Question
QUESTION: My vegetable garden soil plot is depleted in the nutrients, Nitrogen, Phosphorus and Potassium, yet it is rich in organic matter.

I rent out a vegetable garden plot from a local organic community garden program.  I have had this garden plot for 2 years now.  This past year I added leaves and straw (mulch for plants) to the garden to improve the quality of the soil.  Finally in December I  decided to have the soil tested at a university laboratory.  

According to the results:

The soil has below optimum levels of Phosphorus ( 34 parts per million ), and Potassium ( 159 parts per million ).  I also have above optimum levels of Magnesium, at 708 parts per million.  My calcium level is 9126 parts per million.   The report said the soil ph is 7.7, a ph of 6.0 to 7.5 is fine for most plants.  I should avoid acid loving plants.  My target ph for the soil according to the report is 5.3

I took scattered samples of soil around my plot, at a depth of approx. 6 inches, I did this in December.  A couple of months prior to this, I put a whole bunch of leaves on my garden plot to help enrich the soil, and I also used straw as a mulch the last two summers.

Here is the info. about the soil:

This soil is a sand or loamy sand.  It has low nutrient and moisture holding capacity, and will benefit from the addition of large quantities of organic matter, such as manure or compost.  Work in organic matter to a depth of 8 inches, before planting, and use a mulch around established plants.  Organic matter must be continually replaced.  Soluble nutrients, especially nitrogen, will leach through this soil rapidly, contributing to ground water contamination.

Your soil is 43.9% organic matter.

The MSU Soil and Plant Nutrient Laboratory recommends that you apply:

3 lbs of nitrogen per 1000 square feet
2.9 lbs of phosphate per 1000 square feet
1.2 lbs of potassium (potash) per 1000 square feet

In Spring before planting work 8.3 lbs / 1000 square feet of 12-12-12 along with 4 lbs / 1000 square feet of 0-46-0

Work these fertilizers into the top 4 to 6 inches of soil.  Six weeks after planting or six weeks after plants emerge use 12-0-0 applying 8.3 lbs / 1000 square feet.  Apply between plants ( do not get it on plants and keep it back away from stems).  Water it into the soil well.

I was surprised to learn how depleted the soil was, because the soil looks so rich and dark and feels moist.  But the soil is rich in organic matter, 49.3% according to the report.

My tomato plants were not very productive, though did bear some nice fruit.  The same kind of tomato plants did much better for friends of mine.  My onions were not very large.  The cabbage family plants were ok, but susceptible to the black flea beetle.  Basil, swiss chard, cilantro, parsley, and cucumbers all did fairly well.

Lots of horse farms around my area.  Should I apply fresh horse manure to the frozen ground now in late January so that buy the time the soil gets plowed in May it will have the nutrients needed ?

ANSWER: A+ work, sir.  What a pleasure to read your report and the sage, intelligent steps you have taken.  Let's go over it point by point.

For two years, you have been growing Herbs, maybe Broccoli or Brussels Sprouts (Cabbages), Tomatoes, Onions, Cucumbers.

For the record, Cabbages are a nonstop party when it comes to Aphids and Cabbage Moth larvae.  But if you are having Black Flea Beetle problems, you're probably growing stuff like Rutabega, Turnips, Chinese Cabbage or Mustard.  These are a cinch to protect against with simple Row Covers, Yellow Sticky Traps (which you can make) and/or Parasitic Nematodes; Ground Beetles, certain Birds, and Toads love to snack on them; Coffee Grounds, Mint and Garlic, among other things, repel them very effectively.  Be diligent about Crop Rotation (I have a feeling that you are very good with that) to intercept succeeding generations of this insect -- and by the way you can expect last year's larvae to be getting ready for another Bumper Crop of these insects in early Spring, so be prepared.

But you asked about your Soil.

You did not mention tilling in your Mulch, nevertheless somehow the Sample from 6 inches down reflected a 44 percent reading in Organic Matter -- nice work.  You must be doing something right.  Let's understand why this did not translate into a perfectly wonderful Soil profile.  (And this is WHY we TEST Soil -- it's full of surprises.  You definitely got your money's worth.)

I have to assume you are being thorough about your description of your Mulch, which you say is 'Leaves and Straw'.  You did not add Compost.  Or Manure.  Or Humus.  

You added no Bone Meal, no Bloodmeal or Cottonseed Meal.  Just lots of Leaves and Straw.

Bear in mind that it's the decomposed product of these ingredients that improves Soil -- and Brown Leaves and Straw are primarily Carbon-rich.  Nitrogen is a fleeting, instable molecule that vanishes with the loss of Chlorophyll.  As your Leaves decompose into that highly prized pre-Humus amendment called Leaf Mould, they suck Nitrogen from the Soil as fuel for the Bacteria and Fungi doing all the work; the process slows down according to how quickly they run out of N, or how much raw concentrated Fertilizer or other chemicals you apply that damages the microbes population.  Next thing you know, they're running on empty.  So rotting organic matter is only half-done.  Unfinished business.

In Phosphorus-rich Soil, the P is frequently present but NOT AVAILABLE to your Crops because it's LOCKED UP with Iron in the Soil (see why casually adding Iron to your Soil is such a bad idea?  But people do it all the time).  Here, you have a different problem.  You actually have a deficiency of P.

Bone Meal is a nice, healthy way to rebuild P levels.  To serve it to your plants, mix it into the Soil around the root zone.  You can count on the Humic Acids that are developing from rotting Leaf and Straw Mould, Earthworms and microbes; they turn P into reactive Phosphate Rock or Superphosphate that your Crops can use.

As for your low-Potassium predicament, I have a warning for you: Under no circumstances should you EVER add Potassium Chloride to boost your K.  That stuff will kill every Earthworm down there; there goes your Humic Acids.   It's also called Muriate of Potash.  Use Greensand or Wood Ashes instead.

I don't want to drag this out too much longer, but let's discuss Manure for a minute, since you asked about it.  Oregon State University says Manure is distinguished for its high readings for SOLUBLE Nitrogen, Ammonia and/or Salt -- as well as a high pH (above 8) reading:

慍omposting transforms soluble Nitrogen in Manure to slow release organic forms, decreases Ammonia to levels that do not injure plants, and sometimes reduces pH (to 7 to 7.5). ... It is best to avoid Manure and Manure-Composts for high-rate application.?br>
Your Alkaline Soil needs another elevated pH amendment like a hole in the head.  But incorporating it with a LOT more Leaves, and some decent Compost, will be good for it.  The Alkaline Soil under cultivation gradually becomes more Acidic -- lower pH is a natural effect of farming because growing Vegetable plants remove Basic Minerals from the Soil (Calcium, Magnesium, Potassium) as they grow.  Generous P levels are needed for Fruits and Vegetables.  To quote your own Soil Test on Soluble N, 'Soluble nutrients, especially Nitrogen, will leach through this Soil rapidly...'

Still with me?

One critical nutrient you can expect to run out of:  Iron (Fe).  Add all the Iron Supplements you want, but if you don抰 correct the pH, that Iron will never get into the roots.  Fe is locked up and inaccessible to roots in Soil with a high pH.

Most important:  Start a Compost Pile.  With the right technique and a few accessories, you can accelerate production right there in your Vegetable Garden.  But you MUST pay attention to the C:N ratios.  As they explain so well on the Organic Gardening website, 慣he ideal ratio of Carbon to Nitrogen in a Compost Pile is about 30:1.  A pile with that balance of materials will rot steadily, and it will yield nutrient-rich Compost.? Here's the url:

http://www.organicgardening.com/feature/0,7518,s1-3-79-112,00.html

I urge you also to review -- carefully -- their C:N schedule, posted here:

http://www.organicgardening.com/feature/0,7518,s1-3-79-112,00.html

You抣l see readings like Wheat or Oat Straw, 48:0.5 (that抯 ZERO POINT FIVE, not FIVE!).  Fresh Cow Manure, apx. 12-20:0.6-1.0.  Fallen Leaves, 20-35:0.4-1.0.  You want to add a lot of Green, Red and Orange things, maybe the leftover Orange Juice from morning breakfast, the Eggshells from your scrambled Eggs, any expired Apple or Pineapple Juice, Lemon rinds, scrapings from the dinner Carrots, your neighbor's Lawn clippings, etc.  Then there's Fish Emulsion, Bloodmeal, and all the other goodies you've heard of. Superlative Soil is your goal.  Don't try to short-cut the results with bottled concentrated Fertilizers; one step forward, two steps back will be the result.

Finally, my friend, remember that old Gardener's saying: Rome was not built in a day.  It takes time to get a PhD, build muscles, gain weight, grow old, alter pH or reboot your Soil.  Sandy Soil does not transform into one that is nutrient 'rich' overnight.  It takes time, because microbes take time.  If you eat a lot, it takes time to get fat.  If you diet, it takes time to get thin.  Soil takes time to develop, too.  All good things come to those who wait.

Hope this was worth waiting for.  I try not to talk too much, but I don't see any way to compress this information any more than I have already.  Your followups welcome.  Thanks for your question.

---------- FOLLOW-UP ----------

QUESTION: My follow up questions are the following:

I took the soil sample that was used for the lab results back in December when the ground was cold, but not frozen through.  Does this cold temperature effect the result?  For example I noticed at the bottom of the lab report that it states that samples taken from January to June will yield lab tests of lowered Potassium by 1/3.  

The horse manure that I was interested in contains some pine shavings which I presume adds more carbon to the mixture.  This carbon in theory ties up the nitrogen when the bacteria try to decompose it.  You still think it would be better to compost the horse manure in the kind of complex compost system you describe to give me the kind of superlative compost rich in the correct ratio of carbon to nitrogen as well as other organic benefits?

What do you think of using a field pea ( possibly in combination with oats )  cover crop ?  I could plant these seeds in March sometime when the soil warms up enough.  The garden plot that I rent out will automatically be plowed in mid May by a big kind of machine.  It gets plowed at the end of October or ealy November as well.  I realize that I have to add an inoculant of bacteria to the field pea seeds in order for them to be able to fix nitrogen into the soil.

Finally, I do grow mustards, kale, cabbage, and black radish. Do you think coffee grounds as a mulch around the plants should repel the black fea beetles ?  The garlic should be ground in some water and the resultant slurry should be applied to leaves to repel the beetle ?  I do realize you mentioned the row covers.

Answer
In editing the answer I posted earlier, I did delete quite a bit of material about the pro's and con's of taking Soil Samples in cold weather.  In the cold temps like we have now, there is NOTHING going on down there.  I am surprised they did not delay your test. University of Georgia College of Agricultural and Environmental Sciences advises gardeners:

慡oil Samples can be taken any time during the year; however, Fall is the most desirable time... Soil pH and nutrient levels will be at or near their lowest points during late Summer and early Fall.?br>
Clemson University Coop Ext Service also warns against seasonal variations in Soil testing:

http://hubcap.clemson.edu/~blpprt/pdf/acidity2.pdf

Researchers Joseph Keogh and Richard Maples did a study.  Which you can read in full at the link above.  Generally, they observed 憀ower pH values in the Spring and Summer and higher pH values in the Fall.? Your Soil Testers say your Potassium readings will also change.  Fall samples are probalby more accurate than samples in late Winter or early Spring, but since you抮e growing your Vegetables in the Summer, Summer data would be most accurate.

It is nice though to get this over with.

It would not be unreasonable to figure that the pH you were quoted is probably comfortable, if slightly elevated, when you put shovel to Soil in the growing season.  Also consider that Soil N levels fluctuate A LOT, plus this is a complicated subject anyway, so the N reading is not all that helpful.  So yes, the cold temps matter.  And you can keep that in mind when you review the paperwork.

About that Manure you mentioned... I did not mean to make it complicated, and I apologize for that.  This should be kept as simple as possible.  There's just too much to worry about not to make it simple where we can.  And it boils down to this:  'Green' (Nitrogen) and 'Brown' (Carbon) Compost in a ratio of 1:30 (N:C) is the ideal mix because it caters to the metabolism of the decomposers.  Cook it in the Composter, turn regularly, keep moist, etc -- you know how to do that?  If not just ask.  It would be nice to have access to a lot of organic mowed Lawn Grass for this.

Adding Wood to Manure creates possibly a perfect growing medium for Mushrooms.  A bit too Sunny I would guess, but perhaps not.  Something tells me this is not part of your plan...

Bacteria involved in the decomposition process consume a lot of Nitrogen; the immediate result is a Nitrogen deficiency for anything growing in the area.  That's why we Compost first.  A Compost pile that is Carefully composed and tended accelerates the results.  Manure is NITROGEN (Green) in the N:C ratio; you can see you need an awful lot of CARBON to come up with a 1:30 ratio or even 1:25.  You'll know things are going wrong if you have an Ammonia odor from the pile; that means you NEED MORE CARBON (i.e., Wood Chips, Brown Leaves).

I don't think I've mentioned something about Coffee (Green) that I should have.  Which is, I have learned that Coffee tends to FLAVOR at least some of the produce that you're growing.  At least, it flavored my Strawberries and my Tomatoes.  Not unpleasantly, but it altered the Berrieness of the Strawberries, which should be considered a capital crime as they are so delicious when you don't ruin them as I did.

I am very big on Cover Crops.  Send a separate question that as it is quite involved.  Short answer though is go for it.  There are many.  It doesn't get easier than a Cover Crop, just plant and grow and the stuff works on your Soil for you.

There are several ways to use Garlic, among other things, as a weapon.  I see the National Sustainable Agriculture Information Service has a fairly clear page on this matter:

http://attra.ncat.org/attra-pub/fleabeetle.html

Golden Harvest Organics website maintains that simply pureeing Tomato leaves in water uses the alkaloids in the leaves and repels harmful insects:

http://www.ghorganics.com/page14.html#Tomato%20or%20Potato%20Leaf%20Spray

and Cahri's Bugs Online has their own system of dealing w/ Flea Beetles:

http://organicgardensite.com/?p=35

Not complicated -- but if you know what you're doing, you can do it faster and better.

Your further followups are most welcome, but if this gets too long the question crashes... so better to type a new question in.