Individual nozzles should be checked for accuracy of delivery. This nnay 

 be done by measuring the volume of spray delivered by each nozzle in 1 

 minute. There are many methods of calibrating a sprayer. One method is 

 given belo'w for calibrating each of three different types. 



HOW TO DETERMINE PER-ACRE OUTPUT OF SPRAYERS 



1. Power sprayers 



(a) Fill the spray tank -with water. Make sure it is connpletely full. 



(b) Drive in a straight line for exactly 220 yards, operating the sprayer at 

 exactly the sann.e pressure and tractor speed planned for use in the 

 field. It is a good practice to mark that notch on the throttle. (A tractor 

 travels slow^er in a soft field than on hard ground.) 



(c) Upon reaching the 220-yard mark, stop spraying. Then measure care- 

 fully the amount of water needed to refill the tank (a quart jar is 

 satisfactory). 



(d) Convert the nunnber of quarts of water used into gallons by dividing by 

 4, and then multiply this figure by 66. Divide the result by the width in 

 feet of the strip sprayed. The answer obtained is the number of gallons 

 the sprayer will put on 1 acre when it is operated at the same settings. 

 Example: Suppose the sprayer boom sprays a strip 20 feet wide. After 

 traveling 220 yards it takes 6 quarts to refill the tank. Six quarts 

 divided by 4 equals l-l/2 gallons. Multiply 66 by 1-1/2, which equals 

 99. Then divide 99 by 20 feet (the width in feet of the sprayed strip). The 

 answer is just under 5, which is the rate of application in gallons per 

 acre. 



Comments and Precautions . --In some roAv crops only anarrow^ band is 

 sprayed, centered over the row, such as in pre-emergence treatments in 

 cotton and soybeans. When treatnnents are made in this manner the rate 

 of treatment is in ternns of the area treated and not in terms of per-acre 

 of actual crop. For example, in cotton with 36-inch row spacing, if a 12- 

 inch band is treated at l-l/2 pounds per acre (based on the area actually 

 treated ) the amount of chemical per acre of cotton would be 1/ 2 pound. 



2, Hand-Type Boom Sprayers 



Example: 3 -gallon knapsack sprayer with a boom that sprays a 4-foot 

 swath. Fill sprayer and walk at a steady pace, maintaining a constant tank 

 pressure, for 110 yards. Refill tank, change number of quarts required to 

 refill sprayer into gallons, and multiply by 132. Divide this figure by the 

 width of the spray swath (4 feet). The answer is the number of gallons the 

 hand sprayer is delivering per acre at the pace "walked and the tank pressure 

 maintained. 



If too much spray is being applied, walk faster or use less tank pressure. 

 For marked changes in rate of application, it may be necessary to obtain 

 different nozzle tips. 



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