Mainline on a side hill

[Biz]

I am setting up a 300' mainline on a side hill with minimal slope (3%). It is 3/4" mainline and will have 40-50 taps connected to a diaphragm pump. I have most of my taps on the uphill side with laterals pitched towards the mainline. On the downhill side of the mainline there are some tappable trees, but they are 2-4 feet below the mainline. I cannot run a second mainline or move it since there would be near zero slope. I am wondering if I can run a lateral uphill to the mainline and get any kind of production from it. I am OK losing a couple inches of vacuum on those few taps. If a 5/16" "uphill" lateral won't work, what about a 3/16" lateral? It seems like it should work with 3/16 laterals since sap can flow uphill but not so much with 5/16. I may try this in a couple places and put gauges out to see how it works. Just wondering if anybody has tried anything like this.

Dave

[Brian]

I have some 5/16 tubing lines below the mainline for that same reason and I get what I get. The only problem is when I get hard freezes it pops the line or a spout. I try to have the spouts higher than the mainline when ever possable.There is always a sap ladder too.

[VTnewguy]

I believe they call that tapping below the lateral line. Will work if you can keep liquid in the diaphragm pump.

[SeanD]

I have a similar situation where I have to keep the mainline up the hill to maintain slope and miss out on some very nice trees below. Last year when I put that setup on vac, I decided to tap the trees below the mainline. I went as high as I could on the trees and lowered the mainline a bit to help. I don't have any gauges on those lats, but I figured something is better than nothing. That was my first year on vac at that location, so I don't have an apples-apples comparison, but the whole spot did very well.

[DrTimPerkins]

There are three lines of thinking on this:

1. Some just won't bother tapping them since they are below the mainline.
2. Tap them as high on the stem as reasonably possible and have a slight uphill grade to the mainline.
3. Tap them as normal, have the line run down towards the mainline, but put a post and short vertical up into the mainline.

Hydraulically it shouldn't to make a lot of difference. Functionally #2 is simpler. This is what we do for a fairly small number of trees that are close to the mainline, but just a few feet (max) below the line (in elevation).

3/16" tubing wouldn't provide any benefit and would probably clog more quickly in that setting.

Tapping below the lateral (which Brian mentioned) is similar, but is a technique used when there has been extensive tapping (or overtapping) within the normal tapping band (above the lateral). It is done to access more functional sapwood in order to avoid hitting stained wood (which has serious impacts on yield and revenue). More info at:
https://mapleresearch.org/pub/m1216belowlateral/
https://www.youtube.com/watch?v=v-EEYgL7Lt0&list=PLZP4fDl-nB9-4aZkQyDR070QpxcAr02q5&index=6&t=5s
https://www.youtube.com/watch?v=04m3SQvcGY4&list=PLZP4fDl-nB9-4aZkQyDR070QpxcAr02q5&index=8&t=101s

[tcross]

has there been any research showing the differences between tapping higher up on the tree stem above the main line (say using a ladder you get the tap 8' up the stem) vs having your lateral at a slight incline to the mainline. i'm assuming there hasn't been. however i go through this decision each year... climb up a ladder and tap or have a slight incline to the main line. i only have 15-20 trees like this, so i usually just climb the ladder. however if it didn't matter, i'd rather not have to lug the ladder into the woods. i suppose the other option is a sap ladder...

[ennismaple]

has there been any research showing the differences between tapping higher up on the tree stem above the main line (say using a ladder you get the tap 8' up the stem) vs having your lateral at a slight incline to the mainline. i'm assuming there hasn't been. however i go through this decision each year... climb up a ladder and tap or have a slight incline to the main line. i only have 15-20 trees like this, so i usually just climb the ladder. however if it didn't matter, i'd rather not have to lug the ladder into the woods. i suppose the other option is a sap ladder... That depends on your vacuum levels - you can get away with pulling sap more uphill at 25"Hg than at 15"Hg. We tap a couple trees beside a trail where the mainline is 10 feet off the ground. We put the lateral at normal height and barber-pole'd the lateral around the tree up to the mainline. We'll also run laterals below the lowest mainline along a hill that rise 3 or 4 feet to the mainline. Not ideal, but better than not tapping them.

[tcross]

i'm running 27-28" of vacuum. i was kind of curious which route is the better route to take? tapping higher up on the tree stem probably wouldn't produce as much sap as taping normal height, but it also won't be froze up during the early parts of the sap run. vs... taping lower and running the line up hill to the main where there's probably less vacuum to the tap hole when sap is flowing, but getting more sap due to tap location on the stem? (if all that makes sense?) Probably pretty safe to assume i'm splitting hairs, however i'm curious if anyone knew, or had an opinion on which is the better route?

[DrTimPerkins]

That depends on your vacuum levels - you can get away with pulling sap more uphill at 25"Hg than at 15"Hg.

Absolutely. Good vacuum makes this a much more viable option.


We tap a couple trees beside a trail where the mainline is 10 feet off the ground. We put the lateral at normal height and barber-pole'd the lateral around the tree up to the mainline. We'll also run laterals below the lowest mainline along a hill that rise 3 or 4 feet to the mainline. Not ideal, but better than not tapping them.

Yes, this is a variation of my #2 below. The drawback I've heard is that it takes longer for the "dropline" that is coiled around the tree several times to thaw, particularly on the north sides. Not sure how much of a factor that is.


i'm running 27-28" of vacuum. i was kind of curious which route is the better route to take? tapping higher up on the tree stem probably wouldn't produce as much sap as taping normal height, but it also won't be froze up during the early parts of the sap run. vs... taping lower and running the line up hill to the main where there's probably less vacuum to the tap hole when sap is flowing, but getting more sap due to tap location on the stem? (if all that makes sense?) Probably pretty safe to assume i'm splitting hairs, however i'm curious if anyone knew, or had an opinion on which is the better route?

Yes, it'll probably a matter of splitting hairs and there isn't a substantial difference in approach. There hasn't been a lot of research on it that I'm aware of. Tapping height has a very slight effect...the yield may be a tad lower but the sugar content is typically a tad higher, so overall it's probably a wash. Tapping below the lateral 24" doesn't produce significantly less sap than tapping 24" above the lateral. A foot of water is about 0.9" Hg, so a rise of 6 ft might mean a loss of about 5" Hg, so maybe about 25% reduction in sap yield.

Note that the research on tapping below the lateral showed that using CV spouts to reduce backflow from that approach was highly recommended. Maybe not needed if the drops/spouts are new, but otherwise they should be used in this setting (tapping below the lateral or tapping below the mainline).