Effect of old rotting roots on soil and new plants?

Question

I had to cut several trees in my yard for various reasons.

What happens with remaining roots of these trees? How do they affect soil and new plants planted in the same area?

Answer 1

This is by no means answer to your question but rather an observation on stumps and root removal after felling trees. Personally I'm against leaving tree stumps in the ground because you can't do much in that area and they present danger to lawn mowers or trimmers with metal blades.

There are many stumps on property I'm trying to maintain which prevent me to use lawnmower safely. Besides the fact the trees were cut down many years ago and the stumps were cut down as low as possible I wanted to remove them by any means.

Firstly, I think you would like to make sure those stumps don't re sprout which is sometimes possible. (People in my country have a nasty habit of using old motor oil for that but there are probably more efficient means).

So far I've completely removed two stumps of cherry trees (fell down at least 5 years ago) by digging them up. Bigger/thicker roots were still quite hard and it took some effort to separate them by axe. Smaller/thinner roots could be snapped by hand.

Because digging up stumps and roots is hard work, I've tried to speed up the process of decaying (although some mushrooms growing on stumps are also helping :)

I've read in several sites on the internet that faster decaying of stumps and roots can be achieved by making vertical holes in stump and filling them with high-nitrogen fertilizer which should speed up the process. In my case remaining stumps I want to remove are from evergreen trees and were still strong enough that using drill to make holes was pretty hard. Tbh, after more than 6 months of filling holes with fertilizer I haven't notice any changes in surrounding area.

I have a mixed opinion about stumps and their roots and how they can affect soil and new plants:

• In first case, you can leave them to decay at their own pace (which is probably the best option if you don't want to remove them).
• In second case, if you try to 'kill' the root system buy using herbicides (or other chemicals) there is probably some risk for new plants in that area.
• In third case, if you want to speed up decaying of tree by using fertilizer you'll probably encourage something else to grow faster.

Anyway, I have a feeling that answer on your question is probably dependent on factors like tree species, soil composition, what would you like to plant and mostly time to notice any changes.

Answer 2

For once, I don't agree with stormy, but this could also be because of my different interpretation of your "for various reasons".

I was told never to plant a tree where there was another tree. But because this is often impossible, most of the roots should be removed, and possibly a hole should be kept for some time (a winter is ideal).

This advice was given mainly for orchards, where tree are removed for healthy reason, and root diseases are one of the worst outcome (difficult to handle).

The hole: this should give oxygen, which it seems to be toxic (it is!) for many soil bacteria.

I dont't agree with stormy also about tree stumps (regarding opinion that stumps are easier to pull after several months). I still have a very hard Prunus stump (peach), dead since more than 10 years.

In any case, to plant a new tree, you need to both dig a hole and remove stump and large roots. It is better also to fertilize soil as deep as possible, so you really need to dig.

Answer 3

When a tree dies or is cut down there is a similar amount of roots mirrored of the canopy in the soil that die as well. Great organic matter. Absolutely nothing to worry about. Removing the stump and barked humongous roots are fairly easy to do using a truck and chain (shoot, I've used a Ford Escort) to pull those stumps out completely. A 'come along' would work for certain sized stumps and species of trees. Stumps are easier to pull out after they've figured out they are dead...a few months? Roots are wonderful organic matter, thoroughly emeshed and mixed in the topsoil (truly most will be 4 to 6 inches below the surface) easy to decompose and they add super tilth to the soil. I would never plant the same species of tree ever again near the area.