soil structure question

[murphy4trees]

I recently planted a row of white cedars at my house with the guy who grew them, an old nurseryman.. I used the stump grinder to dig the holes. He thought that the plants would love the fine loose soil from the grinder... I wonder though...

I remember taking a course on soil chemistry many years ago, which talked about rototilling harming soil structure by braking soil up too fine. I think the stump grinder does even worse... Next time it rains hard, that soil all turns to mud and then hardens up... Does that make sense?

 

[NeTree]

In theory, I can see the relevant point. How much it matters in actual practice would have alot to do with the initial soil composition. Know what I mean?

 

[Guy Meilleur]

Originally posted by murphy4trees
rototilling harming soil structure by braking soil up too fine... How much it matters in actual practice would have alot to do with the initial soil composition.

Erik's right; if there is adequate mineral and organic stuff then it should be ok. Peds (the little chunks in there) should re-form, if there's a lot of biological activity.

Breaking up too fine is a legitimate concern, but you need to look with magnification to see what's really going on in there. Stumpgrinders leave a pretty fluffy soil behind; they aerate more than a tiller.

Make sure your roots are spread out and not circling, and that they set on something solid. As soil settles, trees will too, and can wind up too deep even if planted flare at grade.

 

[Frans]

Augers, shovels and even stump grinders all can glaze the edges of the planting hole so make sure this does not happen or break up the sides of the planting hole.

"plant wide not deep", and "$200. hole for a $100. tree"

"Next time it rains hard, that soil all turns to mud and then hardens up"
Mulch, Mulch, Mulch

Frans

 

[Nickrosis]

The real harm is done when it happens repeatedly. In many natural instances, soil is disturbed and recovers. It wasn't until farming where soils were repeated disturbed in the same way year after year. Farmers eventually learned the value of crop rotation and fallow years, but the best option (from a soil standpoint) is to have a minimum amount of disruption.

Growing grass and walking on soil is disruption enough in many cases to warrant remediation. It doesn't just require a bulldozer's worth of damage.

 

[ORclimber]

Originally posted by Frans
Mulch, Mulch, Mulch

Like this?

 

[Nickrosis]

Volcano

Originally posted by ORclimber
Like this?

Is that Mount St. Helens?

 

[Tom D. Wilson]

watch out for dog puke fungus.

 

[M.D. Vaden]

In my estimation, breaking soil into pieces smaller than 1/4" would be damaging. But if it remains bits and pieces, it should be okay.

You won't be tilling, but I recall watching a landscaper prepare a lawn across the street with a tiny Mantis rototiller. The guy had to go over the area so much, it was like dust.

Just one example of why it's better to use a more powerfull rototiller with less passes.

Stump grinding dry - real dry - soil, tends to do far more structure damage than grinding in soil that is moist. Grinding dry soil pulverizes it into dust.

 

[Guy Meilleur]

Originally posted by M.D. Vaden
I recall watching a landscaper prepare a lawn across the street with a tiny Mantis rototiller. The guy had to go over the area so much, it was like dust.

MD, I use a Mantis for preparing tree beds (not lawns no way), and it works great at breaking up the clay. I'm usually adding old pinebark and gravel fines to retain structure.

The clay is so hard to start with that it never gets too fine, at least as far as I can tell by the results. That Mantis is a real back saver on making tree holes, and I do use a reartine on big areas like you suggest.

 

[Guy Meilleur]

Originally posted by Mike Maas
I heard a guy say not to add sand to clay, because then you've made concrete.

That can happen. the key may be to add coarser textured mineral, not too much of it, and with OM to prevent concretization.

 

[Frans]

wadda bout adding Gypsum?
Frans

 

[Guy Meilleur]

Originally posted by Frans
wadda bout adding Gypsum?
Frans

Great stuff for busting up clay.