Hot Composting Potato Soil

Hi everyone! I’m a newbie and I find I’m often paralyzed into inaction by all my questions. The pandemic is creating some forward momentum in me though, which I guess is a thing to be grateful for?

I’m terrified of potatoes! Which is ridiculous. I’ve gained a ton of insight by reading several of the potato posts on here but one thing I haven’t found an answer to is: if one was to grow potatoes in bags/towers/straw, what does one do with the leftover material? Of course we don’t want to waste it! If it seems that there wasn’t disease/pests, can it composted for future use in the garden? If there was disease/pests, would proper hot composting kill all that? If one left all the material in place and amended it/grew green mulch in it, could it be reused for a couple of years? Or is it just best to grow it in the ground and move it around from year to year?

Thank you to everyone for this site! I have learned so much and am so grateful for all the time put into answering questions and discussions.

Zone 6a, Interior BC Canada 🇨🇦 Pretty average soil in my newb opinion.

I hope someone more scientific answers this for you, but my understand is you don't want to grow potatoes,  tomatoes, peppers, eggplants, or root veggies for at least 2 years after potatoes in the same soil.  The reason being potatoes deplete the soil of a lot of nutrients, and even if they look healthy they can still harbor disease, and or pests.  You could grow peas beans, or some leafy greens, they should do fine.  If this doesn't work I would throw it into the compost.  If you see disease, which I hope you wont that gets a little more controversial.  I have read By hot composting, pests and diseases will be killed off by heat and microorganisms.  Not everyone agrees with this, so it is something you will need to decide.  I personally don't put anything I think has disease in my compost because I have a devil of a time getting mine to heat up. So I don't and if it doesn't heat, who cares, it still brakes down, it just takes a little longer.  What ever you decide to do, I wouldn't throw it out. When it comes to gardening I say just do it.  What is the worst that could happen?  Maybe you waist a little money on plants, or seeds and don't get veggies,  odds are you will still gain some valuable knowledge that will serve you in the future.   Good luck growing your potatoes, and have fun gardening.

Jen,

I am going to put much of what you just mentioned to the test this year.  The garden bed I just hours ago planted potatoes I call my bed #1 because it was the first bed where I grew Wine Caps.  The first year I did so I grew tomatoes in fertile holes while the woodchips broke down.  That was in 2018.  As you mentioned, tomatoes are one of those heavy feeders.  Last year in the exact same places I grew tomatoes I grew summer squash, another heavy feeder.  I wanted to see what would happen to two heavy feeders planted one after the other when growing in a condition that had an active, mutualistic fungi growing alongside.  

The result was the darkest, richest most vibrant green leaves I have ever seen.  Definitely healthier than an ordinary zucchini.  In fact, those 8 plants might have been the healthiest plants I have ever seen. I poked around at their roots and the reason was obvious—the wine caps hyphae (fungus root) was wrapped, coiled around the roots of my zucchini.  In the fall it was hard to separate fungus from plant.

It was obvious that the fungi were feeding the squash as they had done with the tomatoes the previous year.  What I have learned is that the fungi go an scavenge nutrients for the host plants.  I did also plant peas alongside the squash so that may have helped, but the zucchini was just so dramatically healthy that it is hard to convey.

This year I am planting potatoes in the same bed to really give this a stress test, but I am confident the potatoes will grow just fine.  I used to obsess about NPK numbers, particularly the N, but now I don’t really care.  I see soil partnerships as being much more important than soil chemistry.

Jen, two years ago I would have agreed with you wholeheartedly.  Today I have no problem planting heavy feeder after heavy feeder.  I will let you know of my success or failure.

Eric

Rachel,

My suggestion is to take that soil and get it back into real soil on the ground.  The best thing I can think of to do with it is to dump it on the ground and build a compost pile on top.  In doing so, all the microbial goodness in the pile will leach into the ground below.  The compost pile does not need to be particularly great, just let it sit over winter and by spring the soil beneath will be perfectly recharged, better than perfect as it will be infused with all the microbes in the compost pile as they inevitably sink down with rain.

I am increasingly amazed by just how important soil biology it to soil health.  In fact, I see the biology as being more important than the nutrients themselves.

I can give a little anecdote that may help illustrate the process.  Many years ago I had an abundance of grass clippings so I raked them and hauled them off to an obscure corner of my orchard and left it there.  The clippings rotting into almost nothing, but the following year there was an obvious dark green ring where the pile had been and the ground sloped slightly downhill towards one peach tree, the same variety as in the rest of the row.  The ring bled green downhill towards that baby peach tree which grew at least twice as tall and broad and massive as all the other ones.  The leaves were the darkest green and it is still the largest in the row.  The effects of that pile were obviously apparent for the next 3 years.

My soil under that pile and downhill were amazingly fertile for 3 years from one poorly made compost pile left completely unattended.  I no longer make compost piles outside of the garden.  

My point with this is that if you take care of the soil biology, the soil chemistry will take care of itself.

Good Luck!!

Eric

Just use the soil to grow something else or compost it.  Brassicas are a great choice, because they have few pests or diseases in common with potatoes and the isothiocyanates that they produces actually kill some of the fungal pathogens of potatoes.  Do your best to put three or four years in between potato crops in the same soil and you should be in good shape.

HI Jen,

I use a 3 year rotation of anything in the Nightshade family. It is sort of a moot point. I have about 30 raised beds in 4 rows,  so the rotation process is pretty simple. If I add a new raised bed, I normally dedicate it to tomatoes the first year.

Thank you so much everyone! So excited about mycelium also - having mushrooms everywhere is something I’d love. I’ve been learning about the positive effect they have on soil - thanks for sharing your experience and advice Eric! You too Jen!