Growing Potatoes to Feed the Soil

I often find that I learn a lot, or gain significant
insights, when things don’t work as I expected them to, especially when something fails. While digging out this crop of potatoes in
the Black Plot I became quite disillusioned. I wasn’t expecting a great yield for a variety
of different reasons but as I dug them out, I realised that things were worse than I expected
them to be . Although I was digging up a lot of big potatoes,
many of them were riddled with slug holes. I have had a lot of slug damage with my potato
crops in the past, and it remains one of the persistent pest issues that I am trying to
deal with. As I continued to dig out the long rows of
buried tubers, I began to notice that there were a lot of earthworms – more than usual. The presence of earth worms is a good sign,
as they are highly beneficial to soil development. The general idea is that the more there are,
the better and healthier the soil is, or will become. I would expect there to be a fair number of
earth worms in this soil, as it had been turned over in the spring, burying a lot of organic
matter which would have provided a lot of worm food. But there seemed to be more worms in this
section of the soil, than in other parts of the plot that had received the same treatment. Then I noticed an interesting correlation. In parts of the bed where more of the potatoes
were eaten by slugs, there were more earthworms. And in areas where there was less damage there
were fewer worms. It was only then that I realised what was
probably happening here. The potato plants were storing huge amounts
of carbon in the form of starchy carbohydrates in the underground potatoes. Slugs were consuming some of these potatoes,
and the worms were feeding off of the wastes from the slugs, either directly or by consuming
the bacteria and fungi that fed off of the slug wastes. This is a simple but effective food chain,
funnelling huge amounts of food to the soil biology, with the potato plants acting as
primary producers, and the slugs acting as primary consumers. Of course, I would much rather harvest a full
crop of slug free potatoes, but the loss of a crop is not a total loss – it never really
is in a garden. The potatoes that won’t be feeding me will
be feeding the soil, and this increased soil biology and fertility will only benefit the
next crops that I plant in this part of the plot. Potato plants are extraordinary for the amount
of carbon they can pull out of the air and sequester as carbohydrates in the tubers. This is why we grow them. But what is food for us, can also be food
for the soil biology – and in this case there is lots of it. I started to wonder if potato plants can be
used as a green manure. Green manures are plants that are specifically
grown to build soil fertility, to fix nitrogen, to improve soil texture, and to increase soil
organic matter. A important role of green manures is to feed
the soil biology by putting carbon into the ground, and that is exactly what is happening
with part of this potato crop. So, I began to think about the idea of planting
a crop of potatoes with the purpose of leaving them in the ground to feed the soil. If enough slugs were around as primary consumers,
it seems that a lot of food could be supplied to the soil ecosystem, including the worms. This would really benefit the soil structure
and the crops that grew in that soil in the following seasons. But, the slugs that ate the potatoes would
only go on to make many more slugs, which is not a good thing in a vegetable garden. Unless you had something that ate the slugs,
like ducks. Now that could be an interesting integrated
approach that would be worth exploring at some point in the future. Another issue is that potatoes that were not
eaten by slugs could sprout again in the following spring, which would be problematic. Beyond becoming a persistent weed within the
next crop, these second generation potato plants could become a source of potato blight
to infect next years’ crops, which is definitely something I want to avoid. Overall, it is probably not a great strategy
for my gardens, unless I could find a way of killing off the slugs, having them eaten
by something, and to make sure that all remaining potatoes were removed. But I am intrigued by the possibilities of
using potatoes, and even other crops, to actively feed the soil instead of providing a harvestable
yield. From this simple observation about the number
of worms corresponding to the amount of slug damage, I realised the positive impact that
this could have on the soil. In hindsight this now seems rather obvious. I have read about these type of soil processes
in books, and understand the basics of what is involved. But, as with many things, it took direct experience
to make that knowledge my own, rather than simply relying on the experiences and teachings
of others. So, I decided to find out how many earth worms there actually were among these slug eaten potatoes. I dug out about a quarter of a square meter
of soil – about two and a half square feet – from around one potato plant that had had
moderate slug damage. I counted 85 worms in total, and there would
be significantly more worms around the plants that had had more slug damage. As most of them appeared to be immature common
worms, it would seems that their population has substantially increased quite recently
– which makes sense with all of the extra food. This number of worms translates to more than
300 worms per square meter – more than 30 per square foot – which is apparently at the
high end, or the upper end of what I should expect to find in healthy organic soils. So, inadvertently, the soil in this part of
the Black Plot is off to a good start!

70 thoughts on “Growing Potatoes to Feed the Soil

  1. this is the first channel that I've subscribed to with this few current subscribers, the main reason is that I enjoy your method of teaching, simply asking questions, without giving a defanate yes, or no answer. I find it very refreshing and enjoyable to watch these videos, Please keep up the good work.

  2. I wonder is there anyway to reduce the lightly-hood of Slug damage to potatoes ? Maybe digging the soil before planting and putting some chickens on the freshly dug soil to eat the slug eggs that would be present in the ground . It's terrible when you dig potatoes and discover slug damage , I like your positive attitude .–Great video .

  3. every raised bed I build I plant potatoes for this very reason the first year, as well as legumes of some sort to fix nitrogen.

  4. Yes, I agree potatoes by definition are a great cover crop like tillage radish. They break up compaction. I also found a healthy amount of fat earthworms and families nearby. The potatoes provided a great habitat for the earthworms. While digging my soil I discovered a "rock layer" so I removed as many rocks as possible and replaced that layer with coffee grinds, newspaper, and hay. I enhanced the earthworms habitat. If I move my potato plot around my garden and do this every year I will reap great benefit:)

  5. Great lateral thinking and observation. I've just subscribed to your channel. I like to hear people think out loud and make connections like this. Great channel and thoughtful presentation.

    Many thanks

  6. could you use a rotervator to mush up the potatoes in the ground so they don't sprout and possibly nourish the ground more effectively. regarding the slugs I like the idea of ducks, they will fertilize the ground and produce eggs using the energy from the slugs. Love your thinking and methods. j

  7. Boah… da läuft es mir echt kalt den rücken runter!!!
    This isn't nice to look at… Wow… I'm really way to squeamish for dealing with worms and slugs. Luckily my husband is great with this kind of work 😀
    Thanks for the imput! 🙂

  8. In a small garden you could perhaps put som cardboard and straw on top of the potato bed in early spring. And grow a non root-crop later in the year?
    Perhaps that could prevent the potatos from sprouting?

  9. Hi Red If you have not already check the channel (I am organic gardening) he same great stuff there on green manure… Enjoy and thanks for sharing info…

  10. what is the best garden style would you recommend for semi beginners….polytunnel no dig ,etc …PS love the great content man very informative out of the box content

  11. Goodness! That is a lot of worms!!! I have had good success with slug control by placing shallow bowls into the ground and filling them with beer. The slugs crawl in, being incited by the yeasty sugary smell…then they drown.

  12. Soil feeders…comfrey, yarrow, milk weed etc. I also use aloe vera as a ground cover to reduce the need to use the weed eater around the wicking pots.

  13. consider diversifying your crops in each bed. Rather than having 100 potato plants, try 20, mixed in with 5 others. this will have control insect outbreaks. overall, a very thoughtful video.

  14. It's a common cop out for gardeners (even myself) to say its fine to lose a crop because it feeds the soil.

  15. I've seen videos and talked with people that purposely or through happy accident used chickens or ducks for pest control. With Chickens I've heard/seen them being used to diminish the populations of fleas, ticks, whatever kind of worm follows cow poo, moles and coral snakes in South America. With Ducks I've seen them used to control the populations of snails for a vineyard… that's it. I'm sure ducks have other good qualities though. Moving on.

    My Mom a while back discovered something with Japanese beetle traps; they made the beetles come to her. The killed a lot sure, but more were attracted to her garden then before she got the trap. However, if your neighbor a few rows down got a trap suddenly you had no Japanese beetles! So, my suggestion is you treat your potato field as the center of a clock. Put a group of chickens/ducks with your potatoes to eat the slugs that show up early morning. Put your beer traps at your 12 o'clock or 6 o'clock, an area without crops but nearish enough. Rotate your chickens/ducks from center of clock to 12 o'clock and put your beer traps at 1. Rotate each day with chickens following the beer with a portion of your chickens/ducks stay with the spuds. It could be before the slugs die the death of beer drowning the lay their eggs. Attracting more slugs to the area then you can kill with the beer traps while allowing them to have progeny before can be killed.

    A mobile chicken coop would be helpful for this. My understanding is ducks are easier to heard so you might be able to just ask them nicely.

  16. About the green manure question – at what stage in in potato growth do the slugs move in? Can you "chop and drop" the the potato leaves before the slugs move in, and potentially provide both carbon (potatoes) and nitrogen (potato leaf much) to the soil?

    Sorry, it's in french, but according to this person, he said that fighting slugs is useless, and harmful on the long run.
    He said that most species of slugs prefer dead and decomposing vegetable matter to healthy ones, but when they don't have much to eat, they target stressed plants (mostly transplanted ones), and he advice to use platisc bottles to protect young seedling.
    And he said that using mulch will divert the attention of slugs, and that slugs play the same role as fungus and to reduce slugs you have to encourage fungus development (digesting decomposing matter).
    btw, he does the composting on the beds under hay mulch instead of straw.

  18. Chickens are awesome slug eaters and they also make lots of nitrogen. Particularly the Barred Rock breed of chicken love slugs

  19. Wondering about a potato cover crop as a good way to initially create a perennial food forest. Seems like it'd be great for planting fruit and nut trees into the next season, though I don't know anything about slug tendency to damage young trees. They didn't touch the apple tree I planted last year in a bed where they were demolishing kale on a daily basis, so maybe it could work. Imagining a nice hazel scrub, more and more food every year

  20. I started to provide habitat for frogs and toads in my garden and really encourage them to stay. I hardly have a slug problem anymore. Nature always has a solution.

  21. Hi there, but what part of your food chain is just your speculation or actual science? If its just speculation, then please say "I think" before you begin to tell us about your garbage opinion. Thanks.

  22. Great stuff. I'm impressed about your knowledge based on your incredible observation skills.

    I was wondering if you ever try or are aim to make a video about using Biochar in the garden. It would be great to hear your pros and cons about it.

  23. My 2 cents from Canada. I'd put down some boards between the rows slighty elevated with stones or whatever. Then in the morning flip over the boards and pick off the slugs. After a short while you should have the slug situation under control.

    Sometimes the simplest solutions are the best.



  24. Here's a slug experiment using coffee grounds as a deterrent. The best bet would be to visit a coffee shop and ask them to save their used coffee grounds for you.

  25. OK…here's a few other slug control methods which might help.

  26. I've just tried growing spuds ontop of cardboard and covered in wood chips and there is no slug damage! the cardboard has disintegrated but there are no slugs either, I shall leave them in a little longer as the foliage is still green

  27. My garden is situated on an old industrial potatoes farm sandy soil with poor nutriment.
    Its really difficult to restraint the water into the sand but ill try the straw bed.

    Do you have a natural "green" trick to rebalance the nutriments ? We dont have much slug here in Québec Canada ( in my sector ).

    I love the idea of using plants and crops to rebuild soil.

  28. Think of those potatoes eaten by slugs to be like a mouse trap or in this case >>> a slug trap.
    Grab those slug-eaten-potatoes with the slugs and dump them all in container of water. Let it sit for 3-4 weeks (until the potatoes decompose in water and slugs dead) and you can water it back to the garden. It stinks like hell, but your soil will love it.

    I once was dismayed that my womboks were eaten by earwigs… Then I grabbed the womboks with the earwigs and put them into a water filled container. Earwigs dead and free fertilizer for the soil 🙂 >>> earwigs trap.

  29. I am growing spuds in my front garden in a wet climate in the U.K. so far I have just used 2 or 3 garlic cloves blended well in a bullet and then diluted & added it to water in my can. I don’t use chemicals because I have frogs in my back yard. Apparently slugs nervous system and mucous are affected by the oil in the garlic, I shall see what happens when the tops die off what’s left !

  30. Wow! that was a lot of slug damage 2 years ago when you posted this video. Are you still having slug problems ? Without encouragement, I have found a few frogs in my garden over the years and have had very few slugs. HGV.

  31. Very good information. Thank you for sharing your knowledge. I just bought some organic potatoes to plant and looking for ways to avoid slug damage. I might just grow in buckets due to space considerations and also slugs…I have observed sheet mulching with cardboard tends to attract also…🐌🦆🍻🍻🌈🤙🍻

  32. Why not put slug snail poison on plastic dishes .
    The go for it like mad and die on the spot .
    Ducks and chickens will trample and devour some crops .

  33. Do radishes store airborn carbon like potatoes? I was thinking of planting a few types of radishes to improve the soil as a cover crop this fall.

  34. I don't have a slug problem (plenty of other pests!) but like to grow potatoes with a form of sheet mulching since they do well in compost/leaves, etc. Always happy with the soil quality after harvesting.

  35. It sounds to me like it's keeled slugs, Melacidae… possibly Sowerby's or Budapest. Fond of eating roots and root veg and live underground. These might be of interest – section on potato varities more/less susceptible to slug damage in there and which has a really good indentification section in it. A glance at wiki tells me that in the UK, the budapest slug juveniles hatch out in April or May – but it's only Sowerby's (Tandonia sowerbyi) that has Ireland in it's Distribution list on wiki – you may need to catch a couple (guide on slugwatch, yeet!) to identify which you have in the black plot – may be a few varieties in there.

    The nematode route would seem to be the most sensible – but I see from reading the comments that you've tried that method and it didn't seem to have much impact. My immediate thought on the nematode route, after reading about keeled slugs, was how to get a decent penetration of the nematode-rich water deep enough? Perhaps drilling the beds to a reasonable depth (1-2 ft?) at frequent intervals before dousing with the nematode solution sometime in Spring would do it?

    A squadron of ducks or chicken brigade would be much more fun! Best, Ellie 🙂


    How often do I water potatoes and garlic here's a link to what they look like I just made a video.

  37. Just the roots alone contribute a lot to the soil. You need to try the Ruth stout method of growing potatoes. Also beneficial nematodes may help.

  38. Fascinating. I too, have loads of earthworms, and also, loads of slugs. I don't use Sluggo because I know it will also act against the worms. Right now chickens and/or ducks are not a possibility (waiting for ahem, Someone, to fix the fence…) What are your next steps? Is it easy to have earthworms WITHOUT slugs? Thx.

  39. I found that slugs love Dyer's Woad (Isatis Tinctoria) more than anything else. They even leave the salad alone for it.

  40. i never seen so much damage by slugs..we ( in the Netherlands) have those little slugs as well but they don,t attack the tubers, only a very little damage acure..
    maby bring back peelt tubers back in the ground so the will not sprout again..

  41. Great video ! I've been seeing a lot of organic indoor gardeners feeding their worm by slicing fruit in half and placing the cut on the soil. Rotten fruit from a forgotten orchard could become a great resource

  42. How do you look at a loss and go full ecologist on us and don't even give a damn because you can see the long term benefits.

  43. Fantastic optimism for an initially frustrating find. How about an organic application of mould spores that feed off of potato tubers (If such a thing exists) or now the potatoes are above ground you could top dress them with fresh grass clippings to create a linear compost pile, this would complete the food web cycle whilst both removing the potatoes and not harming the beneficial organisms? You could then when the compost piles have cooled a little breed up a huge tub of nematodes to finally infect all the slugs….

  44. Why don't you just harvest the bad potatoes, run them over with a lawnmower, mix in water, pour it back over the field , then stick some sheets of cardboard over the field so you can easily collect huge portions of the slug population and dispose of them?

  45. Adding all male moles they cant reproduce and die out eventually. Bury Broken pieces of potatoes that WONT sprout.

  46. I never relived how much slugs were a pest in gardens until I started watching you. Just a neat random fact for someone who doesn’t grow stuff in gardens. 🙂

  47. Have you considered the reaction slugs snails and worms have to heavy rain? By placing out traps in the rain, these things will automatically come to the surface and try to find a sheltered pl. This could help you recognize the opportunity to cull the slug population and leave the worms.
    Also slugs love to drown their sorrows in stout beer.

    We use rain to give the chickens a bonus of their favorite food. We bring the slugs to the chooks and a friend eats the snails. This saves the worm's from being supped on

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