Re: Any garden chemists out there?
Johnson Cyndi D Civ 95 CG/SCSRT wrote:
I'm hoping for chemistry help. Any of you Master Gardeners want to comment?
I had my vegetable garden soil tested because I've had such a problem with
blossom end rot on my tomatoes, last year probably 90% of the crop had it. I
know the conventional wisdom says this is caused by lack of calcium due to
uneven watering, but my entire garden is on an automatic drip system and I
have a hard time believing that's uneven (although it gets very hot here you
know, so maybe the plants can't take up enough water during heat waves?).
Anyway the results of the test:
Ph is 6.5. CEC is 13.9. ECe is 3.6 with a bar next to it indicating
Organic Matter - 6.2% (high)
Nitrogen ppm - 66 (very high)
Phosphorus Weak Bray ppm - 165 (very high)
Phosphorus NAHC03P ppm - 246 (very high)
Potassium ppm - 655 (high)
Magnesium ppm - 247 (medium - towards the low end of medium)
Calcium ppm - 1776 (medium - lower medium than the magnesium)
Sodium ppm - 147 (very low)
Sulfur ppm - 147 (very high)
Zinc ppm - 29.3 (very high)
I've read the booklet a number of times but a lot of this chemistry isn't
sinking in. Based on what I understand right now, I should grow some heavy
feeding crops to bring down the nitrogen, and while the sodium is low, the
ECe - which I gather is other kinds of salts (huh?) - is high. The booklet
says "consult a specialist" about that. Everything else says "take no
Web sites I found about BER say to avoid "ammoniacal nitrogen". We use a
lot of spoiled hay and sheep manure in the vegetable garden - would that be
a source of ammoniacal nitrogen?
I'm unclear as to the distinction between CEC and ECe, but both are
measures of electrical conductivity, which in turn is a function of
the dissolved salts in soil moisture. All ions, whether Na, K, Ca, Mg,
etc. contribute to the total dissolved solids/salts.
Available Nitrogen in soil is either nitrate (NO3--) or ammoniacal (NH4+).
Your spoiled hay and sheep manure would be sources of NH4+. I have never
sniffed either, but if you get a whiff of ammonia, that's the clue.
Vienna, Virginia USA
38.9 N 77.2 W
USDA Zone 7
Max. 95 F [36 C], Min. 10 F [-12 C]
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