Topdressing / admendments

[dylan]

With all the recent discussions on topdressing and such I was wondering if anyone would like to explore the different types of soil admentments available to us. For example: compost, sand, topsoil, sawdust, and ground up wood chips. Maybe list of pro's and con's of each.
Using wood products is new to me but sounds interesting for building long term om levels.
Does the sawdust filter down into the grass / aeration holes or mat up if it gets wet?
How does the sawdust / wood chips affect seed germination?
Would it benefit to combine sawdust with topsoil/compost?
How many cu yds / 1000 sq ft of sawdust would be optimum?
Are you using a topdressor to spread it or a blower?
Where would you buy it in large quantities?

[jkelton]

The major problem I see with using wood chips and/or sawdust is the fact that decomposing wood will take away nitrogen from the soil as it decomposes (very high C:N ratio). Depending on what you are putting the topdressing on (cool season grasses or warm season), the topdressing materials will be different. I am assuming you definitely have cool season grasses in your area, so compost would be better that a sand-based product. I am using a blower truck to spread a high quality compost in my area and I have had very good results so far. I know of a blower truck company in your area that provides a very good product if you do not have a contact for that service.

[dylan]

Sounds interesting. Got a name and number?

[jkelton]

I have their website address:

http://www.landsourceorganix.com/

I had a chance to talk to these guys a little over a year ago at a blower truck convention - they really have done a lot of work in this area (in regards to using compost). The guy I talked to was Rick Buist and he was very helpful in providing information to me.

[Dchall_San_Antonio]

What jkelton said about sawdust robbing nitrogen from the soil only applies if the sawdust is tilled into the soil. If the sawdust is applied as a mulch or a light dusting on top of existing turf, there is no way the microbes growing in the sawdust can reach out into the soil and steal nitrogen back into the sawdust. And if you have sawdust already mixed in your soil, the nitrogen is not robbed, it is borrowed. As the wood rots, the nitrogen is returned to the soil.

My normal suggestion for compost should apply for any bulk organic material applied onto existing turf. One cubic yard per 1,000 square feet is a safe amount to apply at one time without smothering the lawn. Even then, the material should be swept off the grass blades and down into the soil. I use a pushbroom on my little yard, but even a leaf blower would work. Anything that drags across the grass would work. Rakes are way too much hand work for this job.

This rate can be applied every week if you have a need.

[Dchall_San_Antonio]

compost, sand, topsoil, sawdust, and ground up wood chips

Compost (I'm thinking of excellent decomposed manure that smells wonderful)
Pros:
1. resupplies a huge spectrum of beneficial microbes (bacteria and fungi) to the soil.
2. acts as a mulch to shade and hence retain water in the soil.
3. provides a poor quality of protein to the soil as a fertilizer.

Cons:
1. Cost. Far and away this is the most expensive organic material on a per square foot basis.
2. Bulk and weight
3. No easy way to spread - labor intensive.


Sand
Pros
1. acts as a mulch to shade and hence retain water in soil
2. low cost
3. drains well
4. provides a good root holding medium
5. sand topdressing has an undefinable way to stimulate new growth in some plants and grasses

Cons
1. provides no nutrition
2. in the absence of organic matter, sand mixes with some clays to form a very firm material often likened to concrete. Of course real concrete requires cement as a hardener, but the sand/clay mix is often very firm.


Topsoil
Pros
1. usually cheap
2. acts as a mulch to shade and hence retain water in soil
3. provides a good root holding medium.

Cons
1. often weedy
2. often the poorest of local soils, even subsoils


Sawdust
Pros
1. acts as a mulch to shade an hence retain water in soil
2. provides a base for introducing beneficial fungi to an otherwise fungally depleted soil.
3. Cheap

Cons
1. not widely available in bulk
2. contamination with CCA treated lumber dust is an organic nightmare (voice of experience)


Wood chips (from a chipper wherein a complete tree was 'eaten.')
Pros
1. cheap
2. provide a full meal for microbes. Sawdust provides only cellulose. When you add back in the bark, leaves, and some roots, you get a complete nutritional package for a variety of microbes.
3. makes a great mulch to shade and retain water in underlying soil.
4. usually long lasting

Cons
1. large particles can be unsightly
2. large particles can smother turf underneath
3. difficult to spread evenly
4. old wood chips are usually unsightly

[jkelton]

Just thought I would post a couple of before/after pictures of a lawn I did this fall. The landscape contractor aerated the lawn very well and I came in a blew in approx. 1/2" layer of high quality compost injected with seed.

[jkelton]

Before

[jkelton]

After

[timturf]

sand topdressing can create a layer in soil profile, I SEE NO BENEFIT to applying sand to residental lawns, and wuold be careful with applying a thick layer of compost, I would agree with 1 to maybe 2 cubic yard per 1000. NO MORE!!!!!!!!!!!!!!