Best watering method for mature tree (500 gal a week)

jbrukardt · Apr 4, 2017

Good afternoon everyone,

A while back you all offered some great advice for a specimen american beech I have, huge tree, about 130 foot canopy and 52" dbh. It was (and unfortunately still is) in decline with crown thinning due to root damage.

old thread: http://www.treebuzz.com/forum/threads/help-me-save-a-200-year-old-specimen-beech.34053/

The tree was a bit too sensitive to heavily airspade, so in many ways im left to let nature run its course, but one thing i can do is help the tree regrow its roots with some watering assistance.

If i've done my math right, i need to lay down about 500 gallons a week in a deep watering session. I'm on a well producing well, so the water usage isnt an issue.

I was just wonder what you all thing the best method of laying down that amount of water is. My initial plan was 4 directional sprinklers, each covering one quadrant, about 10 feet out from the base of the tree (keeping the base dry), soaking out to the root zone to simulate a rainfall. Running those for 1.5 hours or so would lay down the 500 gallons.

I have 4 inches of mulch all the way out to the drip line, so it should retain the moisture fine without runoff.

Thoughts?

Lumberjack · Apr 4, 2017

What size area are you trying to water?

Are you sure your well only produces 5.5GPM? I'm not disbelieving it, that's just fairly low compared to here. Our well produces ~12gpm @ ~ 30psi (~160' head, 1hp pump).

jbrukardt · Apr 4, 2017

the well can produce more, but i didnt want to overly stress it. so lets count that as a minimum, i figured dumping more water might saturate the top layer of the ground and cause runoff.

jbrukardt · Apr 4, 2017

the size area would be the entire root zone. So about 13273sqft.

Lumberjack · Apr 4, 2017

500 gallons over that area is only .06"... are you missing a decimal place somewhere?

jbrukardt · Apr 4, 2017

I was using a general rule of thumb i found which is to apply 10 gallons of water for every inch of trunk diameter when you water.

52 inches dbh x 10 = 520 gallons.

that incorrect? Or does the rule break when you get really big trees.

CutHighnLetFly · Apr 4, 2017

jbrukardt said:

Maybe rule of thumb kinda things should be considered a loose reference point, cause it sounds like your dealing with a very aged specimen. Trees like that need a bit more specific maintenance strategies just cause they (as well as the growing site it's in) are so unique.
If you have root issues, over watering might be creating a site condusive to things possibly detrimental to the roots, or if the thin canopy and 4" of mulch and dry weather create a really water thirsty site.
I'm not saying your wrong in your thought process, but I would try to make your plan site/tree specific

flyingsquirrel25 · Apr 4, 2017

Cuthighnletfly is right, older trees have spent their whole existence adapting to the environment it is growing in. Sometimes big change can foster a bigger or further issues. Remember trees take a long time to respond to treatments and many times the response is subtle.
That being said, I believe your 10 gal/in is too much. For new trees the rule is 5 gal per inch per week. This prevents under watering and provides enough for the new plant to acclimate. I think older trees would be less. The other rule is 1 inch of "rain" per week. This can be measured with rain gauges (or coffee cans) under the tree while using the sprinklers.

Lumberjack · Apr 4, 2017

These gallons per inch of diameter make zero sense to my mind.

Quick Googling shows there's 41-42" of rain per year in Maryland. For sake of conversation, let's assume 52 weeks in a year makes for .8" per week. .8" is ~6600 gallons over 13273sq ft, per week. I would lean towards a longer water cycle than every week, gauging off the number of rain days per year, perhaps. Assuming 6600 gallons and 5.5gpm, you'd need to run the sprinklers 20 hours per watering period.

JD3000 · Apr 4, 2017

I had been wondering what became of this big old beech.

CutHighnLetFly · Apr 5, 2017

Shouldn't thought to the timing of rain in nature be considered a little? I mean if we were to make an old tree start being active in the middle of the driest time if the year, are we creating a situation where the tree should be semi dormant, or where more than the normal evapotranspiration is happening?

My initial thought (as a young Arborist practicing preservation work, minimal field experience) would be to gauge water needs in a similar way as lumberjack is saying, but break it up to be heavier in the months coming out of and going into dormancy.
Wadda you guys think about that?

JD3000 · Apr 5, 2017

I agree. Irrigation should be based on precipitation and soil moisture conditions as well as how the soil type accepts water.

jbrukardt · Apr 5, 2017

JD3000 said:

Thanks for all your help in the old thread. Unfortunately I just ended up coming to the conclusion that there wasnt much to be done from a major preservation point of view.

jbrukardt · Apr 5, 2017

Agreed on all counts that it wouldnt be a "X gallons a week no matter what", that would be silly to not account for rain and seasons.

Unfortunately I've had no luck with professional arborists in my area after talking to a couple more after last time. I got another "dose it up with a ton of nitrogen recommendation", and one "cut it down, its nearing the end of its life".

Both these were ISI certified, but not ISI master arborists.

I'd be glad to do some legwork for one of you remotely if you needed data to make up a plan. And of course, i realize your time is valuable and can compensate at an industry rate if desired.

Lumberjack · Apr 5, 2017

I mentioned in my post gauging off the number of rain days per year. I thought it was implied, but yes, you should consider their distribution in the year.

If we're getting technical, I don't know if 41-42" of rain per year includes snow or not... I didn't google that far, I was sitting on a barstool in the hydraulic shop waiting on a hose and walking out of the bank when I made those posts. I don't know if it appreciably snows in your part of Maryland. If that rainfall number doesn't include snow, you could factor that in. If it does, you still need to factor in that a foot of snow might be an inch and a half of rain and adjust.

There are an ineffable number of variables (to me) that could go into calculating the amount of water to add to simulate rainfall. All that doesn't really matter (to me) when you consider that we are talking about a tree that is declining and average rainfall isn't likely what the tree needs in a compromised state. It's also not like we're putting a flow meter on the watering system to be able to verify application rates.

I am no longer a Certified Arborist, but 500 gallons of water over that area is imperceptible to the tree. My suggestion would be to invest in moisture gauge(s), do some research as to what a desirable moisture range is, and water to keep the area on the average in that range. Minor overwatering is more chronic than acute to my thinking, as opposed to under watering adding stress to an already stressed tree which may culminate in an acute presentation, as far as "tree time" goes.

Nitrogen isn't a stressed tree's friend. It stimulates growth which the tree may not be able to sustain and diverts resources away from compartmentalizing and energy storage.

jbrukardt · Apr 5, 2017

Lumberjack said:

I mentioned in my post gauging off the number of rain days per year. I thought it was implied, but yes, you should consider their distribution in the year.

If we're getting technical, I don't know if 41-42" of rain per year includes snow or not... I didn't google that far, I was sitting on a barstool in the hydraulic shop waiting on a hose and walking out of the bank when I made those posts. I don't know if it appreciably snows in your part of Maryland. If that rainfall number doesn't include snow, you could factor that in. If it does, you still need to factor in that a foot of snow might be an inch and a half of rain and adjust.

There are an ineffable number of variables (to me) that could go into calculating the amount of water to add to simulate rainfall. All that doesn't really matter (to me) when you consider that we are talking about a tree that is declining and average rainfall isn't likely what the tree needs in a compromised state. It's also not like we're putting a flow meter on the watering system to be able to verify application rates.

I am no longer a Certified Arborist, but 500 gallons of water over that area is imperceptible to the tree. My suggestion would be to invest in moisture gauge(s), do some research as to what a desirable moisture range is, and water to keep the area on the average in that range. Minor overwatering is more chronic than acute to my thinking, as opposed to under watering adding stress to an already stressed tree which may culminate in an acute presentation, as far as "tree time" goes.

Nitrogen isn't a stressed tree's friend. It stimulates growth which the tree may not be able to sustain and diverts resources away from compartmentalizing and energy storage.

I would like to some good moisture gauges. Any recommendations as to brand/model?