Straw / Sheet Mulch Potato Update: SPUDTACULAR!

So its been a crazy month – I’ve missed you all!  We’ve harvested over 1000#’s of potatoes -and sold them- hitting farmers markets for the first time.  There is at least another post of stories there, but for now suffice it to say we love that we have become “the Potato People” in at least two towns and that feels great.

With the farm gardens under control again, I spent a beautiful half hour this weekend working through the Straw Mulch Potatoes that I had put in as a test of deep mulched potatoes (no updates on the towers yet – 2 of the three are still growing and the third blighted so bad I only got 3 spuds for 4 seeds planted).  The Straw Mulch bed had 10 plants, and had been sheet mulched with 3″ of horse manure a year ago, and then got another foot of straw thrown on top as the potato plants grew.  No additional fertilizer, no sprays, and not much irrigation was provided (an inconsequential 10 gallons total from washing out compost buckets).  My hypothesis was that the rich, untilled soil from the sheet mulching combined with the more constant soil moisture provided by the deep straw mulch would help tuber size and plant vigor.  On top of that I was very curious to see if there was any credibility to the claims of increased tuber set from the deep mulch, and how the harvest labor would compare.

First off, I am very pleased with the yield and am convinced (as much as one can be after one test) that super rich soil and deep mulching equates to better yeilds.  Here is my proof:

30#'s of spuds from 10 plants!!!

30#'s of spuds from 10 plants!!!

With an average yield of 3#’s per plant I would be getting 270#’s per row at the farm – a 50% improvement over my current technique – and I was already getting a solid 8.5:1 harvest ratio!   I planted this bed with 4 medium sized Purple Vikings – just under 2#’s.  Yes you got that right – a 15:1 ratio which is near record yields for even conventional farmers.

To put that another way if I can scale this technique up and apply it to my current spacing (3′ rows, 14″ spacing)  I could get 43,500#’s per acre which equates to 18,600,000 million calories.   With the blight coming in growth was stunted and overall tuber size was down compared to what I expect from Purple Viking.  One plant had over 15 potatoes on it – but only a few over 3 oz and most had 8 or more.  If those had sized up to the typical 8oz+ …no I’m not gonna run that math, I’m getting faint from the possibilities!  Sheet mulching an acre will take 400 yards of horse manure – this system isn’t for the faint of heart- but my “base” soil is deader than a doornail so a larger trial at the farm on rich soil will be on the docket for next year.

As others have found, and I have begun to suspect, there was no addition tuber set that I could attribute to the deep mulch – the spuds were located low on the vine as usual, but the soil was evenly moist and full of worms.   Harvest was a breeze, though not as easy as the bucket method – just pull the straw back,  ruffle the moist, rich soil with your fingers, and pluck our spud, after spud, after spud, after spud.  ZERO lost spuds to pitchfork foibles to boot.  As a strip crop between young swaled permaculture tree crops this could be a VERY productive system to pay the bills as the chestnut / orchard comes on line.  Plus from my experience you get a significant net INCREASE in organic matter and it is very close to no till.

Can organic farming feed the world?  Show me a conventional farmer hitting 18,000,000 calories per acre .

FU Monsanto.  You’re Round Up Ready?  Big deal…  this system is Peak Oil Ready.

Be the Change!


PS: Here is a detailed and technical study of straw mulch for potato growing in Germany.  Graphs – oooo shiny!

31 Responses

  1. That’s great, Rob. Congratulations. If I were still eating potatoes, I would adopt your technique immediately. But then almost everything does better in really good soil with lots of mulch.

  2. Rock on, potato dude!!!!!
    Potatoes were my best crop this year, which isn’t saying much, but I was happy with my yield of about 25# for 9 plants. Since potatoes are the only feasible staple crop where I live, I am putting a lot of effort into them.

  3. Thanks Ed! Agreed -Ruth Stout was on to something.

    Aimee – that is a great yield!

    The really encouraging thing here is that the soil here at our property is AWFUL – they finish grade the homes with quarry “sludge” from over 100′ down. If I can get these results on this soil, I am fairly confident that its repeatable.

    Take what ever soil lemons your property has, and in September / October lay down 3″ of manure on it, cover with cardboard and 4″ of straw and then plant potatoes in the Spring using this method and VOILA – a spudtacluar harvest!

  4. Well done you, it’s great to hear such a success story – hope someone form Monsanto reads your blog!

  5. You’re makin’ me want to be the potato guy of my neighborhood…

  6. 2500 sq ft, 1# a sq ft, and selling prices of $1.50 to $2 per pound here abouts. Its a nice little side gig.

    At the stand we try to always have a “roaster” (Carola, Nicola, or Fingerling) a boiler (Island Sunshine, Yukon) and a baker (Kennebec or Purple Viking) on the stand (and in the larder). Those little marble sized baby spuds that I threw to the geese last year? $3 a pound as a “roasting mix”. Awesome.

    Coming soon to an Ohio foodshed near you: E4’s Excelent Edibles!

  7. I tried growing potatoes with straw mulch – and lost at least a third of the crop to voles. Voles also ate probably half my beets and an entire 8′ row of carrots. They conducted guerrilla raids from their mulch hideaways on my pole beans too – nipped most of the green bean plants right off at soil level. They left me with one plant. Grrrrrr…..

    Turns out straw is an ideal habitat for the $%#$%!!beasties…that way they don’t even have to bother to dig tunnels. I think I’ll unmulch everything for the winter to give the hawks and owls a shot at the little SOB’s. I’m also trapping and have gotten 3 so far. I swear tho, they know when one of their brethren has bit the dust and won’t come near the trap in the same location again.

    • That stinks!

      Voles in mulch is one of the main down sides – especially with tuber / root crops. We had voles at the farm that we using the beets like a cut and come again – shaving just enough to not kill the beet at each feeding… smart and frustrating.

      If you have the room I suggest some large rock piles for snake habitat and to erect some raptor roosts to attract hawks and owls. We also just adopted a Jack Russel terrier and I expect to be vole free in about a year with him on the job – though he will likely do more damage than good – these dogs can DIG!


  8. Yup
    This system works for me too. If only because I actually get enough coverage over my crop that I don’t end up with a portion of them green from being too close to the surface. Hey and if we say Monsanto often enough they are sure so take note😉

  9. F Monsanto.

    What were you using as mulch? Wheat Straw? I wonder if there is a complementary action going on between the decomposing straw providing nutrients as well, especially if said mulch was an accumulator for something potatoes were particularly fond of…like say using comfrey.

    • Mostly wheat straw with some oat. I got 16 bales free from a hobby farmer cleaning out his barn. Who loves Craig’s list? This guy.

      Strange that you mention the Comfrey – post harvest I planted the bed to 120 heads of garlic, laid down an inch of comfrey and then put a foot of wheat straw back down. Figure the worms would like the Comfrey.

      The issue with Comfrey as a smothering mulch is that it is low in cellulose and lignin – meaning it breaks down VERY fast. Great for jump starting sheet mulch or a compost pile, not so much for covering the soil. I like your idea of designing a mulch for the crop – testing the nutrient levels of oat v. wheat v. corn stover v. alfalfa / clover and then mixing and matching to feed the crop. I have also though about running half the mulch through a chipper to make it more readily available to the soil on really rough soils. Good thing winter is coming with all these great ideas to think about!

  10. Love this! Can’t wait to try growing some potatoes myself.

  11. Rock on, Potato Guy! I want a comic book: Potato Guy vs. Monsanto, maybe cover art with you with pitchfork in hand…four of the five tines folded down…🙂

  12. Impressive! Thank you for posting on this technique, Rob. I may try it myself next year, as I especially appreciate right about now the virtues of a good weed suppression system. I do worry about hungry rodents though. Our elderly cat is probably not long for this world. Perhaps by next year we’ll have a new crop of young mousers to handle pest control in the gardens. If so, this technique is a definite go.

    Still hanging on for the tower report though.

    • As Rob mentioned above, stone piles or raptor roosts might invite in mousers to work the day shift and the graveyard shift.

  13. Those graphs are an eye-opener.

    I hadn’t put this together before, but keeping the soil cool through the day also means letting the air above it warm up more thoroughly. Duh. Sometimes a graph can really put things together!

    Letting the air warm up is crucial to getting tomatoes in my climate. For instance, I planted “early girl” hybrids this year, and only about half of them are ripe…it’s almost October!

    So yes, mulch seems to have a lot of effects. I’ll mulch much deeper/more often next year.

  14. How are you going to get 400 yards of horse manure/acre in peak oil times?

    • The snide answer would be that if there’s no oil, we’ll have alot more horses around – horse manure was the biggest municipal waste issue in turn of the century cities — but that isn’t realistic in the transitional phase we are approaching.

      Sheet mulching is a one shot deal to (re) build soil fertility. Also I am building up completely dead soils here in H.O.A. Suburbia – I would like to try one third this much on richer farm soil next year with a side by side of this amount.

      One horse shats about 50#’s of manure a day – about a yard every week and a half. 2 horses would provide enough for an acre 1″ deep a year. Here in the hinter lands of Greater Madison there are hobby farms EVERYWHERE looking to off load manure and will even help load – utilizing that resource to build resiliency is key. Each region will need to find their own solutions – we have lots of horses here, other area will have kelp, others cow or human manure. The key is to get organic matter back into the soil – compost, food scraps, dead cats – its all good in sheet mulch if you let it mellow a full year – less without the cats.

      Rebuilding soils (so we can grow food locally) and community (so we don’t shoot each other before we can harvest it) are two of the most pressing issues facing our generation as we work to salvage a future for our kids.

      • You really make good points in your last paragraph.

        I think that as the economy goes downhill, hobby farms and their luxury horses are going to be among the first to go. Or convert to growing food in which case there won’t be much manure left over. Perhaps its a case of getting good shit while its around.

        We’ll have to wait and see if we get spit out on the other side of transition with more horses in cities😉

  15. Have you or anyone you know had issues with the ‘killer’ compost? The manure I got this year, and the manure my friends use from their own hobby farm seems to have been contaminated with clopyralid. My potatoes and about a third of my tomatoes died, and the peppers I grew from seed are about 4 inches tall even after being in the ground all summer. They didn’t die, they just never grew. I am very leery of using manure or non-organic straw as a result now.

    • no… first I had heard of it. Sounds awful from the mini rsch I just did. Did it only affect your solanacea? Late Blight can survive in compost and dropped many of the nightshade crops in this region.

      I don’t use our municipal compost because 1) I am a compost snob, 2) its full of asphalt. But I take the raw materials from the municipal yard (bags of grass/straw/chips) all time. There is certainly a give and take with importing organic matter – I don’t use cow manure unless I know the cow for fear of the hormones / antibiotics, but I’ll take grass clippings and straw from about anyone.

  16. If you are growing more food than you need. you may want to visit – a site that helps diminish hunger by enabling gardeners to share their garden produce/herbs with neighborhood food pantries.

    The site is free both for the food pantries and the gardeners using it.

    Over 970 food pantries nationwide are already on it and more are signing up daily.

    It includes preferred delivery times, driving instructions to the pantry as well as (in many cases) information about store bought items also needed by the pantry (for after the growing season).

    If your community has a food pantry, make sure they register on

  17. I was wondering the same thing as TinFoilHat, are you having good luck finding straw that wasn’t grown with herbicide? Or horses who aren’t on a strict worming regime?
    Here’s a link about problems here in the West…

  18. […] may end up being a bust.  I’m already planning for next year.  I think I’ll do the straw/sheet mulch method. The success ratio looks good.  That, or I’ll try the bucket […]

  19. […] space constraints.  Last year I tried two separate experiments with potatoes: Potato Towers and Straw Mulch Potatoes.  The towers were an unmitigated failure, as they have been for virtually everyone that I know of […]

  20. We grow about an acre of potatoes for farmer’s market (harvested nearly 10,000 pounds this year) and although your method is interesting andplenty of people use it, I don’t see how it could be used on any sort of scale. We’re SMALL POTATOES (so to speak) and it would cost us thousands of dollars to do that over our acre of potatoes.

    • Kristen, absolutely it takes alot of doing. I am about 25% your scale (in both poundage and acreage). What I opted for was to dig a raised bed with my rotary plow that was about 7′ wide: 2 32″ beds with a path down the middle. These beds are divided by the rotary plow furrows which is a foot deep and 2′ wide. The 32″ beds each get a double row of spuds, shallow planted and top dressed with as much compost as I could spare- .5″-1″. The plow furrows were filled with wood chips that came for free from our municipality. I have also had success getting tree trimming services to deliver them for fee if you give them a spot to dump at their leisure when they are in the area. It takes 5-7 yards to fill one 100′ long furrow – this means it takes a FREAKISH amount of chips to do even a qtr acre.

      As the spuds sprout I “hilled” them with straw and leaves. We also toyed with cutting the straw in late spring from one of the 1 acre prairie plantings (3 yr rotation – 1 burn, 1 fallow, 1 straw harvest) at the farm.

      The wood chip furrow/paths stored an insane amount of water and bred massive amounts of fungus, worm, and arthropod populations. And even by harvest time (4 months) there was a noticeable layer of humus under the straw on the beds. Harvest was easier, and there was virtually no weeding so we saw significant labor savings (I harvest by hand with a broad fork). Also, yield on these two beds was about 20% better than the control, which I attributed to the fungus and microbe induced fertility and especially the even soil moisture from the mulches. Spud quality was also bed with less soil pests.

      Down side- the amount of work to fill the plow furrows is extreme – moving 25 yards of wood chips by fork and barrow took awhile. Straw was purchased and it took about 8 bales per double 100′ bed – roughly $12. I regained more than that in harvest, so its moot. But again, the labor on the bed set up was significant.

      These beds also weathered the 5″ in a night rainstorm in June that drowned my traditional plantings as the mulched furrows drained much better and there was no puddling to rot the seed.

  21. […] by some impressive results from 2009, I mulched heavily this year and was very impressed with the reduced weed and irrigation inputs. […]

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