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western PA

Will ground oyster shells from the feed store affect my soil pH, or will it act like gypsum and not alter it.

4/9/2007 9:58:09 AM

Boulder County Colorado USA planet Earth

I have been wondering the same thing.

4/9/2007 10:16:33 AM

President - GPC

From My reading Oyster shell is a great slow way to increase Ca but is very high in Ph. It is very affordable at Feed stores as they feed it to chickens to increase the strenght of the egg shells. Our Colorado soil is high in lime and high in Ph, making oyster shell not a good thing to add, but back east in acidic soils would be diff.

4/9/2007 10:31:42 AM

western PA

right now my pH is at 7.0. So i guess i should not add any of the oyster shells. right?

4/9/2007 10:35:56 AM

Menomonie, WI (mail@gr8pumpkin.net)

Correct....Oyster shells are basically Calcium Carbonate. Same thing as lime. They are fed to chickens as a source of grit. This allows them to grind up food in their gizzards for digestion.

4/9/2007 10:59:59 AM

western PA

i was looking for an addative that will not effect the pH. i didnt know if putting on too much gypsum would give rise to too much Sulfer in the soil.

4/9/2007 12:52:41 PM

Ontario

I add gysium every fall and spring for the last 5 years, has done nothing to my sulfur levels. I add 100 pounds to 1400 sq ft every fall and another 100 pounds in the spring

drew

4/9/2007 10:27:28 PM

Ctpumpkin@optonline.net

Oyster shells take longer but will eventually raise the pH.

I'm with Drew on the Gypsum. The amount of sulfur is insignificant. Beside, plants need sulfur too.

4/9/2007 11:29:00 PM

Eugene, OR

Steve, noticed your post on sulfur. Correct me if I'm wrong but isn't most gypsum around 20% sulfur? I've added probably over 1000 pounds of gypsum to my patch over the past few years and my sulfur levels have gone from under 100 to over 1500 ppm. If my math is right, I've added about 2178 ppm of sulfur(based on 2000 ft^2). Not sure how quickly sulfur leaches but looking at my actual sulfur levels compared to what the math says it should be, I'd say that's not unreasonable.

There seems to be a bit of conflicting info on gypsum and sulfur. If we're adding hundreds of pounds of gypsum for calcium and it's 15-20% sulfur, how can our sulfur levels not rise dramatically as well? I've also read over and over again that gypsum will not affect pH, which it hasn't in my patch, but we also add sulfur to lower pH. How is it that we add sulfur to lower our pH but the sulfur in gypsum has no affect? Are these two different sulfur compounds we're dealing with?

Sorry to piggyback on your thread Vader but I've been wondering this for a while now and it may help answer your questions as well.

4/9/2007 11:54:37 PM

Paradise Mountain, New York

Stay away from oyster shells. I added then to my patch a few years ago. Now my Ph is 7.7 and I'm having a hard time getting it back down to 6.8. They take a long time to break down. I was told it might take 4-5 years to lower my pH. I'll never use them again. Go with Gypsum

4/10/2007 1:31:01 AM

Menomonie, WI (mail@gr8pumpkin.net)

Brain you answered your own question...Calcium Carbonate has a High PH, The Sulfur has a low PH. Combine the two in the form of gyspsum you have basically created a nuetral compound. Add more sulfur you get a lower PH.

4/10/2007 8:04:04 AM

western PA

Dissolving gypsum in soil results in the following reaction:
CaSO4·2H2O(water in soil)= Ca2+ + SO42- + 2H2O. It adds calcium ions (Ca2+) and sulfate ions (SO42-), but does not add or take away hydrogen ions (H+).
Therefore, it does not act as a liming or acidifying material. The Ca2+ ions simply interact with exchange sites in soil and sulfate remains dissolved in soil water.

4/10/2007 8:27:22 AM

western PA

it looks like Brians sulfer keeps accumulating. I was just wondering when too much is too much.

4/10/2007 8:28:32 AM

Eugene, OR

Thanks for that clear explanation Shannon. It's kind of like pH adjusted peat moss then I guess. I'm not sure about how much calcium pumpkin plants actually take every year but I assume it's more than the amount of sulfur they use? If you're a little(or a lot) heavy handed with the gypsum like I've been to up the Ca, will there eventually be a "surplus" of sulfur as the calcium carbonate is broken down and the Ca used by the plant which could lower the pH?

I wonder the same thing Vader. Considering what I've added to the patch over the past couple of years, the gypsum is certainly to blame for my 1500+ ppm sulfur levels. When do we cross the threshold of too much? Sorry again for piggybacking.

4/10/2007 12:03:24 PM

Eugene, OR

Some VERY interesting reading on gypsum for people like me who know squat about soil chemistry, including gypsum's effect on pH and the myth of the ideal Ca:Mg ratio. http://www.spectrumanalytic.com/support/library/rf/Gypsum.htm It seems like no matter what the topic, there's always conflicting info. The water certainly gets a little muddier anyway....

4/10/2007 12:25:50 PM

President - GPC

Brian,
I agree, the more data one searches for the more conflicting evidence one seems to accumulate. However what are we to do......lol. After spending this off season readin, readin, readin, Im a bunch more of something......lol. I now find that I really want to know what I am adding before it goes into the patch less I be trying to recorrect for years what I just did......Master says slow and sure wins the race, so now I go slow and add small amounts then retest, so I guess I did learn something...... But you are right, lots of conflicting info at times.

4/10/2007 1:55:52 PM

western PA

your not piggybackin' Brian. The more info, the better.

4/10/2007 2:19:12 PM

southwest MO

Brian, Be sure what your Sulfer is being reported as. It is probably SO4. Big difference from elemental S. Your Ca is probably reported as Total availible Ca.(which is elemental)

4/10/2007 4:55:51 PM

Eugene, OR

It's a standard A&L test....listed as S03-S. I guess that would be sulfur trioxide. Is the soil test data for sulfur a "total" sulfur number, which includes elemental S and the oxide S03?

When deciding if we need more nitrogen, we go by the number the lab gives us for NO3-N so why should sulfur be any different? Obviously, the nitrogen has to be bonded with something to keep from simply off gassing as N2 while that's not a problem with sulfur.

So, for the chemistry guys, what will the SO3 react with and what's the result of the reaction in soils? Just trying to get a handle on this so thanks for all the info.

4/10/2007 5:52:07 PM

western PA

SO3 is the anhydride of the acid H2SO4.

SO3 reacts with CaO to form CaSO4 (gypsum)
SO3 reacts with water to form H2SO4 (acid)
the addition of elemental sulfur to soil produces two hydrogen ions The hydrogen ions released cause soil pH to decrease.
Soil pH is simply a measure of the hydrogen ion concentration in soil solution, and the higher the concentration, the lower the soil pH.
Also, Upon leaching, the sodium (Na)ions will move out of the root zone as sodium sulfate (Na2SO4) soluble salt.

Just some random stuff. but I am a biologist not a chemist. i always hated chemisty.

4/11/2007 9:55:44 AM

southwest MO

The fact that they are reporting in SO3 doesnt mean that is the form the Sulfer is in when its in the soil. Its just a way to quantify S through reporting. SO4 is the form taken in by the roots so I'm a bit confused on the SO3. If Sulfer being reported as S is 1500 ppm then reporting it as SO4 would give a reading of 4500 ppm. If you dont want to be burdened by trying to figure out if they are reporting as S or SO3 or if the S and Ca were extracted and prepared the same way, just be sure to use the same folks next year and that the data is reported to you in the exact same terms. This way you will have an acurate way of looking for trends.
N03 is commonly reported as N. If you report NO3 as NO3 it would be Approx. 4.2 time higher. 100 ppm vs. 420 ppm. At any rate it is also usually repoted as extractable which can vary significantly with procedure and is different from total N-N03

4/11/2007 10:17:14 AM

western PA

SO3 is a gas, i believe.

4/11/2007 11:26:29 AM

Montoursville, PA

Geese guys I've been reading and occasionally writing parts of funny books for a long time. Few if any organic base writers use or suggest the use of gypsum. Some even say flat out don't need it..........where as a good load of manures will do much more for all of the reasons gypsum is usually applied. Yes I am aware of the reasons it is generally used. I have many years ago used gypsum but find no specific reason to use it today. In the past it was mostly because someone suggested based on what someone else did because his grandpa did.

4/11/2007 11:35:11 AM

southwest MO

Doc. I dont get the funny books thing??

4/11/2007 11:52:31 AM

western PA

YOU CANT BEAT THE MANURE !!!!!!

unfortunatly you can only put on so much, I was looking for possible alternatives to increase the calcium.

4/11/2007 1:51:38 PM