Question
Hello,

I have been in my new construction home (where they scraped off the top soil and left clay) near St. Louis Missouri for the last 4 years.  I have struggled to get anything to grow.  Even the some weeds seem to have a hard time.  I am planning to start from scratch.  I plan to get a soil test, till up the yard with amendments as needed, and apply seed in the fall.  I saw in a recent post that you recommended a clover crop.  Would this be a good idea in my situation?  Could you explain this in more detail?  I wouldn't mind a yard of clover for a while, but would it spread to my neighbors yards that chose to sod rather than seed?  Any suggestions would help because I have tried the chems and they have not helped.

Answer
You're worried that planting Clover will contaminate your neighbors' Lawns?  Clover used to be the hallmark of the Luxury Lawn back in the 1950s, before Scotts gave Clover a bad name by listing it as a 'Weed'.

And why did that matter to Scotts?  Because their broad spectrum Weedkillers killed Clover along with Dandelions, Creeping Charlie, Crabgrass and every other invader.

Clover is great.  Don't let anybody tell you otherwise.  This is not genetically modified Corn you're thinking of growing.  It's a Nitrogen fixing, Earth-loving, ultra-Green gem.  It's the 'plus' in ne plus ultra.

Let's talk about your Clay.

It's GREAT!

I LOVE Clay.  So do you.

Yes, you hear people complain all the time about Clay.  It's hard to dig.  It's slippery when wet.  Amended with the wrong stuff, it's a nightmare.

Some people figure they'll 'lighten' their Clay by taking buckets of Sand and mixing it to death.  So amended, Clay Soil turns into instant hardpan as hard as solid rock.

However, Clay is PACKED with Vitamins and Minerals.

Reason:  Its Aluminosilicates (Al4Si4O10(OH)8) base.

Those Aluminosilicates are NEGATIVELY charged.  That gives them the power to hold POSITIVELY charged ions.  The kind you find in Calcium (Ca2+). Magnesum (Mg2+). Potassium (K+).  Ammonium (NH4+).

Scientists actually rate Soil by its ability to hold positively charged ions.  That's exactly what the Cation Exchange Capacity is -- the 'CEC'.  The more Clay in your soil, the BETTER the CEC.

Soil with a HIGH CEC rating HOLDS MORE NUTRIENTS because Calcium, Magnesum, Potassium, and other plant nutrients stick to them like glue.  This is the ONLY way to grow ANYTHING green in a garden.

But everything is relative.  So let's take a quick look at Sandy Soil.  Sandy Soil may drain wonderfully, and that's a very good talent.  But Sandy Soil is the BIGGEST LOSER when it comes to Cation Exchange Capacity.  It CAN'T hold nutrients.  ZIPPO.  NOTHING sticks to Sand.  Fertilizer in Sandy Soil just flows right through it, like it was never there.  So you don't get much of a Lawn when you grow it in Sandy Soil.

Think of Clay Soil as a Copper Pot.  Think of Sandy Soil as a Vegetable Drainer.  Which one do you think is going to hold the water around the roots long enough for them to absorb it?

Now, all Clay is not alike.  There is Montmorillonitic Clay -- [(1/2Ca,Na)0.7(Al,Mg,Fe)4(Si,Al)8O20(OH)47nH20] (aka 'Smectite' Clay, and it has a very impressive high CEC).  Illitic Clay -- [K1-1.5Al4(Si7-6.5Al1-1.5O20)(OH)4].  Chloritic Clay -- [(Mg,Al,Fe)12(Si,Al) 8O20(OH)16].  if you lived in the Southeast, 'Clay' would mean Kaolinite, the aforementioned [Al4Si4O10(OH)8] -- actually the lowest CEC of the Clays.  In other regions, it could mean Vermiculite -- [(Mg,Ca,K,Fe11)3(Si,AL,Fe111)4O10(OH)2O4H2O] (with the highest CEC).  Soil with a high CEC resists fluctuations in pH.

By this time, you should be dizzy from Chemical Formulas.  But I want to make one other point while we're on the subject: There is a 'pecking order' for these Vitamins and Minerals, all based on how strong the charge and how big the molecule.  At the top is Aluminum.  At the bottom is Sodium.  In between (in order) are Calcium, Magnesium, Ammonium, and Potassium.  Why should you care about this?  Well, if you feed your Grass too much Calcium, there will be no space left for Magnesium or Potassium.

Clay is good for other reasons.  It binds Soil particles together, and it holds moisture in ways Sandy Soil can only dream of.  Peat Moss, Humus and Compost, even AGED manure added in a ratio of 1:1 to your heavy, thick Clay would create your PERFECT Soil.  You can read up on this in the Potash & Phosphate Institute's cheat sheet on the subject, 'Where Do Cations Fit in My Fertility Program?':

www.ppi-ppic.org/ppiweb/ppinews.nsf/73B193CB2CE9DFF285257173004C875E/$file/Cation+Behavior.pdf

Let's look at the Magic Ingredient, HUMUS.

Humus also has a very strong CEC.  It's made of a combination of (mostly) Carbon, Oxygen and Hydrogen, and carries a net charge that's Negative.  So it's similar to Clay in some important respects.  But of course, you can't shape Humus into Teacups and fire it to make waterproof Cups and Saucers.

By the way, chemical fertilizers are almost always TWO Elements or Polyatomic Ions bonded to create a Salt.

University of Vermont Extension Service points out the value of Organic Matter for improving Clay: 'Organic matter is a great improver for both Clay and Sandy soils.  Compost, Manures, leaf mold, sawdust and organic amendments improve Soil structure and thereby increase its water-holding capacity, aeration and Water infiltration.  These materials are decomposed in the Soil by Soil organisms and their byproducts release plant nutrients and provide sites for nutrient retention.  ... Adequate Water must be present, and warm temperatures will increase the rate at which the microbes work...'

The full report is posted here:

www.ext.vt.edu/pubs/envirohort/426-313/426-313.html

Now, if you're looking for inspiration, you ought to have a look at this illustration in Mother Earth News and the caption:

www.motherearthnews.com/Organic-Gardening/1986-09-01/Green-Manure-Crops.aspx

It says: 'After only two years of green manure cropping, Ecology Action's gardens were transformed from barren ground to the verdancy shown here.'

More advice: 'To get the maximum benefit from a green manure crop, you should compost it. If, instead, you spade or till it directly into the soil, you'll have to wait 30 days for it to decompose before you can plant again. (Turning under such a crop is also quite arduous.)'

They list their favorite Green Manure Cover Crops: Cereal Rye ('produces lots of organic matter'), Mustard ('very fast'), Alfalfa ('better used for long-term soil buildup . . . say, in an area you plan to start cultivating in a year or two') and Banner Fava Beans ('If your Winters don't drop below 10 degrees F, a Fall planting will keep growing throughout the cold months.').

Next 4 favorites: Alsike Clover ('tolerates depleted, acidic, and poorly drained ground . . . [and] produces an adequate (not large) amount of Green matter and Nitrogen).'

Fodder Fadish ('deep taproot ... produces more organic matter per day than almost any other green Manure crop.'

Woolly Pod Vetch ('like Alsike Clover, good at growing in poor Soil .. medium-fast-growing ... ').

Foul Muddammas Beans ('fix up to 16 or more pounds of Nitrogen per 100 square feet').

There are LOTS of cover crops you can choose from.  My favorite is still Alfalfa.  Before you do your Soil test, work on the Soil Organic Matter numbers with your Cover Crop.  And when you do till, make sure to do it LIGHTLY/ROUGHLY, so that you don't scare the Earthworms away.  Your followups invited.

THE LONG ISLAND GARDENER