Wood chips, nitrogen, veggies


I’ve seen numerous discussions on here regarding wood chips, the best friend my soil, better known as “sand,” has. This article was really interesting to me as it validated my anecdotal evidence and addressed why there isn’t a huge amount of research on the topic. The conclusion, top dressing with woodchips, then tilling under, is really beneficial in building rich soil.

My current garden regimen is to top dress with chips, then over top that with leaf litter. By fall, the woodchips are ready to get tilled under. Wash, rinse, repeat. In the orchard… I’ve been top dressing with chips only. Places where it’s been turned under are looking great. Places where it hasn’t been turned under look like woodchips.

Happy reading!


tilling in chips has really loosened my clay soil also. there is tons of worms in there. in places like around my trees, where i just top dress every spring, there is about 4-5in of black soil on top. i also add chic bedding and comfrey leaves before putting down my chips in early summer. everything is growing fantastic! i also mulch my raised beds lightly and allow the seedlings to grow thru the chips. i mulch heavier in between the rows to keep weeds out. in fall it all gets turned in the soil and gone by spring.


That is really interesting. I’m a big wood chip guy, but never turned them under. Guess I have another experiment on the books now.


Very interesting!
What I don’t like about this is that woodchips application seems to lower pH. If one compares pH in standard plots (7.2) to the plot with woodchips (6.8)…I don’t like this. We already have very acidic soil, at about 5.5…


It used to be claimed by authors of articles on composting that no matter what your native pH was, organic matter would serve to buffer it to a more neutral level. I do not know whether there is any truth to that but somebody else might.


Even if the ph drops a bit, that’s more easily remedied with lime than the other work I’d have to do to achieve the benefits from Woodchipping. For someone that’s starting with rich, healthy soil, the story may be different.

I think it’s time for another soil test.


mines at 6.0 but in 5 yrs of mulching with wood chips i haven’t noticed any issues. just sprinkle a little lime down every few years. it will keep the ph from getting too low. i ground my eggshells fine and use that occasionally. it works more slowly though.


just make sure they have aged with ground contact for at least a season before tilling or they may rob N. some people spread some blood meal on the chips before tilling to ensure the chips break down completely.


I don’t have wood chips per se, but when I clean my chicken coop I use the pine shavings bedding as mulch wherever I happen to have a bare spot in the garden. I don’t till it in, but it breaks down eventually and the chicken manure takes care of any nitrogen deficit. I’ve been doing this for over 10 years now, and I had validation that my system is working when one of my friends came over to help me in the garden and asked, “How do you have real soil when we just have sand?”


Aged composted wood chips are great.


A neighbor mulched one end of his garden with wood chips a few years ago and planted corn. It was like looking at a staircase with tall healthy corn at one end and yellowed 3 ft tall stalks at the mulched end. I told him to put about 20 pounds of ammonium nitrate on the mulched end. The stalks then grew to nearly normal height and produced decent ears of corn.

Always use a nitrogen source to help wood chips break down if you intend them to build up your soil. Otherwise, I could not agree more. Wood chips are an excellent soil builder. Chicken manure is a very good way to add nitrogen so they break down properly.


i mulched for 3 years every spring with no fertilizer at all and i got the opposite results. could it be your neighbor mixed some mulch into the soil before planting or had poor soil in the 1st. place? the only way mulch can take N out of the soil is if its been mixed in , other wise the only place top mulched soil loses N is on the soils surface where it touches, which doesn’t affect the N below surface contact. matter of fact if you add fresh mulch every spring, last years mulch has broken down releasing N which helps break down the fresh stuff. same happens on a forest floor i agree adding N to the mulch will speed up the process and fertilize more than just the stuff that broke down from last season. I’ve used chic manure and all my plants took right off. i even put a light mulch over my seeds after planting in my raised beds. once they grow up though the mulch , i hit them with a little compost tea. its usually enough to get it through to crop. in fall i add a little blood/ bonemeal and turn everything in. by spring its all gone and ready to plant again.


He mixed some into the soil and put a layer on top as well.


I will confess to having tilled under and top dressed at the same time. The nitrogen issue is short lived and the benefit of a massive influx of organic matter seemed well worth it. Also, I was only cover cropping at the time and didn’t have to worry about yield, etc. At the end of the day, in my case, the added moisture retention outweighs the nitrogen issue, even in the short term. (Initial soil analysis rated my soil as ‘mineral’ with negligible organic matter.)


if you have a rich soil and your mulch is fairly fine you probably won’t even notice the difference.


I’ve done a lot of study of applying wood chips recently to my hobby orchard and my garden. The information below is from my personal experiences and the “back to eden” tours on YouTube (by Paul Gautschi). Mulching with wood chips is AWESOME as you don’t need to fertilize your trees, the mulch holds in the water so very little if any is needed, plus very few weeds grow, and those that do are easily pulled out by hand. However there are a few vital points to make wood chip mulch work:
1/ NEVER till the wood chips into the soil. They rob nitrogen from the soil and plants as they break down if you do. 2/ If planting in a garden with wood chips, always plant the seeds in soil UNDER the wood chips, with the wood chip pulled away in a furrow. As the plants grow from the seeds you can slowly move the chips back over the stems of the plants. If you plant the seeds directly into the wood chips they start to grow okay, then shortly thereafter stall out and turn yellow, again due to the nitrogen being taken by the decomposing wood chips. 3/ I have had great success covering lawn grass with construction paper (available at Home Depot, cheap in big rolls), put a layer of grass clippings or composted cow manure over the paper and under the wood chips, and by next spring the original grass dies, composts, and feeds the plants. No need to do all the hard work of removing sod around fruit trees! 4/ Wood chips are a LONGER TERM solution. Don’t expect immediate results similar to putting fertilizer onto trees/plants. I’d say each year gets a bit better, and the maximum benefit doesn’t hit until about the 3rd year. The area where the wood chips touch the soil is where all the “action” happens, so if you put any kind of “plastic weed fabric” in this area you are defeating the purpose. Only use construction paper or cardboard, both of which degrade shortly. You do need to add more wood chips each year as they compact down as they compost at the soil level. But no more watering, no more fertilizer, and very little if any weeding, and super healthy and productive fruit trees is the result. And each year gets better and better! The soil becomes alive and you will not believe the numbers of fat, healthy earthworms under the mulch and how much the soil will improve. The best time to do this is late fall, just before winter/snow sets in. The melting snow the next spring gets things going well with this mulch. You can add a bit of lawn clippings, cow manure, fall leaves, etc. to the wood chips as this helps break them down if you want to. But all in all, no rush, its a longer term project with great results I find.


Adding an observation… This may not be true everywhere, but here, with 10-15 feet of snow per year, chips applied in the fall make much better contact with the soil than chips applied in the spring. All of the advantages above are enhanced.


I tilled my chips in 4 years ago when I had the garden moved 15 feet. The first few years nothing would grow and last year a little growth but everything lacked nitrogen so I added Horse Poo, spent Coffee and my homemade compost. This year the growth is much better and we are getting some veggies but the garden is not yet “taking off”. Maybe next year.


I will repeat myself here. If soil has poor drainage, woodchips right on the surface are capable of competing with plants for nitrogen. This is likely true on years with very high rainfall and cool weather on soils with decent drainage.

It’s important to realize and very difficult to embrace the fact that the variabilities in horticulture make all recommendations uncertain.


Climate plays a huge part. Wood chips break down relatively fast here in the hot humid southeast. The faster they break down, the more nitrogen they sequester. You can bet that nitrogen tied up in wood chip decomposition is NOT available for plants to absorb. I suspect there would be fewer problems in a colder climate.