Question
what are the harmful effects of chemical fertilizers;potassium fertilizers;nitrogen and phosphatic fertilizers?

Answer
This could be a very long answer.  I'll try to summarize without writing a book, and if you want elaborations on one in particular we can focus on that one and expand as needed on any others.

First, there's the environmental damage and impact on human health caused by chemical N-P-K fertilizers.

Then, there's the problems of overuse.  Excessive doses of some nutrients is a direct cause of other nutrient deficiencies.

And there's the build-up of chemical Salts.  Because these fertilizers are by definition SALTS.  Everyone knows Salt is BAD for agriculture.

On top of all this is the terrible toll that fertilizer manufacturing takes on the environment and the people who live near the factories.  They pollute; they're dangerous.  Remember the Bhopal fertilizer plant explosion in India in 1984?  The Toulouse fertilizer plant explosion in France in 2001?  On our own shores, the worst accident involving fertilizer took place in 1947 in Texas, when 600 people were killed and 3,500 people were injured; it was part of the testimony presented in July 2005 before the Senate Homeland Security Committee, which was studying national security risks:

www.globalsecurity.org/security/library/congress/2005_h/050713-poje.pdf

Let's look first at the ingredients in a balanced fertilizer: N-P-K.

N, Nitrogen, is the most common element in our atmosphere.  It comes in different forms: Elemental N, NO3- (Nitrate), NO2 (Nitrite), NH4+ (ionized Ammonia), NH3+ (poisonous Ammonia gas) and others.  Nitrogen is also an essential nutrient; all plants and animals need it to survive.  It's essential to the Chlorophyll molecule.  

Too much, or the wrong kind of N, will damage or kill these organisms.

news-service.stanford.edu/news/1998/august26/yaqui.html

N is especially toxic to fish and invertebrates.  It's also toxic to humans; people who depend on rural, private wells for their water source have one of the higher rates of a condition called Methemoglobinemia, aka Blue Baby Syndrome, which damages blood cells and is traced to high Nitrates.

Articles in Science Magazine submitted by the International Nitrogen Initiative last May inspired 'Reactive Nitrogen: The Next Big Pollution Problem' on the Wired Science website.  It describes a litany of problems and warns us, 'Nitrogen pollution could eventually render entire stretches of ocean dead, as is now the case in the Gulf of Mexico, where fertilizer runoff has created a 5,800 square mile dead zone.'  Here's the URL:

blog.wired.com/wiredscience/2008/05/reactive-nitrog.html

More data appears in an essay posted by a company in New Jersey, Alpha Water Systems, titled 'Nitrate Pollution of Groundwater'.  You can read it online:

www.reopure.com/nitratinfo.html

None of this is new.  It's just worse.

And that's just the N.

Unlike Nitrogen, Phosphorus and Potassium are immobile in Soil.

Feldspars and Micas contain most of the Potassium in our Soil.  K in fertilizers is almost always applied as Potassium Chloride from mines in Canada.

K dissolves in Water.  P does not.

Instead, it binds to Soil particles and stays put until some nice microbe comes along and un-locks it.  Clay Soils tend to keep the strongest grip on it; Sandy Soils are looser and let it drizzle through.

Phosphate and Potash fertilizers don't just raise the chemical P and K levels; they also add damaging Soil Salts.  And although most Soils in the U.S. have perfectly adequate levels of Phosphorus and Potassium, and even though they don't need any more from your fertilizer, people use them anyway.  This is a problem because too much Phosphorus locks other nutrients OUT of plants.

Iron and Zinc deficiencies are common in Soil over-loaded with non-dissolving P.  A fatal disease in livestock called 'Grass Tetany' -- a complex condition linked to Mg deficiency in cows and other ruminants -- is examined by French author Andr?Voisin: 'Excessive and repeated dressings of Potassium fertilizers cause Magnesium deficiencies in plants, particularly Grasses...'  It's even bad for the animals that depend on them; they too develop Mg deficiency:

www.soilandhealth.org/01aglibrary/010106voisin/010106gtchap6.html

Organic Phosphates provide energy for chemical reactions in plant and animal growth and cell reactions.  But too much and you end up with growth out of control.

When this happens in a lake, you find so much growing going on that they run out of Oxygen; you end up with a lot of dead plants and animals.

Phosphate pollution is so bad in some areas, people are pushing for a 'Phosphate Fertilizer Act' to deal with it.  Phosphorus would be legal only if a Soil Test showed it was needed; only if you were planting new Seed or installing new Sod; or if you're a licensed greenskeeper at a golf course.

You can see how hard fertilizer companies would push to block this law.  Their profits depend on getting people to use fertilizer ALL the time, not just when they need it.

Making Phosphate fertilizer is no picnic, either.  That's a big problem in Florida, where it's a billion dollar industry.  Phosphate fertilizer contains radioactive lead and polonium.

Mine the Phosphate and you end up with radioactive byproducts.  As environmentalist George C. Glasser points out, 'Phosphate fertilizer manufacturing and mining are not environment friendly operations... People living near the fertilizer plants and mines, experience lung cancer and leukemia rates that are double the state average.'  You can read his article, 'Fluoride and the Phosphate Connection', in the online Pure Water Gazette:

www.purewatergazette.net/fluorideandphosphate.htm

Potassium (K) is essential for plant growth.  K is generally not considered an environmental problem; in parts of the world where high levels were recorded, industrial waste (and not fertilizer) was blamed.  Plants absorb K very efficienty when it's dissolved in the water in your Soil.  As with P, too much K in your Soil will chemically lock out other important micronutrients.  Calcium and Magnesium are 2 elements upstaged by too much K in Soil.

Now, we all know that Salt damages plants.  A Chemical fertilizer is, technically, a Chemical Salt: an Ionic Compound.  It can be produced by the reaction of an Acid and a Base; by combining a Cation (positively charged Ion) and an Anion (negative charged Ion) or a Metal and an Acid.

A Salt gets its name from the Cation, followed by the name of the Anion.  NaCl - Sodium Chloride, aka Table Salt, is a Sodium Cation bonded to a Chloride Anion.  (NH4)2SO4 - Ammonium Sulfate, the preferred N fertilizer for Lawns and Golf Courses, is an Ammonium Cation and a Sulfate Anion.  Ca(NO3)2 - Calcium Nitrate, a Calcium Cation and a Nitrate Anion.  CO(NH2)2 is Urea, the most inexpensive Nitrogen fertilizer, made of Carbon Dioxide (CO2) and Anhydrous Ammonia (NH3) (Ammonia bonds directly with Acids to form 'Ammonium Salts').  

That, in a very large nutshell, is the problem with chemical fertilizers.  Any questions?

THE LONG ISLAND GARDENER