Tuesday, May 23, 2006

Organic gardening fertilizer applications

Fertilizing frequency is an important topic for several reasons. Issues such as
cost, toxicity to plants and/or humans, and seepage into ground water sources
are a few.

I'll answer your questions first, and then explain in detail the reasons for
them. Yes - if you want to continue to produce a crop throughout the growing
season. and yes, the fertilizer slowly feeds the plants.

How many times to feed should only be an issue with ever-bearing crops, such as
squash, tomatoes, peppers, cucumbers, etc., because single crop varieties, such
as cabbage, lettuce, and spinach only receive between 3 and 5 feedings after
transplanting, and you stop feeding 3 weeks before harvest.

Does everyone remember the comparison I have made with organic growers, who
apply 2-3" of manure on their garden before planting? Let's review that quickly
and make the comparison with the Mittleider Method, to put the toxicity and
ground water polution issues into perspective (and hopefully to discourage you
from indiscriminate applications of manure).

Some folks laud manure because it's only 1% nitrogen, and curse ammonium nitrate
because it's 34%. However, they may not have checked their math on what is
actually happening. Applying just 2" of manure to a single soil-bed (not the
aisles - just the growing area) adds 250-300# of manure to the soil. It also
adds about 2.5 pounds of nitrogen. That's a lot of nitrogen all at once - the
equivalent of over 7 pounds of 34-0-0 - and will often burn young plants or
emerging seedlings.

The Mittleider Method advocates applying 1# of Weekly Feed mix each week to that
soil-bed. The WF mix is 13-8-13, therefore you have added 2 ounces of actual
nitrogen to your soil. For you to apply as much nitrogen as the organic
gardener you would have to apply the WF 20 times! In addition, they apply it
all at once, and much is therefore susceptible of being toxic to your plants
and/or washed into the ground water system. You, on the other hand, never have
more than a couple of ounces at a time in the 3,000+ pounds of soil that make up
the top one foot of your soil-bed.

Your plants need water-soluble mineral nutrients constantly throughout their
growing cycle, but nitrogen is volatile and returns to the air. Also,
phosphorus and potassium become fixed (adhered) to the soil particles fairly
quickly, and so become unavailable also. Therefore, we feed weekly to overcome
those problems - rather than applying everything all at once at the beginning.

Some people are tired of their garden and fresh produce by the first of August.
If you want to continue producing right up til winter frost kills your plants,
you should keep feedingthem until a few weeks before frost. We recommend 8
weeks for tomatoes, 6 weeks for peppers, and 4 weeks for cucumbers.

Jim Kennard

----- I have a question about the
frequency of fertilizing my plants. Say, for example, my summer squash is to be
done 5 times in the growing season (that is if I remember it correctly from the
chart in the Food For Everyone website). We have a long growing season. I start
my squash in February and am still picking squash in late June and July. Do I
need to keep fertilizing for a longer period of time? I also have some Swiss
Chard I planted in September, and it is just beginning to bolt now in May. I fed
it off and on throughout the winter. I'm just wondering how the fertilizer works
in the soil. Does it slowly feed the plants?


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