless steel nozzle tips of four different sizes: 8001,8002, 8003, and 8004, and nine nylon nozzles of two different sizes: 12NF and 20NF, were tested using several concentrations of atrazine and nitralin as the wettable powder herbicide.The increase in the discharge capacity of the brassand hardened stainless steel nozzle tips was caused by the wear characteristics of the wettable powder. The amount of increase in nozzle discharge capacity ranged from 0.00 percent for stainless steel to 27.65 per cent for brass nozzles.The increase in the discharge capacity of brass and hardened stainless steel nozzle tips was more during the first few hours of use, and was directly related to the concentration of the spray material. The brass nozzle tips had received greater and more rapid wear compared to the hardened stainless steel nozzle tips. The abrasive effect of the spray mixture was more severe on the smaller size nozzle tips as compared to the larger ones. With equal concentration,nitralin was more abrasive than was atrazine. Nylon nozzles \showed a range of 1.47 to 5.71 per cent decrease in the discharge capacity.

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