Organic vs Chemical
Bob Gerardy
sent me in regards to my earlier post on
this thread about removal of bio mass from
a food garden. I decided to post it here as
well.
Let me say that I am NOT advocating the use of synthetic fertilizers and
pesticides. I am mostly organic. I was just trying to make the point that
a vegetable garden is not a closed system.
>I think you've reached a ridiculous extreme with your concern,
>expecially when you consider that the human body is mostly water.
Now, Julie, lets not start flinging in loaded words, it just makes rational
discussion difficult :-). I'm not concerned, just trying to make a point. The
plants we are all wanting to grow are also mostly water. It is the non-water
part that is the main point of discussion. My point is that when you remove
parts of the plants for food, you are removing something that is not
returned. We remove at least K, P and S in significant amounts when we
take plants for food. These must eventually be replaced somehow or
the soil will become depleted.
>Certainly the minerals our carcasses would add would be minimal. The
Not entirely true. Our bodies contain a great deal of P, Ca, Fe, etc.
>bio mass taken from the garden and composted adds these elements back
>to the soil.
Taking bio mass from the garden and composting it ADDs nothing. It does
return what was taken out to grow the plants, often in a form that is more
useful to other plants.
>Some plants can be grown just to get certain elements.
>Buckwheat contains an unusually high concentration of phosphorous.
Except for N, C, H and O, we don't grow plants to GET the elements.
We may grow them to make the existing elements more available. The
buckwheat does not manufacture the phosphorous. No non-nuclear
process can do that. It extracts it from the soil, and returns it when
properly composted, perhaps in a more available form. (By the way,
it is more available partly because it is more soluble, I think.) The
point I wanted to make is that when the P has been made available
by the buckwheat, and then ends up in a tomato, which I eat, it is now
gone.
Thomas pointed out in a later item on the thread that we can add rock
phosphate to help replace the P removed, rather than some soluble
form, and I concur with that approach. My only point is that the garden
is not SELF sustained, if we are adding outside material from any
source, no matter how acceptable.
Someone, it may have been Thomas again, also brought up the
example of a forest, which keeps growing big trees, etc. That is
quite in line with my point. Animals eat the plants, other animals
eat animals, all within the forest, but eventually the animals die and
their remains are returned to the soil. That is not the case with a food
garden. The forest is a closed system (mostly), the garden is not.
Even that is somewhat naive. Rain washes minerals from the mountains
down to the forest, and carries away some soluble material, so even
the forest is not entirely closed.
>
>For info on biointensive method, read the "bible" - "How to Grow More
>Vegetables**than you ever though possible on less land than you can
>imagine" by John Jeavons (Ten Speed Press). Bill Mollison is the
>authority on permaculture. His giant book is called "Permaculture: A
>Practical Guide for a Sustainable Future" (not sure of publisher -
>borrowed it, don't own it). Masanobu Fukuoka's book is "The One-Straw
>Revolution" (Rodale Press). Good luck.
Thanks! This is what I really wanted in response.
Sorry if I got a little long winded.
Bob
>
>Julie
>
Thomas C. Waters
rob...@lexis-nexis.com (Bob Gerardy) writes:
> Thomas pointed out in a later item on the thread that we can add rock
> phosphate to help replace the P removed, rather than some soluble
> form, and I concur with that approach. My only point is that the garden
> is not SELF sustained, if we are adding outside material from any
> source, no matter how acceptable.
>
> Someone, it may have been Thomas again, also brought up the
> example of a forest, which keeps growing big trees, etc. That is
> quite in line with my point. Animals eat the plants, other animals
> eat animals, all within the forest, but eventually the animals die and
> their remains are returned to the soil. That is not the case with a food
> garden. The forest is a closed system (mostly), the garden is not.
> Even that is somewhat naive. Rain washes minerals from the mountains
> down to the forest, and carries away some soluble material, so even
> the forest is not entirely closed.
Actually you Julie and I are not disagreeing as much as it might
appear. A self-sustaining garden includes the gardener. We as the
grower become a part of the system, and therefore what we add is not
contradictory to, but rather totlly within the boundaries of
self-sustaining. We work with the soil, with the water, with the
plants, animals, insects etc.
Julie mde the comment tht the body i mostly water. This is quite true.
And the amount of nutrients needed for the garden is tremendously
small if we are composting everything back that we can. N,P, K athe
other needed nutrients are needed in a ppm amount, a minicule rate. It
would be like adding a pound of salt to the whole Atlantic ocean. So,
yes biomass and nutrients are removed, but the amounts re so small,
that very little needs to be put back in addition to the composted
amount.
As per the above system, the forrest is not a closed system any more
than the garden, though in the forest, the full cycle of exchange is
more advanced and has fewer "holes". A purpose behing intensive self
sustainable gardening is to develop as complete an exchange cycle as
possible over time.
--
Thomas C. Waters
twa...@pitt.edu
I always assume someone is gay unless they tell me otherwise.
"When evil men plot, good men must plan. When evil men burn and bomb,
good men must build and bind. When evil men shout ugly words of
hatred,
good men must commit themselves to the glories of love."
Martin Luther King Jr.
******************************************************************
Stavros Macrakis
....A self-sustaining garden includes the gardener....
Hmm, that opens up all sorts of possibilities. Does a self-sustaining
garden also include the Ortho factory?.... :-)
We as the grower become a part of the system, and therefore what we
add is not contradictory to, but rather totlly within the
boundaries of self-sustaining.
Seriously, though, I'm not sure what this is supposed to mean. Why is
adding rock phosphate, "within the bounds of self-sustaining", but
adding superphosphate, say, is not?
And the amount of nutrients needed for the garden is tremendously
small if we are composting everything back that we can. N, P, K
a[nd] the other needed nutrients are needed in a ppm amount, a
mini[s]cule rate. It would be like adding a pound of salt to the
whole Atlantic ocean.
Not quite. A reasonable soil concentration of N is about 50 ppm,
about six drops per gallon. I don't know the exact volume of the
Atlantic Ocean, but 50 ppm would come to something more like a
quadrillion pounds. Of course, much of the N can come from compost.
-s
Thomas C. Waters
macr...@osf.org (Stavros Macrakis) writes:
> Hmm, that opens up all sorts of possibilities. Does a self-sustaining
> garden also include the Ortho factory?.... :-)
Uh, no, it doesn't include the ortho factory..... :-)
> We as the grower become a part of the system, and therefore what we
> add is not contradictory to, but rather totlly within the
> boundaries of self-sustaining.
>
> Seriously, though, I'm not sure what this is supposed to mean. Why is
> adding rock phosphate, "within the bounds of self-sustaining", but
> adding superphosphate, say, is not?
Well, because rock phosphate breaks down slowly and because of
differing forces than superphosphate. In that regard, less ionic
phosphate is lost to leeching and percolation in general. The whole
notion of self-sustaining revolves around the process of nutrient
supply being slow and environment driven, ie at the same pace at which
the nutrients would be absorbed. Truly, that rte can not be
empirically determined since it is dynamic and changes based on a
number of factors, but even a simple experiment can illustrate how most
synthetic fertilizers disolute quicker and are therefore more likely to
be lost to percolation and leeching.
> And the amount of nutrients needed for the garden is tremendously
> small if we are composting everything back that we can. N, P, K
> a[nd] the other needed nutrients are needed in a ppm amount, a
> mini[s]cule rate. It would be like adding a pound of salt to the
> whole Atlantic ocean.
>
> Not quite. A reasonable soil concentration of N is about 50 ppm,
> about six drops per gallon. I don't know the exact volume of the
> Atlantic Ocean, but 50 ppm would come to something more like a
> quadrillion pounds. Of course, much of the N can come from compost.
Sorry my chemical equation wasn't exact enough for you!!!! But my
point is still valid. 50 parts per million is a very very minute
amount!!!!! To even imagine a million gallions of water on the
garden!!!!!
As for your drops and pounds in relation to ppm. All that really would
have to do with concentration and molarity and such,so it is really
pointless to argue.
In many respects, fertilizer can be used and, unlike the use of
synthetic pesticides, is harder to argue against. I still used
chemical fertilizers for the first, oh, 6 or 7 years that I gardened
organically (in relation to pest control). But, as I learned more
about the plant's physiology and how soil chemistry functions, I began
to see that the use of chemical fertilizers were not needed for a
healthy thriving garden. Much much more good was accomplished through
improving soil structure and amount of humus in the soil.
And, the damage from nitrate runoff from farms is not an undocumented
issue. This problem my not be as significant on the home garden level,
but that does not mean it doesn't exist.
The soil environment in an organic garden is a rich, diverse, and
dynamic environment and bursts of excessive concentrations of any
nutrient significantly alter soil populations of orgnisms. When I say
excessive, I mean 200 or 300 ppm instead of the 50 you say is adequate.
I am not BTW, speaking in actual numbers, but merely pointing out a
trend or relationship.
The use of chemical fertilizers could be successfuly used in the home
garden if:
1. The grower has the ability to do frequent and reliable soil testing
to determine current soil levels of nutrients and then calculate how
much to add to meet the needed levels. Few if any home growers have
this ability.
2. The means to spread a calibrated amount that is correct with little
varience. Most spreaders do not offer this level of calibration.
3. The grower fertilizes a little everyday (or at least frequently)
and bases the time of "treatment" on a number of factors, but
especially attuned to current soil moisture and air concentrations.
All of that said, the use of chemical fertilizers is less of a serious
problem in the home garden than the use of synthetic pesticides. If a
grower wanted to move towards organic or self sustainable growing,
giving up pesticides is more important than giving up synthetic
fertilizers.
Stavros Macrakis
C. Waters) said:
> ...N, P, K a[nd] the other needed nutrients are needed in a
> ppm amount, a mini[s]cule rate. It would be like adding a
> pound of salt to the whole Atlantic ocean.
I replied in <MACRAKIS.9...@app3.osf.org>
> Not quite. A reasonable soil concentration of N is about 50 ppm,
> about six drops per gallon. I don't know the exact volume of the
> Atlantic Ocean, but 50 ppm would come to something more like a
> quadrillion pounds....
In article <4kkj83$j...@usenet.srv.cis.pitt.edu> twa...@pitt.edu
(Thomas C. Waters) countered:
Sorry my chemical equation wasn't exact enough for you!!!!
A factor of a quadrillion off does seem a bit... inexact... by
anyone's standards.
...But my point is still valid. 50 parts per million is a very
very minute amount!!!!! To even imagine a million gallions of
water on the garden!!!!!
Why do you need to imagine a million gallons of water on the garden?
As for your drops and pounds in relation to ppm. All that really would
have to do with concentration and molarity and such,so it is really
pointless to argue.
Consider one inch of water on 400 square feet (a week's water for my
garden). That's 250 gallons. 50ppm (i.e. 50mg/liter) of 250 gallons
is 1.67 ounces of N. If you're using a 20-10-20 formulation, that's a
little over half a pound of fertilizer (1/0.20 * 1.67 = 8.35). Not so
complicated. And not so minute.
... bursts of excessive concentrations of any nutrient
significantly alter soil populations of orgnisms....
Fine.
When I say excessive, I mean 200 or 300 ppm instead of the 50 you
say is adequate.
OK, then you agree that 50 ppm does not cause problems?
I am not BTW, speaking in actual numbers, but merely pointing out a
trend or relationship.
Um, yes, well, maybe that's safer if factors of a quadrillion or so
don't faze you (shades of Rxxxld Rxxgxx!). But I don't see how to
have an intelligent discussion of the subject without trying to be
more or less accurate about the numbers involved.
The use of chemical fertilizers could be successfuly used in the home
garden if:...
2. The means to spread a calibrated amount that is correct with little
varience. Most spreaders do not offer this level of calibration.
If you use soluble fertilizer in your irrigation system, you can get
quite reliable and even fertilization rates.
3. The grower fertilizes a little everyday (or at least frequently)
and bases the time of "treatment" on a number of factors, but
especially attuned to current soil moisture and air
concentrations....
Again, if you supply the fertilizer in the irrigation water, you
don't need to worry much about soil moisture. I'm not sure what you
mean by air concentrations -- do you mean O2 concentration in the
soil? If so, how does that affect fertilizer rates?
-s
Thomas C. Waters
replies to your recent post.
In article <MACRAKIS.96...@app3.osf.org>
macr...@osf.org (Stavros Macrakis) writes:
> Why do you need to imagine a million gallons of water on the garden?
Wel I suggested this as an example. It isn't too hard to imagine 50
gallons, the amount of N that would be applied in 1 million gallons of
water. One problem with your argument below is that you are mixing
apples and oranges. When you say 1.67 oz N, what does that really mean
since Nitrogen is neve in a N form but always in compound with
something else? Sure 1.67 oz doesn't sound like much, but in relation
to what.......
And, none of your math really means much in the big picture. Even if
the half pound of fert is the amount we are talking about, that IS a
very small amount of fert to apply over a 400 sq ft area. Having
taught as long as I have and taught as many students about
fertilization, I know just how hard this is. A person buys a 5 pound
or 10 pound or bigger bag of Fert. How many have a scale there at the
garden to weigh out their fert??? Not too many that's for sure. So
what happens?? We guesstimate. There goes adequate measuring out the
window!!! We once did a calibration of a set of six spreaders we
owned, and no two dropped the same amount of fert in same space!!!!
Some dropped too much, others not enough.....
Now to drop 1.67 oz........ :-)
> As for your drops and pounds in relation to ppm. All that really would
> have to do with concentration and molarity and such,so it is really
> pointless to argue.
>
> Consider one inch of water on 400 square feet (a week's water for my
> garden). That's 250 gallons. 50ppm (i.e. 50mg/liter) of 250 gallons
> is 1.67 ounces of N. If you're using a 20-10-20 formulation, that's a
> little over half a pound of fertilizer (1/0.20 * 1.67 = 8.35). Not so
> complicated. And not so minute.
Is that N in the form NH4?? or NO2- or NO3_ or another form??? You
know it will make a difference.....
Another problem with all this, is the duration we are talking about.
If you go back to the earlier posts, you'll discover that I commented
at length about percoltion and leaching. No matter how much or how
little we need to apply to reach a certian soil level, soil is a
dynamic environment quickly changing or easily changeable.So, even when
we apply the half pound of fert, we are not assured that most or even
any of it will reach the plant (though in all probability at least some
will).
But, there is another BIG BIG problem with your comments given your
earlier post. You talkied about superphosphate in relation to rock
phosphate (which I mentioned) P and N are very different nutrients, one
is held in the soil by both OM and clay while the other is not, and P
is needed at different quantities at different times etc. Different
factors make one available or inavailable. So, now using N for your
math doesn't speak to the issue of why rock phosphate instead of super
triple phosphate at all.
> ... bursts of excessive concentrations of any nutrient
> significantly alter soil populations of orgnisms....
>
> Fine.
>
> When I say excessive, I mean 200 or 300 ppm instead of the 50 you
> say is adequate.
Well the 50ppm was your number, not mine. I just chose to talk using
it since you brought it up, I never said it was either adequate or
inadequate.
Except when using a water soluable fert (the worst kind for the veg
garden from a purist organic perspective), it would be impossible to
determine just how many ppm were present. Since we are talking
rec.gardens, here, I *THINK* few have the ability to measure in such
minute amounts. Feel free to try and argue using such rhetoric, but
there is no real practical application to be derived from such numbers.
But, you can try a little experiment. Take your water soluable fert
and mix it 10 times too strong (500 ppm vs 50 ppm) and water a potted
tomatoe. Water till it begins to drip from the bottom (bring soil
moisture level up to full capacity, or in other words, we know that
soil water is 500ppm N). The tomatoe set in the sun will soon wilt big
time. Now, drench it with water, till you leach all the excess fert
out of the soil. It won't take much, only enough to replace the full
moisture capacity of the soil. N is not held in the soil at all except
in soil moisture. Therefore, any heavy rain or watering drastically
affects available N.
Now, about those soil microbes, oranisms that are required for healthy
soil, in a self-sustaining garden. Yes, a four to ten fold increase in
any salt (fertilizer is a salt BTW) is going to dramatically alter soil
microbe populations. Now, after the excessive salt is removed, the
microbe population will again develop, but the harsh ups and downs of
that microbe population has negative impact on the overall soil
dynamics.
> OK, then you agree that 50 ppm does not cause problems?
No, I don't agree. IMHO attempting to sound scientific with ppm
numbers as if we, in the garden can measure that way is rediculous.
You introduced the number 50ppm. The actual number really isn't
important in understanding the principles involved.
> I am not BTW, speaking in actual numbers, but merely pointing out a
> trend or relationship.
>
> Um, yes, well, maybe that's safer if factors of a quadrillion or so
> don't faze you (shades of Rxxxld Rxxgxx!). But I don't see how to
> have an intelligent discussion of the subject without trying to be
> more or less accurate about the numbers involved.
Thanks but I've battled enough on this topic, I don't need to reply to
this type of attack. If you want to talk about numbers, then use
numbers that are meaningful to a home gardener. But, no matter what
the numbers are the principles I am speaking of apply. Fertilizer is
(chemically) a salt. Applying a heavy amount of a salt will surely dry
up soil microbes and organisms. It really is that simple. N, since it
isn't held in te soil except in ssome ion forms with oxygen NO3- and
NO2-, is continually in solution and always open to percolation and
leaching.
> The use of chemical fertilizers could be successfuly used in the home
> garden if:...
>
> 2. The means to spread a calibrated amount that is correct with little
> varience. Most spreaders do not offer this level of calibration.
>
> If you use soluble fertilizer in your irrigation system, you can get
> quite reliable and even fertilization rates.
Well only if you can then control water added to the soil since every
added amount of water will wash the N out of the soil. Yes, you might
be able to apply the correct amount by knowing how much to mix, having
a good ability to mix it with water and a way to time the watering so
you know exactly how much water you have applied. In a greenhouse this
is quite easy and in a greenhouse this type of fertilization is the
best way, but not in the home garden.
> 3. The grower fertilizes a little everyday (or at least frequently)
> and bases the time of "treatment" on a number of factors, but
> especially attuned to current soil moisture and air
> concentrations....
>
> Again, if you supply the fertilizer in the irrigation water, you
> don't need to worry much about soil moisture. I'm not sure what you
> mean by air concentrations -- do you mean O2 concentration in the
> soil? If so, how does that affect fertilizer rates?
Well, you do have to be concerned about soil moisture levels. You
could fert using your form of irrigation and then a big rain comes and
changes everything. In a greenhouse using a mixed, known soil mix and
controled watering your approach is fine, but not in the outdoor home
garden, and especially not for the average gardener. Soil moisture and
soil air concentrations as well as amounts are important, but the
amount of importance depends upon the soil type. In clay and heavy
soils, where the structure has fewer macropores, air concentrations are
greatly reduced, and weak but very frequent waterings therefore mean
higher concentrations of N in the soil in relation to other nutrients
such as O2. That is one reason why different types of soils respond to
fertilizer differently.
In fact, soil structure probably affects plant nutrition more than the
amont of fert a gardener applies. Since micropore and macropore space
as well as clay and OM content al affect how much N (in ion form is
held in the soil) it is difficult or impossible to be sure that the
50ppm you are putting into the soil is not staying in solution and
going stright through the soil and into a stream somewhere. Some of it
may be "grabbed" by a root, but absorbtion happens due to both
diffusion and osmosis and the rates of these are determined by water
and nutrient concentrations inside the root no matter what the soil
concentration is.
In a greenhouse setting where the soil structure is manufactured by
mixing soil with perlite or vermiculite and sand and such, and where
you have table after table of extremely uniform soil structure, a
irrigation system like you describe is perfect, but that isn't the case
in the garden.
A basic soil chemistry class at a land grant(US) institution wil
provide a whole set of experiments which illustrate these principles.
BTW, I NEVER said that chemical fert could never be used, nor am I
saying that in theory, some of your points are not valid, but in
realistic terms, there are too many variables in the home garden to
make it as simple as you try to make it.
But, consider the forrest floor. Plants there thrive, depending upon
light levels that is. All their nutrients are provided by rotting
decaying plant material and manure (of sorts). In other words, compost
is totally able to provide adequate fertilization witj out the need for
chemical or easily soluable fertilizers, and compost provides for and
in fact creates a less fluctuating soil environment for sol microbes
and other organisms.
There may be a place for the use of slow release ferts like osmocote,
in the garden. However, even compared to it, compost and other forms
of nutrients more similar to what is found in a natural growing
environment is a better alternative.
IMHO, chemical fertilizers are good for solving short term nutrient
deficiencies where a quick solution to the problem is needed, but it is
not as good as some compost and other more natural forms for the long
range.
Stavros Macrakis
Your answers are frustrating to me because you certainly know a lot
(and I am learning from it), but at the same time you say some
ridiculous things, which diminishes your credibility. Now, back to
the discussion:
-s
In response to twater+'s article <4kkj83$j...@usenet.srv.cis.pitt.edu>,
I said in article <MACRAKIS.96...@app3.osf.org>:
> Why do you need to imagine a million gallons of water on the garden?
In article <4l1qih$m...@usenet.srv.cis.pitt.edu> twa...@pitt.edu (Thomas C. Waters) writes:
...It isn't too hard to imagine 50 gallons, the amount of N that
would be applied in 1 million gallons of water....
Come on now, both 50 gallons of N and 1 million gallons of water are
ridiculously large quantities. I gave a more realistic example, about
which you say:
... One problem with your argument below is that you are mixing
apples and oranges. When you say 1.67 oz N, what does that really
mean since Nitrogen is neve in a N form but always in compound with
something else? Sure 1.67 oz doesn't sound like much, but in
relation to what.......
I _explicitly_ converted the 1.67oz of N to a standard synthetic
fertilizer formulation, 20-10-20. It comes to a half pound. A very
easy-to-imagine quantity.
And, none of your math really means much in the big picture. Even
if the half pound of fert is the amount we are talking about, that
IS a very small amount of fert to apply over a 400 sq ft area.
Sure, I agree that spreading 1/2 pound dry over 400 ft2 is going to be
hard. Which is why I wasn't suggesting doing it.
...How many have a scale there at the garden to weigh out their
fert??? Not too many that's for sure....
I would certainly agree with you that they should. I don't cook
without a measuring cups and balance; I don't see why I should garden
without them.
> ...50ppm (i.e. 50mg/liter) of 250 gallons is 1.67 ounces of N....
Is that N in the form NH4?? or NO2- or NO3_ or another form???
know it will make a difference.....
Elemental N. I am perfectly aware that ammonium, nitrate, and urea
(e.g.) are reacted to differently.
...No matter how much or how little we need to apply to reach a
certian soil level, soil is a dynamic environment quickly changing
or easily changeable.So, even when we apply the half pound of fert,
we are not assured that most or even any of it will reach the plant
(though in all probability at least some will).
Agreed. But it will be close enough, no? And as long as the 50ppm
are not harming the soil organisms (are they? I don't think you've
answered yet), you have that source as well.
But, there is another BIG BIG problem with your comments given your
earlier post. You talkied about superphosphate in relation to rock
phosphate (which I mentioned) P and N are very different nutrients, one
is held in the soil by both OM and clay while the other is not,
I am aware of that. But the big difference here isn't between rock
phosphate and superphosphate, but between both of those and the
calcium phosphates as found in bone meal. In an acid soil, the former
quickly become unavailable, but the latter less so. Isn't that right?
Since I have an acid soil, I use bone meal as my phosphate source.
Well the 50ppm was your number, not mine. I just chose to talk using
it since you brought it up, I never said it was either adequate or
inadequate.
It's a number in the right ballpark. It's a little high as a soil
solution concentration, and maybe a little low as a fertilizer
concentration. I think it's worth discussing what the consequences of
50ppm are.
Except when using a water soluable fert (the worst kind for the veg
garden from a purist organic perspective),
Please, let's keep the purism out of it (that's just a recipe for
flame wars) and just discuss the plants and the soil.
...it would be impossible to determine just how many ppm were
present. Since we are talking rec.gardens, here, I *THINK* few
have the ability to measure in such minute amounts.
I don't see why you'd have to measure the soil solution
concentration. As I showed above, _applying_ 50ppm is pretty
straightforward.
...N is not held in the soil at all except in soil
moisture. Therefore, any heavy rain or watering drastically affects
available N.
Yes, I am aware of that.
Now, about those soil microbes, oranisms that are required for healthy
soil, in a self-sustaining garden. Yes, a four to ten fold increase in
any salt (fertilizer is a salt BTW)...
Yes, agreed, although different fertilizers have different salt
indices.
> OK, then you agree that 50 ppm does not cause problems?
No, I don't agree. IMHO attempting to sound scientific with ppm
numbers as if we, in the garden can measure that way is rediculous.
If you _apply_ 50ppm in the irrigation water, presumably the soil
solution is going to be _at most_ 50ppm. So, let me rephrase the
question: is _applying_ 50ppm N in irrigation water going to cause
problems?
Thanks but I've battled enough on this topic, I don't need to reply to
this type of attack. If you want to talk about numbers, then use
numbers that are meaningful to a home gardener.
You were the one who introduced a pound of salt in the Atlantic Ocean!
And you're claiming that that's meaningful to the home gardener!?
Well, you do have to be concerned about soil moisture levels. You
could fert using your form of irrigation and then a big rain comes
and changes everything.
Yes, this is true. But then, it's true of whatever nitrates your soil
microorganisms are producing, too, isn't it?
But, consider the forrest floor. Plants there thrive, depending
upon light levels that is. All their nutrients are provided by
rotting decaying plant material and manure (of sorts). In other
words, compost is totally able to provide adequate fertilization
witj out the need for chemical or easily soluable fertilizers,...
Yes, this is certainly true. However, I am interested in creating an
_unnatural_ situation in my garden, with a much higher concentration
of plant material, and plant material of my choice! I do go walking
in woods, and I certainly enjoy that, but I do not want my tiny city
garden to have the same low density of interesting plants. In a
natural setting, there wouldn't be very much vegetation under mature
maple trees, would there? So I am trying to use every means at my
disposal to make the environment under them hospitable to other
plants. I am improving the soil with compost, bonemeal, and
greensand. I am irrigating and fertilizing. I am weeding. And of
course I'm selecting plants which have some chance of surviving
relatively low light.
-s
Thomas C. Waters
> Sure, I agree that spreading 1/2 pound dry over 400 ft2 is going to be
> hard. Which is why I wasn't suggesting doing it.
Well I'm sorry if I loose my temper a little here tonight.
This whole discussion started when I said that the amount of fert
needed was extremely small. To which you replied that I was wrong, it
wan't so small.
And now you are saying that 1/2 lb is a small amount difficult to put
down accurately.
Why didn't you just agree with me in the first place since I was right?
Jeez.
> Elemental N. I am perfectly aware that ammonium, nitrate, and urea
> (e.g.) are reacted to differently.
Well, we never put down element N on the garden. Can't by it that way.
> ...No matter how much or how little we need to apply to reach a
> certian soil level, soil is a dynamic environment quickly changing
> or easily changeable.So, even when we apply the half pound of fert,
> we are not assured that most or even any of it will reach the plant
> (though in all probability at least some will).
>
> Agreed. But it will be close enough, no?
Close enough??? Who knows.. it may be or may not. The point is that
ANY amount that doesn't get quickly absorbed is lost to leaching or
percolation and ends up in run off damaging streams and other water
areas. Since we have no way of knowing how much actually gets to the
plant, we have no idea how successful we are or are not being.
Might as well just wave a wand over the garden.. it might add as much N
as our fertilizzation is.... (that was a joke)
>?And as long as the 50ppm
> are not harming the soil organisms (are they? I don't think you've
> answered yet), you have that source as well.
I don't understand what you are saying here. What do you mean you have
that source??? Source for what???
BTW, I believe what I said about salts answers the question about
harming soil microbes.
> But, there is another BIG BIG problem with your comments given your
> earlier post. You talkied about superphosphate in relation to rock
> phosphate (which I mentioned) P and N are very different nutrients, one
> is held in the soil by both OM and clay while the other is not,
>
> I am aware of that. But the big difference here isn't between rock
> phosphate and superphosphate, but between both of those and the
> calcium phosphates as found in bone meal. In an acid soil, the former
> quickly become unavailable, but the latter less so. Isn't that right?
> Since I have an acid soil, I use bone meal as my phosphate source.
Too bad I didn't keep your earlier post. You asked specifically what
was the difference between you putting down tri-phosphate compared to
the rock phosphate that I mentioned. I have only replied to what you
have specifically written. If you wanted to talk about bone meal, you
shoulda said so. I think you are just trying to confuse the
subject....
P was the nutrient we first began discussing. Then you brought N into
the picture. N however isn't held in the oil very easily due to the
ions it forms, where P is held easier in the soil and remains more
available due to that.
Yes, pH affects nutrient availability, but even when the pH is
satisfactory, N is leached away. You are introducing another variable
rather than discuss the one you were attempting to argue bout allready.
Jeez.
> Well the 50ppm was your number, not mine. I just chose to talk using
> it since you brought it up, I never said it was either adequate or
> inadequate.
>
> It's a number in the right ballpark. It's a little high as a soil
> solution concentration, and maybe a little low as a fertilizer
> concentration. I think it's worth discussing what the consequences of
> 50ppm are.
I don't. Few home gardeners are able to successfully measure to aquire
it, and since N isn't held in the soil, the amount you put in has
little to do with how much is actually available to the plant. We have
no way of determining what the consequences are or are not in a garden.
> Except when using a water soluable fert (the worst kind for the veg
> garden from a purist organic perspective),
>
> Please, let's keep the purism out of it (that's just a recipe for
> flame wars) and just discuss the plants and the soil.
Look at the subject line. This is a discussion about Organic methods
in coparison to non-organic methods. And.. I believre I have
discussed the soil to a far greater extent than you.
> I don't see why you'd have to measure the soil solution
> concentration. As I showed above, _applying_ 50ppm is pretty
> straightforward.
But since N isn't held in the soil, the amount you add has nothing to
do with how much is available to the plant!!!! That's why. One person
could be dumping 800ppm on the garden but due to the soil structure,
watering habits, amount of rain fall etc, *NONE* of it may be getting
to the plant. The amount you put down isn't all that important when we
are talking about how much a plant needs.
> ...N is not held in the soil at all except in soil
> moisture. Therefore, any heavy rain or watering drastically affects
> available N.
>
> Yes, I am aware of that.
>
> Now, about those soil microbes, oranisms that are required for healthy
> soil, in a self-sustaining garden. Yes, a four to ten fold increase in
> any salt (fertilizer is a salt BTW)...
>
> Yes, agreed, although different fertilizers have different salt
> indices.
Fertilizer, by its chemical formulation is a salt, no matter what its
indice!!!!
Some chemicals are metals, some are alcohols, some are acids, etc.
All ferts are salts.
> > OK, then you agree that 50 ppm does not cause problems?
>
> No, I don't agree. IMHO attempting to sound scientific with ppm
> numbers as if we, in the garden can measure that way is rediculous.
>
> If you _apply_ 50ppm in the irrigation water, presumably the soil
> solution is going to be _at most_ 50ppm.
But we can't assume this in a garden soil!!!!!!! We can... but it is
stupid to.
And what the level is at most is really unimportant for plant growth.
What is important is how much is available.
So, let me rephrase the
> question: is _applying_ 50ppm N in irrigation water going to cause
> problems?
We can not know. There are too many variables in the garden soil that
make attributing a problem to one or the other difficult if not
impossible, at least without seeing the soil. Did you read my post
about greenhouse soils vs garden soils??? Please do.
But consider it another way:
Here is your garden soil. It rained really hard yesterday, heavy rains
drenching the soil. You have a fairly porous sandy loam. No N has
been left in the soil from your irrigation-added fert, since it is by
its nature water soluable.
So today, you don't want to water since it is already too wet. So no
new N is added.
The ppm N is basically "0"
Next day is a hot sunny day. You water with your irrigated-added N,
and the soil is now about 50ppm N. But the conc. N in the root is
lower than that since no N was added the day before. Water moves via
osmosis, and nurents move via osmosis and diffusion. Little N is
moving into the root to balance the Conc of N, but no water is since
the Conc water is so much greater within the rot than outside the root,
but the suuny day is causing much evaporation through the leaves.
Since water is not able to easily pass into the root due to water conc
in and outside root, and hifg N outside root is keeping water from
flowing in, the plant wilts.
Now, that may seem hard to follow, but read through it a few times
before posting.
Or consider this:
The soil the day after it rains is now 0ppm N. When you fert, it goes
immediately up to 50ppm, a 50 fold increase. THAT has to be difficult
on soil microbes!!!!! It is only NOT difficult when you are able to
keep a consistant amount in the soil, so the microbe level is ued to
it. The difficulty comes in the fluctuations, and in the garden soil,
these are uncontrolable due to a number of factors I mentioned above.
> You were the one who introduced a pound of salt in the Atlantic Ocean!
> And you're claiming that that's meaningful to the home gardener!?
Dah.. it was an illustration to show how mnute the amount of nutrients
needed is. Yes, I find illustrations that can be visualized to be
helpful to the home gardener.
> Well, you do have to be concerned about soil moisture levels. You
> could fert using your form of irrigation and then a big rain comes
> and changes everything.
>
> Yes, this is true. But then, it's true of whatever nitrates your soil
> microorganisms are producing, too, isn't it?
No it isn't. With using compost as a means of supplying N or other
forms on organic N the change to the soil moisture levels of N (or any
nurtrient) are significantly less affected. Yes, it is true with all
chemical ferts however. Please remember, I have been speaking about a
self-sustainable gardening approach from the beginning of this thread.
I haven't suggested using chemical ferts as the primary source of fert.
In fact I have spoken against it. Drip irrigation or any other form
of chem/synthetic fert.
> Yes, this is certainly true. However, I am interested in creating an
> _unnatural_ situation in my garden, with a much higher concentration
> of plant material, and plant material of my choice!
Consider growing in bio-intensive beds using all organic processes.
You can achieve a four times the yield in the same amount of space
using bio-intensive practices and no chemicals. No chemicls means
little to no leaching of nutrients to harms the environment. A four
fold increase in yields is enough to please any gardener.
I doubt you can get any increase in plant material in your un-natural
garden over my bio-intensive garden!!!
I do go walking
> in woods, and I certainly enjoy that, but I do not want my tiny city
> garden to have the same low density of interesting plants.
The low density of plants has more to do with light levels not
fertiliztion levels. I only have a small city plot too. IMHO, you
need to learn some basic biology. Learn a little about light and soil
and plant processes. the method of fertilization in the forrest is far
richer than you achieve!!! And, far better for both the plants and the
environment.
>In a
> natural setting, there wouldn't be very much vegetation under mature
> maple trees, would there? So I am trying to use every means at my
> disposal to make the environment under them hospitable to other
> plants.
Well, since light is the single most important growth regulator.. no
matter how much you try and control the fertilization, you aren't going
to accomplish very much!!!
>I am improving the soil with compost, bonemeal, and
> greensand. I am irrigating and fertilizing. I am weeding. And of
> course I'm selecting plants which have some chance of surviving
> relatively low light.
Well, if you plant using a bio-intensive approach and quit fertilizing
you will eliminate the weeds. You will probably minimize insect
problems too. I bet though that you could dramatically increase the
amount of compost you are adding, and mulch mulch mulch!!!!! What is
the soil structure like??? How porous is the soil?? How much are you
compacting it???? These will do more good than any time wasted on
irrigating fertiliation systems, especially in a lower light setting.
Allyn Weaks
question for Thomas:
Since you teach this stuff, what texts do you use? What other references
do you recommend? I've started trying to learn more about soil chemistry
and ecology because of my interests in native plants, and my chosen task
of turning highly compacted, near-dead urban turf-grass soil into a
mini-'forest floor' in hopefully less time than my remaining lifetime.
There are certainly a heck of a lot of complications, which is presumably
why I've been seeing some rather suspect chemical overgeneralizations and
handwaving in this discussion...it's hard to make some conclusions look
like they follow from the premises when one has to leave out most of the
premises and intermediate reasoning. So rather than have you spend weeks
and months typing, how about a few good book titles?
--
Allyn Weaks al...@u.washington.edu
PNW Native Wildlife Gardening: http://chemwww.chem.washington.edu/natives/
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Thomas C. Waters
al...@u.washington.edu (Allyn Weaks) writes:
> I've been following the entertainment here for awhile, and I have a
> question for Thomas:
>
> Since you teach this stuff, what texts do you use? What other references
> do you recommend? I've started trying to learn more about soil chemistry
> and ecology because of my interests in native plants, and my chosen task
> of turning highly compacted, near-dead urban turf-grass soil into a
> mini-'forest floor' in hopefully less time than my remaining lifetime.
> There are certainly a heck of a lot of complications, which is presumably
> why I've been seeing some rather suspect chemical overgeneralizations and
> handwaving in this discussion...it's hard to make some conclusions look
> like they follow from the premises when one has to leave out most of the
> premises and intermediate reasoning. So rather than have you spend weeks
> and months typing, how about a few good book titles?
I'm sorry to take so long to reply to you Allyn. I've been so busy,
and there just hasn't been time. I don't have much to offer you today
either in terms of texts, but will pull out some things and post them
over the weekend I hope. I'm not sure if washington.edu is or not, but
if it is a Land Grant Institution, call someone over in the soil
science or agronomy dept. and ask what they use for their basic soil
science text. The one I use dates bck to my college days (grad 1982)
but dirt is still dirt. :-)
I think the complications only come if/ when we try and view individual
things like fertilization without recognizing how interconnected all
growing processes are. When we talk about one thing like water needs,
or fertilization needs, as if there were no affecting variables, we 1)
miss the real point, and 2) get confused.
As you may have figured out, I type with three fingers and so yes, I
would spend weeks or months trying to answer long questions, bhut there
are many here who would love to learn I bet and many expert gardeners
with plenty of experi to share, so ask away.
Substantially altering a soil can take time, but perhaps the focus on
what it ought to be is missing the real pleasure of the journey to get
there. All soil is what it is, and what change we attempt is just part
of a greater change happening with or without us. Plants are amazing
beings!!! Ever notice how even weeds can seem to thrive in horrendous
soil???? Plants can do OK without too much help from us.
Do you want to turn your yard area into a natural pasture-like field???
When you say forrest floor... what is it about that environment do you
want to emulate???
I'd say get ahold of Bountifl Gardens seed catalogue and some of their
publications. They give a pretty thorough explanation of green manures
and cover crops and which can help what type of soil and why.
Looking forward to hearing more from you here in rec.gardens