Earthing Up Potatoes

[broadway]

Morning Folks

After helping a friend with his trees I have bags and bags of chippings. Anything wrong with me using these to earth up my potatoes?

[ameno]

Sadly, yes. As the wood breaks down, it was rob the soil of nitrogen, and will cause weak plants as a results. Depending on the chip size, the plants may struggle to grow through it, too.

Either use the chippings as mulch for established trees and shrubs, or for paths, or pile it in a shady corner somewhere, preferably mixed with something higher in nitrogen, like grass clippings, and wait for it to rot into compost.

[broadway]

Thanks Ameno

That's a shame I thought I'd had a light bulb moment

How long would it take to rot down?

[ameno]

That depends.
If they large chips and you don't mix anything with them, they could take 2-3 years.
If they're large chips and you do mix with plenty of grass clippings or similar, you may have something useable within 12 months.
If they are small chips (generally less than 5mm) then, if mixed with other stuff, they should be done within 3-4 months.

[broadway]

That depends.
If they large chips and you don't mix anything with them, they could take 2-3 years.
If they're large chips and you do mix with plenty of grass clippings or similar, you may have something useable within 12 months.
If they are small chips (generally less than 5mm) then, if mixed with other stuff, they should be done within 3-4 months.

Thanks again Ameno

I shredded them myself so they are fairly small, will mix with some clippings and see how it goes.

[ameno]

Was it the type of shredder with blades, which cut the material, or the type with spiked rollers, which crush the material?
The former produces much finer shreddings. I have one of those, and the stuff I shred is then put in the compost bin, where it completely decomposes within 2-3 months.

[broadway]

It was my mates so not sure, will get a photo of the shredding tomorrow, they are bagged up at the plot

[SarrissUK]

Yeah, I agree with Ameno. Nitrogen robbing is definitely a thing. I used some horse manure last year that was mixed rotted and fresh (the woman owning the horses kept chucking fresh on top of the old) and it very very noticable difference between the areas that had only rotted manure, and those that had a mix of fresh. The plants were there, growing, but slowly... and never really took off.

[TrialAndError]

Recent research has shown that adding mulch, inclduding wood chip, has almost zero effect on robbing soil of nutrients including nitrogen. In the top 1cm of soil it does have a minimal effect but below this, where the roots are sourcing their nutrients, the effect is zero.

Add those chippings, they will deter weeds, retain moisture and rot down providing slow release nutrients. #

[SarrissUK]

Links to that research would be interesting if you have them. Squashes and courgette roots are fairly shallow considering the size of the plants and they were really struggling in the manure with fresh stuff mixed in. Two metres away it was all well rotted, and the same varieties were thriving.

[ameno]

Recent research has shown that adding mulch, inclduding wood chip, has almost zero effect on robbing soil of nutrients including nitrogen. In the top 1cm of soil it does have a minimal effect but below this, where the roots are sourcing their nutrients, the effect is zero.

Add those chippings, they will deter weeds, retain moisture and rot down providing slow release nutrients. #

Which is why I suggested using them as mulch for trees or shrubs.
They're no good for veg, though, because they won't rot with one season if used as a mulch, and even in a no-dig system, a certain proportion of them are bound to end up getting mixed in with the soil as you remove old plants and plant new ones.
And using them to earth up potatoes is especially no good, as the potatoes will be growing in that layer.

Links to that research would be interesting if you have them. Squashes and courgette roots are fairly shallow considering the size of the plants and they were really struggling in the manure with fresh stuff mixed in. Two metres away it was all well rotted, and the same varieties were thriving.

That would have been a different problem.
Manure doesn't rob soil of nitrogen. Quite the opposite, in fact. Manure adds nitrogen to the soil, and fresh manure has too much nitrogen. This forms nitrate and urate salts which burn plant roots. Fresh manure is also very bacterially active, which can also be harmful to plants (not to mention us).
That's why you need to leave it to rot first. The bacteria feed on the nitrogen compounds and the excess is given off into the air, reducing the nitrogen content to levels no longer harmful to plants. And once the excess nitrogen is gone, the bacterial activity slows right down, too.

[Spazturtle]

From: https://s3.wp.wsu.edu/uploads/sites/...wood-chips.pdf

Concern: Wood chip mulches will tie up nitrogen and cause deficiencies in plants.

Evidence: Actually, many studies have demonstrated that woody mulch materials increase nutrient levels in soils and/or associated plant foliage. My hypothesis is that a zone of nitrogen deficiency exists at the mulch/soil interface, inhibiting weed seed germination while having no influence upon established plant roots below the soil surface. For this reason, it is inadvisable to use high C:N mulches in annual beds or vegetable gardens where the plants of interest do not have deep, extensive root systems.

References are not in the PDF due to the number, they are here if you want to go though them: https://puyallup.wsu.edu/lcs/reference-wood-chips/

You can read all of Dr Linda Chalker-Scott's debunking or confirming of gardening myths and rumours here: https://puyallup.wsu.edu/lcs/

[ameno]

For this reason, it is inadvisable to use high C:N mulches in annual beds or vegetable gardens where the plants of interest do not have deep, extensive root systems.

No good for potatoes. Or any other veg.

[Penellype]

Yeah, I agree with Ameno. Nitrogen robbing is definitely a thing. I used some horse manure last year that was mixed rotted and fresh (the woman owning the horses kept chucking fresh on top of the old) and it very very noticable difference between the areas that had only rotted manure, and those that had a mix of fresh. The plants were there, growing, but slowly... and never really took off.

That's interesting. I grow some crops (lettuce, spinach, beetroot, melons) in 100% fresh horse manure topped with about an inch of new MPC in my hotbeds and I've never had a problem with growth.

This is my spinach in the hotbed on 1st June last year:

[broadway]

Picture Of Shreddings.

Hello Ameno

As discussed here is a picture of the shreddings I have, the size varies but not much.

Can I put these in my normal compost bin along with paper and my kitchen waste, I must admit I have more kitchen waste than anything else so my assumption is the shreddings will help even the balance?

Given the amount I have I think I'll also do a couple with just shreddings and glass clippings.