wood chips as mulch

Hey gang,
I have received a few loads of very small chips and shreds from pine and hardwood trees.  Probably more pine than hardwood.  Have been in a pile for a couple of months now.  Please, remind me:  what are the pros and cons using this as garden mulch, restrictions (if any), etc?
Thanks,

Until it has aged, it will tend to absorb nitrogen from surrounding areas. You can greatly accelerate the aging process by applying diluted urine in a sprayer. 10:1.

Until it has aged it is most useful in the compost pile or to pule onto areas like paths or weeds you want to smother. Give desireable plants some distance from fresh chips.

Fresh chips are great for growing various fungi.

Pine is somewhat allelopathic, but a few weeks composting clears this up.

Pine also acidifies the soil as it breaks down, some plants like this - particularly berries.

Hi Andy,

The chips are great for weed suppression, moistire retention, helping protect the soil biome and slow feeding the soil biome. So there really is no downfall, unless its chips from a tree species known as a strong allelopath, in which case use in places for weed suppression only like pathways.

Resurch has shown using chips as a top mulch doesn't affect nitrogen availability, except the immediate chip soil interface. That means the immediate soil the chips are touching, which is why you typically don't mix the chips into the soil. A simple layer of aged manure, slow release fertalizer or any composted material spread under the chip layer easily overcomes any concerns, if your worried about available nitrogen. Once the chips break down, the nitrogen they tied up is free, and they leave surplus nitrogen available in the soil.

As far as chips affecting pH. Depending on the pH of the chips, they may have an initial reaction altering pH to some degree, however, it's my understanding those impacts are often short lived, as the soil biome will break down and change those organic constituents leaving little long term impact on soil pH unless chips were continually applied. Since most plants like slightly acidic soil, the biggest long term change of continual application would most likely occure in and be a transition from alkaline soil not suitable for most crops, changing to slightly acidic humus rich fertile soil suitable for most crops. If pH lowering becomes an issue in humus rich soil, that's a great opportunity to add additional mineral ammendments like lime, as thats what I would suspect to be the cause, not enough minerals like calcium available for the biome to digest.

Hope that helps!

J Davis wrote:Until it has aged, it will tend to absorb nitrogen from surrounding areas.

This thesis has been disproven again and again in the research, yet it continues to be touted as a fact.  

No, wood chips do not tie up nitrogen when used correctly in gardens and agricultural settings.  N rob only happens when you bury wood chips into the soil profile.  But when used as mulch, the interface between the bottom of the wood chips and the top of the soil is so minimal, no N rob of any significance takes place.  

However, it has been shown that where fungal networks have an ample supply of carbon on which to feed, their ability to work in symbiotic relationship with plant roots to capture and "feed" nitrogen and other nutrients goes up substantially.  In other words, if you use wood chips as a mulch (not a soil amendment), it actually increases the amount of N available to plants.  If you have a healthy soil fungal network, it will begin to feed on the wood chips almost immediately.  If one does not exist, it will within 3 to 6 months if the layer of chip mulch is left undisturbed.

There are a dozen great threads on this website that document all the virtues of using wood chips in the garden.  A simple search is all that is necessary to find them.

Good luck with your projects.

I use fresh wood-chips on everything.  Most of my wood is hardwood but it's a mix of everything.

I use the chips as a top dressing, in my compost piles, or I just leave them in a big pile and let them stew until I need them.  

I can attest to the increase in fungal growth.  I have so many mushrooms sprouting it's crazy. I did not have mushrooms before.  

In a shady area, they seem to increase the amount of mossy growth also.  If you can use some bucked logs and just leave them in strategic places to rot in place it's quick habitat.  

I was out planting some seeds this last weekend and I heard a really loud ribbit.  The fungal growth, moisture retention and overall cooling of the soil has attracted amphibians.  I didn't have these before.

I have a large chipped area that I just let the weeds grow.  Then I knock them down and cover with chips.  I've noticed a quick advance from weeds I don't want to things like Queen Anne's lace.   I'm not sure if it's due to the chips, partially due to the chips or just natural progression.  

Last year I had a very large pile of Blue Spruce right next to some new raspberry plants.  These plants are twice the size of the other raspberry plantings.