small sprayer spray rates

[greenthumb]

How do I figure out how much per acre my sprayer is spraying. I have a 15 gallon homemade sprayer that I have made for my exmark mower. It has a 3.5 gpm flojet pump which says it has 45 psi. I have made a boom that is about 6 feet wide with five spray tips on it. I use it for liquid fertilizer and weed control in my yard which is about 2 ac. I am trying to figure out what speed I should go and etc. I have a handheld gps I can use to give me my speed as I go. The boom is mounted about 24" from the ground. In the past I just drive and apply what with what "feels to be the right amount" I think I should get a little more accurate with the cost of chemicals and gas.

thanks

 

[flINTLOCK]

You can check width of spray pattern, say 20 feet and divide into 40,000 for gross approximation of # of feet you have to travel to spray about one acre. In this case, would be 2000 feet. Use GPS track your distance. Or you could figure average ground speed by GPS in MPH, then convert to feet/minute to see how many minutes you need to spray to cover one acre. I checked the sprayer volume/minute by discharging pure water into 5 gal bucket and timing that. Your sprayer will probably put out more H20/minute than it will mixed product, since the mix is slightly more viscous than H20. I know it sounds complicated, but hopefully this has been helpful.

 

[regor66]

Just last week I bougt a spray rig and some chemicals. Fellow where I bought the stuff told me about the calibration method called "1/128th method". He had a complicated formula but I found an easier one at this site using a google search. Texas Citrus - Orchard Herbicide Application Guide
I did my calculations and it worked out great. Hope this helps.

 

[jeffinsgf]

1. Measure the width of your spray pattern.

2. Set pressure and flow as desired.

3. Either using the marks on the tank or a measuring device, determine the volume of water in your sprayer.

4. Set a constant speed.

5. Either travel a specific distance and measure the amount sprayed OR spray a specific amount and measure the distance traveled.

6. Use the data collected in Step 5 to match the desired application rate. If too much is applied, increase ground speed. If too little is applied, decrease ground speed. In either case make a few more test runs.


My sprayer covers ten feet. If I measure the amount delivered in 500 feet travelled, I can double that amount and know what is sprayed on 10,000 square feet. Multiply by 8.7 (or 9 if you are doing it in your head) to find the amount spread on an acre. If 500 feet of travel for calibration is difficult, use 250 and adjust the math accordingly.

By the way, 2 feet seems awfully high for your boom. Mine's barely a foot off the ground in use.

 

[Toolguy]

Ditto to the above advice. To do it right it is a trial and error process. Good luck.

 

[mjncad]

Get yourself one of these. Field Sprayer Calibrator, Crop, Turf & Nursery Production - GEMPLER'S

Quite easy to use as I tried it out today, and weather permitting I'll spray the real weed killer sometime between Friday and Monday.