# Boosting Organic Matter In Soil



## daviddsims (Apr 15, 2018)

I have a two year old centipede lawn that my soil test says is very low in organic matter. I'm currently mulching the grass at about two inches and used some Milorganite in the spring. Is there anything else that I can add to help the soil become better quality than the builder grade red dirt?


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## ATLawn (May 25, 2017)

Boosting your soil's OM is a years long process (especially when starting out in the 1-3% range), and there are no short cuts. recycling clippings and using organic fert is a good start, but I've come to learn, as a novice myself, that that's not enough to see any significant change any time soon. Really the only foolproof way to boost OM relatively quickly is by dumping heaps and heaps of organic materials on the lawn. Compost, peat moss, shredding your fall leaves (and your neighbors fall leaves), saw dust (although be careful here. You can create serious N deficiencies for your turf by piling on saw dust), used coffee grounds, etc. Lots of hard work and as often as your lawn, body, and wallet can handle. Don't fantasize and obsess over OM, as it's not the end all be all. Play the long game and do what you can, when you can, and you'll see gradual improvements year after year.


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## Ware (Jan 28, 2017)

ATLawn said:


> ...Don't fantasize and obsess over OM, as it's not the end all be all...


+1


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## Greendoc (Mar 24, 2018)

If I wanted to add good OM to soil without creating problems, I would look into the sprayable or spreadable humic formulations. Incompletely decomposed OM(compost) is not the most desirable thing to put on a lawn. Sure, you get a little bit of short term greening from the 0.5-1% N in the compost, but you now have something that will shrink and settle unevenly, making it hard to mow when that happens. It is also not guaranteed that what is put on the surface as undecomposed material even gets into the soil and subsoil where it is needed. Compost can simply add to the thatch layer.


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## Tellycoleman (May 10, 2017)

I wonder how much OM is in a 6 inch layer of sand at a local golf course putting green?
Still great grass.


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## Ware (Jan 28, 2017)

Tellycoleman said:


> I wonder how much OM is in a 6 inch layer of sand at a local golf course putting green?
> Still great grass.


 :thumbup:


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## Greendoc (Mar 24, 2018)

25-30% added as steam sterilized or gas fumigated peat moss. Growing grass adds so much OM to the sand that a necessary practice is to core aerate and remove cores before filling the holes with straight sand. I have been told by PhD level agronomists not to add OM, just grow the darn grass by supplying whatever NPK+micronutrients needed.


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## Ridgerunner (May 16, 2017)

Ware said:


> ATLawn said:
> 
> 
> > ...Don't fantasize and obsess over OM, as it's not the end all be all...
> ...


+1
The most efficient, effective and easiest method for raising OM is to grow your own: roots. Based on annual root slough off (33-50% of 315 grams of total dry root mass/ sq yd.); should add between 26 and 38 lbs/M of dry organic material per year. Slow, but steady, and requires no additional effort or expense.

Fresh organic material can take 10 years to become Organic Matter (OM).
1% OM is approximately 460 lbs/M.
Theoretically, discounting any loss of carbon by way of CO2 production etc., that would require the application of 568 lbs/M of some dry fresh organic material like dried out leaves.
If your objective is to raise the nutrient holding capacity of soil (CEC) and if my math is correct  :
1% OM is estimated to have a CEC of about 2 meq.
Adding 220 (edited) lbs/M of peat moss should increase CEC by about 1 meq @ 4".
Adding 12.3 lbs/M of humate (dry humic acid or 12.3 gallons/M of a 12% humic acid solution) should increase CEC by about .19 meq @ 4". It would require 64.7 gallons/M of a 12% humic acid solution to raise CEC by about 1 meq @ 4". Applying 9 ounces of a 12% humic acid solution per 1000 sq feet would add about 0.0133 meq to soil CEC @ 4".


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## viva_oldtrafford (Apr 4, 2018)

Tellycoleman said:


> I wonder how much OM is in a 6 inch layer of sand at a local golf course putting green?
> Still great grass.


A usga spec green (few specs you can choose from) has a 12" layer of sand and is built at an 80/20 blend. 80% sand and 20% (by volume) OM. Research shows that soils with excess of 3% om by weight, can have negative impacts on plant growth. OM is negatively charged, so it holds water (water is polar) - with an excess amount of OM stored in the upper profile, roots have no need to venture to greater depths in search of water - it also leads to soft/spongy conditions (may not matter much to a homeowner). When we aerify, we use a pure sand topdressing because OM is the devil and our sward provides enough over time.


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## Greendoc (Mar 24, 2018)

Right there. This explains why I see grass put down deep roots in sand and stay at the surface when growing in an OM/clay mix commonly sold as "lawn and garden topsoil". If people have sand, I have told them not to bring anything in. Grow the grass on sand. Grass makes its own OM just fine.


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## MasterMech (Sep 24, 2017)

Tellycoleman said:


> I wonder how much OM is in a 6 inch layer of sand at a local golf course putting green?
> Still great grass.


Just keep in mind that awesome grass also demands a LOT more inputs than even a high-end home lawn. There's a lot more to it than just planting in sand and setting the mower at .120". I used to help maintain old, "push-up" greens. (Native soil "pushed up" to form the green.) They had their challenges, and certainly more frustrating to water and move the cup than a USGA spec green. But we could still keep them rolling a 10 or better consistently.


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