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Nashville, TN

Here's a little background info an the manufacture of commercial fertilizers:

Nitrogen: manufacturers capture N from the atmosphere, combine it with H from natural gas and create anhydrous Ammonia. Which reacts in ionization react with water (aka dissolves rapidly). They also creat the Anhydrous ammonia with byproducts of coke ovens - Sulfuric Acid is used to remove ammonia evolved from coal.

Phosphate: Phosphate rock has sulfuric acid added to it - to create phosphorus solution.

Both of the elements are 'stabilized' into a crystalline 'salt' lattice/structure for easy transport and water solubility. Both of these elements are rapidly leached from soils (in those forms) and create Phosphate and Nitrate runoff into the groundwater, streams and lakes.

In most 'soils' college courses, it is taught that after many decades of chemical fertilizing, salts will accumulate in those soils and affect the overall quality of those soils. This is more pronounced in dryer climates/regions.

Farmers can limit the dangers of over-chemical fertiling by adding organic matter and microbes, as well as adjusting pH to approx 7.0-7.4

4/12/2006 11:12:19 AM

Warwood

To moderate that a bit I would say use ferts sparingly and in more diluted forms. The waters are clearing slowly but surely in my region of the earth. I've been a fisherman all my life and see it. "JUST DON"T BE STUPID AND THINGS SHOULD COME OUT OK...lol.
Science Teacher: Dah, what's he thinking. :)
.....as the creative world meets the scientific world, biology and psychology. Words of Wisdom...WOW..lol Don

4/12/2006 2:32:46 PM

Tipp City, Ohio

I would not worry too much about how much the farmer uses. Some large farm operations use planters that test the soil as ferts are applied. The planter then allows an adjusted amount of fertilizer needed to the tested soil at the given location. It saves the farmer a lot since fertilizer and $$$ by using only the fertilizer needed and not just the old rule of thumb as applying xxx lbs per acre.

Now I have also seen very green lawns(no weeds) and carpet like during the months of Jan and Feb as well as the other months. Makes me wonder how much they put down as far as ferts and chemicals compared to the farmer??????

4/12/2006 8:52:14 PM

Kiel WI

Yep, on a per acre basis lawns and gardens get a lot more pesticides and fertilizers than farm fields.

I thought phosphorus bound tightly to soil particles, so it won't leach down through the soil? But it is capable of running off into surface water if the soil washes with it?

4/13/2006 1:55:12 PM

I'm wondering how a farmer is going to adjust the pH of a presumably acidic soil to approximately 7.0 to 7.4 without adding salts.

Lime, as well as most nutrients added to the soil, whether from commercial fertilizers or the south end of a north bound bovine, are in the form of soluble salts. You can just as easily create too much soil salinity by the addition of tons of manure as you can by the addition of commercial fertilizers. It should also be noted that most commercial fertilizers are tightly controlled in terms of analysis, content, and may even be rated in terms of a "salt index," whereas manure may vary widely dependent upon the diet of the livestock producing it.

As with anything, the key is moderation (as opposed to, "if a little is good, a lot must be better"). Moderation may be a difficult concept for giant pumpkin growers to grasp, but I'm betting most can figure it out.

4/13/2006 8:05:03 PM

Kiel WI

I thought ag lime was just ground limestone?

4/14/2006 11:47:57 AM

Calcium carbonate (lime) is a salt. Salt is a much broader term in chemistry than just sodium chloride (table salt) - which is what most folks think of when they hear the term.

4/14/2006 9:23:53 PM

Nashville, TN

Calcium Carbonate is technically a salt - goes into it's ions in water ... Ca binds to the soil particles - generally with the naturally occuring acids (Nitrogen or Sulpur based generally). Carbonate is turned into Carbon dioxide by microbes and is taken up by plant roots.

Pretty much anything that ionizes rapidly in water (dissolves) is covered under the term 'salt'.

As for manure salt. Yes, it contains naturally occuring salts, that are also leached by rain. Though unlike chemical fertilizer-based salts - the salts from animal waste are generally consumed by microbes . (With the exception of large drylot operations that generate copiuos amounts of manure and don't properly dispose of it)

It's interesting that out west - the waste water treatment facilities can usually generate clean enough water - that it's reused for drinking water. The only waste they have problems with (generally speaking) is the chemical runoff (fertilizer/pesticides/ and petroleum-based products) - this type of contaminant is hard to filter out (with microbes, chemicals or other filtration techniques).

4/15/2006 11:17:45 AM

Technically speaking, the fact that calcium carbonate dissociates in water is not why it is considered a salt. Were classification as a salt dependent upon Ksp, you would have to reclassify a host of compounds on either side.

Regarding animal waste, if the salts in the manure are the same (chemically) as those in commercial fertilizers, then the microbial action/reaction to those nutrients is the same. There may be other factors which influence the biological response, and certainly the presence of most microorganisms found in manure is beneficial to the overall health of the soil and its ability to make good use of nutrients from both natural and commercial fertilizers.

I will grant you that anthropomorphic sources of chemicals are often more difficult to deal with in waste treatment. Though the filtration examples listed are incorrect (filtration is a physical separation technique).

An example waste treatment scheme would be pH adjustment, flocculation, and then filtration. If something, such as a chelating agent, is unaccounted for in the waste treatment plan, precipitation may fail. Other chemicals may interfere with flocculation, leaving a very difficult colloidal suspension with which to deal. Man made materials may foul filters, but it is more likely that something would create difficulties with either the precipitation or flocculation reactions, thereby making the semi-treated solution extremely difficult to finish.

4/15/2006 1:40:53 PM

[email protected]

Calcium carbonate is not a salt. If it were, it would be neutral. Salts are minerals that have been combined to result in a neutral charge.

4/15/2006 4:29:41 PM

Calcium carbonate is charge neutral. If it weren't, picking up a bag of lime would be a shocking experience. Calcium carbonate dissociates into ionic species when dissolved in water.

4/15/2006 11:23:50 PM