The Litmus Test - Soil Testing

Do you test your soil?  They say you really should if you are going to start adding particular elements to it and not just organic matter (compost).  Why would you add Potash if you already had an excess?  Exactly HOW much Nitrogen should you be adding?

There are many universities which offer soil testing through their extension offices.  But to be honest, the sample prep instructions can be a little intimidating.  So just how good are the over the counter tests?  Accuracy varies by technique of course.  I have a scientific mind (according to NY State standardized testing and Facebook quizzes) so I decided to give the tests a try.  I did watch a bunch of Youtube videos to gather info and to learn from other's mistakes.  What did we do before Youtube? 

I took a half cup sample from the center of each bed, from the layer that lies about 4 inches deep,  placed them in labeled quart jar and mixed it 1 to 5 (2.5 cups) with distilled water.  Then I shook the sample well to "dissolve" it in the water, and let each sample sit for almost 24 hours.

The Luster Leaf 1601, which I purchased on Amazon, contains four test vials, and ten capsules for each type of test.  You can test four attributes of ten samples.  You pull apart the teeny tiny capsules and empty them into the left side of each vial.  Then, you use the supplied eye-dropper to add your sample water.  Shake the test well and let it sit for a couple of minutes.  Then you have to interpret the subtle shading by comparing it to the colored scale provided.  The Acid test and the Potash test registered pretty clear results.  The Acid was actually easier to read in real life than it shows in the photos below.  The Phosphrous and Nitrogen were more subtle, but did vary from bed to bed.

Each of my twelve raised beds have had the same components added to them over the years.  The same starter soil.  The same compost in comparable amounts.  Similar soil additives each year.  But they have different crops grown in them each year.  If I am growing tomatoes or cucumbers I am more likely to add nitrogen.  If I am growing peas or a cover crop I am not adding anything that season.  And they have developed differences over the years.  This is apparent in my annual growing results. 

Here are the results for my seven samples.  I did test the cauliflower bed a few weeks ago before I planted them, but I did not take a photo.  Results were PH Neutral, Adequate for Phosphorous, Depleted for Nitrogen and Adequate for Potash.  I think these photos will be useful for future reference.

Bed #1
Acidic, Sufficient for Phosphorous, Depleted for Nitrogen, Adequate for Potash
This bed had a cover crop of buckwheat last year

Bed #2
Slightly Acidic, Depleted for Phosphorous, Adequate(ish) for Nitrogen, Sufficient for Potash
This bed had a cover crop of buckwheat last year 

Beds 3 and 4 have peas planted in them.  Peas grow well in "poor" soil, 

so I did not test this year

Bed #5
Slightly Acidic, Depleted for Phosphorous, Adequateish for Nitrogen, Sufficient+ for Potash
This bed had a cover crop of buckwheat last year

Bed #6
Slightly Acidic, Depleted for Phosphorous, Adequate for Nitrogen, Sufficient for Potash
This bed had a cover crop of buckwheat last year

Bed #7
PH Nuetral, Adequate for Phosphorous, Adequate for Nitrogen, Sufficient for Potash
This bed had cucumbers in it last year

Bed #8
Slightly Acidic, Depleted for Phosphorous, Adequate for Nitrogen, Sufficient+ for Potash
This bed had cucumbers in it last year

Potato Bed
PH Neutral, Adequate for Phosphorous, Adequate for Nitrogen, Adequate for Potash
I expected this bed to be more acidic judging from the amount of moss it grows.

So what do the results above tell me?  My soil, overall, is more acidic than I thought it was.  That doesn't really concern me at this point, but I'll keep an eye on it and perhaps add some garden lime to my composted horse manure as I amend the beds.  I have lime on hand already.   The Nitrogen could use a little boost, but I habitually do that by adding blood meal at the time of planting.  The Phosphorous needs attention.  I have not concentrated on adding that in the past.  How do you add Phosphorous to your soil?  Bat Guano, Bone Meal or Rock Phosphate.  I will probably go with the Bone Meal which has a 4-12-0 N-P-K ratio.  N (Nitrogen) P (Phosphorous) K (Potassium) 

I think the over the counter soil tests worked fine.  The results weren't really surprising.  I will continue to do what I have been doing, but this year I will buy a good sized bag of Bone Meal (P) to add as I plant along with the Blood Meal (N).