Thatch, Compaction and Shade

Thatch, Compaction and Shade

Part of Ep. 403 Lawn Care Special

Join UW-Madison Soil Scientist Wayne Kussow as he explores the best methods for keeping your soil and lawn healthy.

Premiere date: Jul 31, 1996

TRANSCRIPT+
Wisc Gardener Transcript: 

Shelley:
We've already talked about weeds and diseases. Common, basic soil health is also important to have a healthy lawn. I'm with uw-madison soil scientist, Wayne Kussow. How does the health of our soil effect the health of our lawn?

Wayne Kussow:
Well, a healthy soil means a healthy lawn. We need the soil for water, air and nutrients.

Shelley:
So, basics.

Wayne:
That's right, exactly.

Shelley:
I hear a lot of gardeners talk about their concerns about thatch. Is that something I have here in my yard? Is that this brown stuff? Do I need to be concerned about it?

Wayne:
Well, Shelley, if we just take a knife and scratch a little bit, you'll see all we're dealing with is grass clippings. That's no problem.

Shelley:
It's from my mulching mower.

Wayne:
You're actually just recycling nutrients and reducing fertilizer needs.

Shelley:
So, that's good?

Wayne:
That's good. But, if you do have a brown layer of stemmy material, that's thatch. That's dead stuff. If that stuff is less than half an inch don't worry about it. It's cushioning your lawn. It's helping water stay in place to infiltrate and wash into the soil. It's good.

Shelley:
So, if it gets above a half an inch...

Wayne:
Above a half an inch-- then it starts to repel water and it becomes a haven for insects and disease.

Shelley:
Then, it's a problem.

Wayne:
Then it becomes a problem.

Shelley:
What do we do?

Wayne:
Well, if it's at that point, you can just go ahead and rake it off. Or, you can rent a dethatching machine and take it off that way. If it gets too thick, the grass roots start growing in it...

Shelley:
Instead of the soil...

Wayne:
That's right. In that case, if you take it off, you've destroyed the lawn because you're removing the roots.

Shelley:
You're taking the grass with you.

Wayne:
That's correct.

Shelley:
So, then what do we do?

Wayne:
In that case, what you want to do is to try to improve the thatch as a medium for plant growth. You do that by adding soil. That gets us into the issue of aeration. Aeration is something we think about when we talk about compaction. Do you have some compaction?

Shelley:
In this yard? I wouldn't be surprised. Let's go look.

Wayne:
Ah, Shelley, this is what I was talking about: soil compaction. See how hard that surface is? There's no pores open so that the water can infiltrate.

Shelley:
Kind of like concrete.

Wayne:
Right, you've closed things off. You've destroyed what I call the plumbing and ventilation system of the soil.

Shelley:
So, this is caused by walking on it a lot, high traffic.

Wayne:
High traffic areas. And this is what we see here. Now, we've brought along a couple of tools that we might use on a small area, anyway, to alleviate the problem. Nothing more than a garden fork or a pitch fork. All you need to do is simply push it into the soil a couple of inches, rock back and forth move forward and do it again. What you want to do, is leave some holes in there so you get some water and air coming in.

Shelley:
What about this one? This is kind of neat looking.

Wayne:
This is a hand aerator. You see the hollow tubes? These take cores of soil out. If you want me to demonstrate here a second-- you can find these in lawn and garden centers-- simply push it into the soil and pull it out. See the nice holes? Tap the cores out. Simply move forward and repeat the process.

Shelley:
These work great in a small area like this. But what if it's my entire lawn?

Wayne:
If it's the entire lawn, contract with a lawn care service or landscaper to come in and do it mechanically with special machines.

Shelley:
Do they know what they're doing?

Wayne:
I would keep an eye on them to make sure they're going at least two inches deep to be truly effective. What about those funny shoes that have spikes on them? I've seen some of my neighbors use those.

Wayne:
Uh, they probably provide good exercise! The spikes-- first of all, the holes are too small. They close up so quickly that they don't do much good. Secondly, you don't get the uniform coverage that you need as you're just walking along.

Shelley:
So, something this size is more effective.

Wayne:
Exactly. But, I think you have another problem here, Shelley:. How much sunlight do you get, here?

Shelley:
About four hours.

Wayne:
I thought so. Because right here, is a classic indicator of two things. Soil compaction and lack of sunlight.

Shelley:
The lovely green moss?

Wayne:
The lovely green moss. And what happens, is you keep the soil surface moist, you don't have enough sunlight for the grass to grow so the moss comes in. Now, if you have more than four hours of sunlight, then you might try a fine fescue.

Shelley:
That would be the grass I've kind of been experimenting with.

Wayne:
Exactly. Now, if that doesn't solve the problem, then you have to eliminate shade. That means pruning, maybe taking some trees out. If you aren't willing to do that, then you're going to have to think ground covers. Hostas, for example, are an excellent ground cover in Wisconsin. Now, if you have four to six hours of sun the fescue should grow fine. If you have more than six hours, then you can start to think of the traditional kentucky bluegrass lawn.

Shelley:
The classic green lawn.

Wayne:
Exactly.

Shelley:
So, we have to decide what we're going to do with our site.

Wayne:
That's right.

Shelley:
Okay. Thanks, Wayne. So, if it's shade, plant ground covers. If it's compacted, aerate it.

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