soil injection - required psi?

[ATH]

For those doing soil injection (fertilizer, Merit, etc...):

How much pressure is needed to do effective soil injection?

I suppose the answer will depend on hole spacing (higher psi=wider spacing between holes??) But what is reasonable? I am looking at different spray rig options, and am doubting it is really going to make sense to pay for a 450+ psi unit. I'm going to avoid high canopy sprays--somebody else can have those.

Second question while I'm at it...is a 50-75 gallon tank enough, or will that leave me spending half my day finding more water?

Finally, I know Davey is using portable hand pumps (saw them injecting for ALB in Central Park a couple of weeks ago). Anybody here doing that too? If so, what is your set-up. I have been looking, and it seems the higher pressure portable tanks are backpack sprayers. Haven't seen any 4-5 gallon small tank sprayers that I could put on a dolly or the like.

Thanks!

 

[Castenea]

I use 150-200PSI from a pump capable of a great deal more pressure ~800PSI

Since I use a truck setup my mix tank for injecting is either 35 or 65 gal, but I have a 525 gallon tank to ensure that finding more water is not a problem. Big soil injection can have me spending a lot of time mixing material on the job though.

The bigger pumps can generate higher pressures and move a lot more material, but I like them for their flatter power curves (less pulsation in the spray hose). I also spray smaller trees, but seldom attempt big trees since attempting to hit high canopy is problematic and the higher you go the bigger the issues you have with drift

 

[John Paul Sanborn]

IMO 150 should be the max pressure, otherwise you may damage roots with your squirt.

Another thing to realize is that that pressure is not at the gun, but before the reel. The longer the hose, the more loss you will get at the gun.