Results of the soil testing

Great Maiden's Blush (Alba, circa 1400)
Great Maiden’s Blush (Alba, circa 1400)

I received the report from the NC Dept of Ag Soil Testing Service and the results were not as bad as they could be.   Most of the nutrients are in good supply.  Potassium is in the good range and Phosphorus is almost off the chart (but because of the pH, it isn’t really available to the plants).  The issues are:

pH is too low

What a surprise! (not)  First of all, the soil around here tends to be on the acidic side and when you consider that I have dumped pine bark mulch on the beds for years, it is no wonder that the pH is low.  Some beds are worse than others but the report does give a recommendation on how much lime to add to bring the soil pH up to the desired range. This is the big reason to get the test… so you know how much lime to add. The unfortunate thing is that adding lime to the soil is not instantaneous; it works slowly and doesn’t “move” in the soil, which means that you have to mix it into the soil for it to have good effect.  So, if I apply it today, it may be fall or even next year before the pH level actually rises.  Still, you have to start someplace.

Needs nitrogen

The other recommendation is to add Nitrogen.  The testing does not actually test for nitrogen because it moves quickly through the soil and varies so much.  With the good levels in phosphorus and potassium, the 2nd and 3rd numbers you see boldly displayed on bags for fertilizer, the recommendation is for using 21-0-0.    I checked and they don’t appear to sell fertilizer that is just nitrogen, which doesn’t really surprise me. I think the primary fertilizer that commercial farmers use in this case is ammonium nitrate, which they buy in bulk.  In addition to being fertilizer, is a primary component in ANFO (ammonium nitrate/fuel oil) explosives.  So I am not really surprised that such stuff is not directly available at someplace like Lowes (though it might be available in home gardener quantities at someplace like Southern States or Family Home and Garden).  I will have to go with something like 28-0-4.

Still, looking at the report, the recommended amount is in the order of 5 lb per 1000 square feet, which is about 2.25 grams per square foot.  Ok, that’s basically nothing!   Sounds like I would be better off spreading some organic material like well composted manure (0.5-0.5-0.5) or cottonseed meal (5-2-1).

Other Test results

There are additional test results that I still need to look at.  Some are decipherable, like MN-I (Magnesium), Zn-I (Zinc), Cu-I (Copper), and S-I (Sulphur).  Those are expressed as indexes where a value of 50 are optimum.  Of those nutrients, all have high (like over 100) except Sulphur.  However, Sulphur is like Nitrogen in that it is highly variable and moves quickly through the soil.  My basic take on these values is “Get the pH into the right range then look at the values again.”  Other test results like “HM%” and “W/V”  are not as understandable so I need to spend some time reading about what they mean.

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