Hugelkultur Temperature Experiment

I noticed the other day that my small hugelkultur bed seemed to be generally warmer than the surrounding soil.
So, I decided to conduct a small experiment. I have been logging my results here --> Hugelkultur Temperature Experiment.

I have been taking temperature measurements from my huguelkultur bed, my raised bed, the ground, and the ambient air. I have been
taking readings in the early morning (before the sun breaks the treetops), mid-day (as close to noon as possible), and evening (usually 1 - 2 hours after sunset).

The results have been somewhat surprising. The hugelkultur bed temp has remained mostly stable.



At one point (5/22M), it had been raining all night long, the air temp was 61.4, and the hugulkultur bed was still at 82.5.

All temperatures are in Fahrenheit, of course.

Just though I would share what I have so far. This is an ongoing experiment, and I am very interested in seeing how well it holds heat through
the colder nights and shorter days of winter.

That is very interesting. Good information. Thank you for sharing.

I see where the raised bed - ground readings are consistently nearly equal. Your hugel bed appears (to me) that it has significant decomposing activity going on, which would account for the higher and more even temps.

It would be interesting to see the results in the winter months, as well as after the decomposing process has progressed past peak.

Thanks for posting this Ryan.

This brings up a question I have been pondering. I am new and the answer may be obvious and I just have not run across it yet.

I am planning to replace my raised bed with a 40' long 3-4' high hugelbed this fall for next years garden. IF I understand the huglebed concept correctly, I build the bed and sow my seed in the fall rather than start seedlings inside and transplant. then you let some of that years crop go to seed so it replenishes for the following years garden. If these beds are staying warmer than regular ground temp it seem that the seeds would germinate earlier in the year causing a frost risk.

If using a hugelcultre type of bed, do you need to keep a hoop cover over it until the danger of frost is over or does the warmth rising from the bed protect the young plants form frost? if this bed is at 82F in late March / early April, I would think that warmth may very well protect against night time frost unless it was excessively heavy...but I just don't know.

Ray

@ John -
I was thinking that the temperature difference was probably due to the increased solar exposure the bed gets. I hadn't considered
that it might be due to decomposition.
For the next few days I am going to place a canopy over the bed to limit or eliminate direct sunlight. I will plot these temperature
results on a separate chart. I suppose the results should give me a better idea of the cause.
Thanks for the idea!

@ Ray Clover -
I'm new to this as well, I am not really sure what the results would be. This year's spring was warmer than normal, we planted
over a month before our last frost date and didn't have any trouble. But this is only our 3rd year of gardening, so I don't have a
lot of experience to draw on.

John, so far it looks like you are right. I have kept all direct sunlight off of the bed and it doesn't seem
to be affecting the temperature by any significant amount so far.

Thank you for this information Ryan. How deep did you insert the probes and were you relitively consistent with this?

I would think that John is right regarding decomposition heat. A hugel bed is also a giant thermal blanket of mulch, so the evenness of temperature may have to do with the moderating affect while any rise above the ambient soil temperature would seem to be from either the sun or biological processes or both.

The probe is 5 inches long and I just buried it completely each time. I chose a memorable spot for each area, so each reading
was taken within about a 2 inch circle from the original.

Sounds like you can skate by the first few frosts without any problems.

This is great to see. I noticed that my hugelkulturs are warmer to plant in than the surrounding soil (unless it's 90 F or hotter out in which case they feel cooler) but never measured the temps. I'll have to try this out.

I would like to see how other hugel beds compare to mine. If you do try it, please post the results here.

I'm interested in tracking temps. i'll see what I can do. any info I get organized i'll post

another item of interest would be variation in temp on a single bed from different aspects or heights.

I guess a final note would be to consider general architecture of the beds: shape, slope, size, soil type, orientation....but one thing at a time.

I took a gamble by planting a little early this year, and I lost! We had a frost two nights ago; however, everything on my hugel bed survived the night. There were no other survivors. I'm not sure if there are other factors that may have caused this, but I thought ya'll might be interested.

It's a shame you lost everything else, but I find it very interesting that the hugelkultur bed survived. Thank you for sharing!