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Pomace as understory mulch

Posted by Steve Dagger 
Pomace as understory mulch
April 13, 2020 08:30PM
A simple technique I've begun experimenting with the past few years is to randomly compost the pulp left from pressing cider in the peripheral zone of bearing trees with the intuition that the returned organic matter will be conducive to improving both the profile of desirable nutrients and micro-organisms. I initially wondered about adverse effects on soil pH or creating conditions favorable to pathogenic fungi, bacteria or insect pests but, so far, I have not noticed any obvious problems though I haven't done any comparative soil tests or data collection. I mix the pulp lightly with existing litter and prunings and don't lay it on too thick in any one spot and it seems to break down relatively quickly.

As a holistically oriented grower a primary objective of mine is to let nature do as much of the work as possible. The "theory" behind this simple technique is that the microbial diversity present on my organic apples, much of which would survive in the pomace, will go on to create spores that would contribute to effective arboreal microbe populations in addition to the decomposing pulp returning nutrients essential for plant health to the soils in the orchard understory. Weather variation from year to year will certainly influence which microbial populations and decomposers flourish and which don't but starting with diverse populations that have already proven adapted should push the dynamics in a favorable direction. That's my theory anyway.

Pommes de Terre Acres
USDA Zone 5 - Dixon, Montana
Intermountain West Region

Edited 2 time(s). Last edit at 04/20/2020 06:43PM by Steve Dagger.
Re: Pomace as understory mulch
October 28, 2020 04:14PM
I think this is a wise approach. Please see my post from today in Leaf Mulch. I would suggest taking some soil tests for both chemical/mineral and soil food web test to follow the changes. You can also buy a cheap microscope and see the shift in soil biota (with some training) or just stick a shovel in the soil and observe the macrobiota changes as well. I am doing this currently with a compost project where I am following the changes in soil characteristics between different treatments. In any case, I support your approach and encourage you to document and measure the changes.

Mike Biltonen, Know Your Roots
Zone 5b in New York
Re: Pomace as understory mulch
January 15, 2021 08:20PM
To take this a step further, we are thinking about inoculating wood chip mulch strips that we have in the orchard with culinary mushrooms. We're pondering if a woodchip/pomace mulch would support mushrooms. Seeing as we all have so much pomace, wondering if anyone was tried pomace in mushroom cultivation yet?

Re: Pomace as understory mulch
January 15, 2021 08:42PM

Great to see your post, as one of my favorite future schemes is using pomace to grow mushrooms! Or more probably, selling the pomace very cheaply to local mushroom growers as a substrate. My interest in this was peaked years ago as I researched avenues for pomace disposal/utilization, and discovered that pomace is a useable mushroom substrate, albeit most often mixed with other materials. I have offered pomace to three different mushroom farms in the area, and all expressed surprise that it can be used as such . . . and none have followed up beyond that, so I've concluded that it will take demonstrable evidence of success to get anyone seriously interested.

I also aspire (way, way in the perfectly managed orchard of the future) to grow mushrooms commercially in between trees, so I especially like where you're going with the pomace mulch in the orchard, and eagerly anticipate the results of your experiment. We are still finding it very necessary to utilize hefty doses of lime sulfur, copper, etc. in our dormant sprays, so this has tempered my enthusiasm for purchasing spawn and inoculating the orchard rows with culinary mushrooms at this time.

Kordick Family Farm
Westfield, NC
Zone 7a
Re: Pomace as understory mulch
January 15, 2021 09:55PM
That is so cool is hear! I can't wait for pressing season now!
We also have to spray more sulfur than we like but were thinking about it in sections where we are not spraying sulfur yet (where the trees are still young). We also have several acres of coniferous woodlot with many "hiding" spots for growing mushrooms in designated straw or wood chip beds/gardens which work well with oysters and wine caps - could definitely try a mixture in those "gardens"!

5 Star Nursery and Orchard
Zone 5, Brooklin, ME
Re: Pomace as understory mulch
February 10, 2021 09:42PM
One of our orchardists expressed a concern about disease load in the pommace- referring specifically to our main struggle with Anthracnose (maritime western WA). My thoughts were that through vigorous composting with wood chips that the potential inoculate would be minimized .... But the question remains, is there still a bunch of scab and antrhacnose spores embedded in our "made" compost, and will spreading that as an amendment generally serve to maintain the inoculate level.
Re: Pomace as understory mulch
February 19, 2021 09:14PM
That is definitely something to think about. I would think the reasoning behind throwing down compost over fallen leaves to help degrade them as quickly as possible as a technique against scab would be along the same lines of thinking? Composting the pomace first seems like it might be a critical step.

5 Star Nursery and Orchard
Zone 5, Brooklin, ME
Re: Pomace as understory mulch
November 22, 2021 08:59PM
Thanks to all for the comments!

As Andrew mentions, the main concern with simply spreading fresh pomace is the potential to increase the presence of undesirable spores or other pests in the orchard understory. Codling moth larvae, for example, can survive the pressing process and go on to pupate in the soil. So the simple approach is definitely not without risks. So, for me, the holistic question has become: Since we can not eliminate or control all of the factors that have potential to reduce quality and quantity of the annual crop what is the best combination of strategies in my particular orchard?

Composting the pomace first would definitely go a long way toward minimizing any negative effects of later spreading it under your trees but it does take more time and effort. Poorly composted material can actually increase undesirable pathogens in some situations so you can't be a slacker if you go that route. As I mentioned in my initial post, sheet composting (using a thin layer) of fresh pomace does result in quick breakdown and incorporation of the organic material. Whether sheet composting favor or disfavors undesirable pests likely depends on their initial levels versus the potential for beneficial organisms to out compete them under existing conditions.

Without taking the route Mike suggests of detailed observation and data collection over time you will only have a general, subjective way of evaluating if this method pays off. Then again, in any given year, weather factors and the possibilities of other pathogen triggers will complicate teasing out exactly what is going on with your soil microbiota and whether it is influencing the aboreal environment.
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