Thread: Nitrates
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Old April 28, 2008   #2
dice
Tomatovillian™
 
Join Date: Jan 2007
Location: PNW
Posts: 4,743
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From a brief scan with Google, it looks like nitrate ppm
is not used when making a nitrogen recommendation.

The reason is that nitrate ppm is only a test of the nitrogen
that is "immediately available" to plants. That does not
necessarily reflect how much nitrogen will be available over
the course of the season, which also depends on how much
ammonium nitrogen there is, how much nitrogen is made
available by conversion of the ammonium nitrogen to nitrates,
how much nitrogen is bound up in organic matter that will
be released by bacteria, fungi, and worms as the season
warms up, and so on.

So all that really tells you is that your nitrate nitrogen is
high enough to get your plants off to a fast start.

I would add only compost to a soil that tested like yours.
Then I would keep an eye on the plants and see if they
show any nitrogen deficiency symptoms on the leaves
( http://4e.plantphys.net/article.php?ch=5&id=289 ; has an
explanation down below in the pictures specifically for
nitrogen deficiency ).

If they do show lower leaves turning yellow, do a test with
some fish emulsion watered in on one plant. If the yellow
leaves immediately start to turn green, they probably all
need some more nitrogen, so scatter some blood meal around
under them and give them all a watering with fish emulsion.

Odds are, though, that your soil has plenty of nitrogen for
tomato plants, and breakdown of compost over the season
will resupply what the tomato plants use up.

(If you do use some fish, you might put out a raccoon trap
with some cat food in it at the same time. Fish attracts
raccoons.)
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