Return to the Soil Forum | Post a Follow-Up

 o
Had soil tested, how to amend?

Posted by Farmer61 none (My Page) on
Wed, Apr 23, 14 at 21:15

I had my soil tested at the local Extension service and they said ideal was from 6.0-6.5, and mine was 6.7. I should add 1/2 a pound of sulfur per 1000 sq feet. My garden is 1460 sq feet...How can I do this? apply sulfur by the teaspoon? 1/2 pound seems a very small amount for such a large area.

Also they said it was low in Potassium, and that I should spread 20 pounds of 16-4-8 per 1000 sq feet....how can I add potassium?


Follow-Up Postings:

 o
RE: Had soil tested, how to amend?

Skip the sulfur. 6.7 is a perfectly fine pH unless you want to grow only blueberries or potatoes. The more organic matter you have in the soil, the less the pH matters (within the range of 6 to 7.5).

16-4-8: the last number represents potassium. Just look for a fertilizer that is high in the last number, such as potassium sulfate. Kelp meal is a good organic source.


 o
RE: Had soil tested, how to amend?

Your Extension Horticultural Agent, the person that made those recommendations, is simply following a chart that may or may not apply to you. The recommendation of a 16-4-8 "fertilizer" tells me that agent is more concerned about Nitrogen then either of the other two.
If the soil test indicates the levels of P and K are in the optimum, or higher levels, there is no reason to dump more of them on your soil.
What did that soil test say about organic matter?

This post was edited by kimmsr on Thu, Apr 24, 14 at 6:07


 o
RE: Had soil tested, how to amend?

I agree that 6.7 is not too terribly high. What is the calcium level? If it's not very high you might profit from a dose of gypsum.


 o
RE: Had soil tested, how to amend?

Fertilizers come in all kinds of combinations and you may not be able to find 16-4-8, but that's OK. Things to keep in mind: If your P was optimum already, just look for something with a lower middle number. Nitrogen (the first #) leaches away a lot faster than P and K so it's not as critical to have it in the same ratio. I would not use the common 29-3-3 lawn food, or 5-10-5 which has twice as much P as K. 12-12-12 is getting there, but still high on the P. You get the idea.

Compost will add nutrients as well so keep using plenty.


 o
RE: Had soil tested, how to amend?

It shows potassium being low, and last year I had problems with my bell peppers and pimento peppers. The plants looked great when I took them out of the greenhouse, but in short time they became stunted, deformed and any peppers that weren't deformed had a brown-like coating on the skin. They weren't fit to eat.


 o
RE: Had soil tested, how to amend?

Most all plants will grow best in soils with a pH in the 6.0 to 6.8 range, which is where the soil you have is and the test results tell you that no Calcium is needed and the amount of Sulfur or Gypsum is really minimal.
Potash, Potassium, K, is fairly low and that does need some attention since K does influence fruiting.
What I do not see is the amount of organic matter, which can be of importance. Perhaps these simple soils tests,
1) Soil test for organic matter. From that soil sample put enough of the rest to make a 4 inch level in a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. For example, a good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top.

2) Drainage. Dig a hole 1 foot square and 1 foot deep and fill that with water. After that water drains away refill the hole with more water and time how long it takes that to drain away. Anything less than 2 hours and your soil drains’ too quickly and needs more organic matter to slow that drainage down. Anything over 6 hours and the soil drains too slowly and needs lots of organic matter to speed it up.

3) Tilth. Take a handful of your slightly damp soil and squeeze it tightly. When the pressure is released the soil should hold together in that clump, but when poked with a finger that clump should fall apart.

4) Smell. What does your soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant odor? The more organic matter in your soil the more active the soil bacteria will be and the nicer your soil will smell.

5) Life. How many earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5, according to the Natural Resources Conservation Service, indicates a soil that is not healthy.
might be of some help.


 o
RE: Had soil tested, how to amend?

Surprising for Ca to be so high in GA, isn't it? Or maybe not, since Mag is also high. Your site must be in a field that received dolomitic lime for many years. So ph will fall slowly via precipitation.


 o
RE: Had soil tested, how to amend?

The plants looked great when I took them out of the greenhouse, but in short time they became stunted, deformed and any peppers that weren't deformed had a brown-like coating on the skin.

Sounds more like a pathogen than mineral deficiency.

See the chart ... a potassium deficiency would have dead and browning edges on the older leaves. They look like someone blow-torched the edges.

Here is a link that might be useful: MIneral Deficiency Symptoms


 o
RE: Had soil tested, how to amend?

Well, I put a little lime and wood ash on it last year and tilled it in....my garden space/house is a 100+ yr old farm, so no telling what has been done in years gone by. It was all grass when I moved here...My topsoil is only about 20 inches deep and then we start getting into that wonderful (not!) red Georgia clay. On top of that all my land is on a slope, my garden is too. The clay is closer to the surface on the top side than the bottom side...It looks as if the land was terraced years ago. I know the man I bought it from, bought it in 1960.
I have been using wheat straw as mulch the last 2 yrs and tilling it in.
So how do I add potassium to the soil? Most ferts I see in the store don't have that much....


 o
RE: Had soil tested, how to amend?

Slimy okra suggested kelp meal as a good organic choice for potassium. It has a lot of potassium. Organic amendments like kelp will stick around longer than synthetic counterparts, and there's much less chance you screw things up.

Even so, kelp has trace minerals, plant hormones that stimulate root growth, and soil conditioning substances that imporve tilth-- really subtle, powerful stuff so follow the recomended application rate for your deficiency (do not go over the reccomendation, and that applies to all amendments).

M


 o
RE: Had soil tested, how to amend?

And have a nice day, sounds like terrific soil. M


 o
RE: Had soil tested, how to amend?

The topsoil is only 6 inches in depth, not 20 inches.
Sources of Potassium are readily available depending on what you want, synthetic or natural.
Natural sources could be kelp meal (seaweed), Alfalfa meal, compost, about any vegetative waste. Natural sources of Potassium can take a while to become available to the plants, especially if the level of soil organic matter is low and there is not an active Soil Food Web to release those nutrients.


 o
RE: Had soil tested, how to amend?

"I put a little lime and wood ash on it last year and tilled it in"

That might explain the high Ca/Mag.


 o
RE: Had soil tested, how to amend?

Actually I don't think I have ever saw kelp meal in a store around here. I have seen it in some garden catalogs, but only in small quantities.... I would need enough for 1460 sq feet, any suggestions on this?


 o
RE: Had soil tested, how to amend?

If you are not opposed to using synthetic fertilizers, there are many choices.
If you are an organic gardener, compost and manure are your next-best bet. You'd need lots of it though.


 o
RE: Had soil tested, how to amend?

Well, I would like to lean toward organic eventually, but right now I am just trying to get a good crop from my garden...thanks


 o
RE: Had soil tested, how to amend?

Can you find Potassium sulfate?

That would take care of the potassium and lower the pH as well.


 o
RE: Had soil tested, how to amend?

LG, that's fine, but without determining if the amount of sulfate being applied might cause a novel imbalance (by exchanging with and flushing out other essential minerals in the soil profile), it's a shot in the dark using potassium sulfate, no? On a non-industrial scale, and not having all the prerequisite information, wouldn't you agree, that the best option for a home garden is almost always organic? M

This post was edited by Mackel-in-DFW on Sun, Apr 27, 14 at 9:47


 o
RE: Had soil tested, how to amend?

Mackel, it's easy to figure out exactly how much you are applying.

Potassium Sulfate: K2SO4
Sulfur 18.401%
Potassium 44.874%

20 pounds of 16-4-8 fertilizer is 1.6 lbs of potassium per 1,000 sq feet, or 3.5 pounds of the potassium sulfate.

Multiple by 1.46 to get the quantity for the whole area. (5 lbs of K2SO4 scattered over the whole area would do it - the difficulty would be getting an even distribution and no hot spots)

I should add 1/2 a pound of sulfur per 1000 sq feet

the 3.5 pounds of K2SO4 has .63 pounds of sulfur in it (close enough for gardens)

============
Aw heck, this is too much finicky chemistry, and if you took different samples you would probably get slightly different results from the lab.

The results aren't so far off "desirable" that it's worth the bother unless your plants start showing signs of a deficiency.

Add a layer of compost and call it done and see what happens.


 o
RE: Had soil tested, how to amend?

Hey thanks LG! I found some on ebay, here: http://www.ebay.com/itm/POTASH-5-lb-bag-SOLUTION-GRADE-0-0-50-Sulfate-of-Potash-Potassium-Sulphate-SOP-/170891226846

Free shipping, be here this week, I needed sulfur anyways and potassium.... I am just worried about the same thing happening to my peppers this year, I am sure it's from some kind of deficiency....


 o
RE: Had soil tested, how to amend?

Note, banana peels have a lot of potassium, just like the part you eat. I always compost them and there is plenty of K in my soil. :-]


 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!


Return to the Soil Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.


Learn more about in-text links on this page here