first soil test some help

mtinazJuly 20, 2009

So, I have clay soil and got my first soil test because things have not been going well. Any help would be great.

organic matter 3.1% rate M

p1 127 ppm rate vh

p2 143 ppm

k 1378 ppm rate vh

mg 405 pp

ca 2494 ppm

na 220 ppm

ph 7.7

cation exchange 20.3 meq/100g

base saturation %

k 17.4 %

mg 16.6%

ca 61.3%

na 4.7 %


180 ppm

324 lbs/a

soluble salts 2.9 mmhos/cm

Recommended 90lbs/A elemental sulfur

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"things have not been going well"

Please explain: what has been happening to the plants.

You have slightly alkaline soil, but not so alkaline that things would be dying of it.

    Bookmark   July 20, 2009 at 8:51PM
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Well the plants them selves are doing great but production is low to none exsistant. I am growing all green and no fruit.

    Bookmark   July 20, 2009 at 10:03PM
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The soil pH is a bit too high (optimal is between 6.2 and 6.8) and your level of organic matter is very low (you want between 5 and 10 percent OM) and it looks like the Phosphorus (needed for fruiting) levels are low.
How well does that soil drain?
What is the life in that soil like?
What does your soil smell like?
How well does that soil clump and also fall apart?

    Bookmark   July 21, 2009 at 8:08AM
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I think a big problem may be too much nitrogen. The first clue is "all green but no fruit" and the test supports what you're seeing. Based on the CEC, You probably need total available nitrogen somewhere in the 70 ppm range. You're at 180 ppm nitrate. That doesn't even take into account ammoniacal nitrogen. Plants don't use ammoniacal nitrogen as much as nitrate but they do us a little bit and it converts quickly to nitrate (and I guarantee there's some in there), especially in warm weather.
Phosphorus and potassium are also higher than optimum. Elevated potassium isn't much of a problem but you won't have to add any for at least a year. High phosphorus can inhibit plant uptake of the minor nutrients, most notably zinc. You won't have to add that nutrient for at least a year.
2.9 dS/m isn't too awful high and won't bother most plants and I wouldn't expect to see any problems as a direct result of salts right this minute. But it is possible that salts could reduce production and cause some tip burning of older foliage on more salt sensitive species. The more important thing that number tells us in this particular case is that you should increase your irrigations slightly to provide a small leaching fraction to avoid a build up of salts in the root zone. Infrequent deep watering is preferred over frequent shallow watering.
The ESP of 4.7 is near the upper end of the range considered low and safe. Once it starts getting up to 5 or 6, soluble sodium can start to impeded soil structure and drainage. Increasing irrigations and flushing some sodium out of the root zone will also adjust your ESP downward to a more preferred level. Just be sure to allow the soil to dry slightly between irrigations to avoid creating anaerobic soil conditions and/or an environment that favors root diseases. You don't want to over do it.
Your pH is high enough to cause some plants to show symptoms of alkalinity induced chlorosis, particularly on younger foliage. But, as stated earlier, isn't going to kill anything. Incorporating soil sulfur will adjust the soil pH downward making micronutrients more available to plants. In order to be effective, soil sulfur should be incorporated rather than broadcast. The rate of sulfur given by the lab is very conservative. It translates to about 2 lbs. of soil sulfur per 1000 sq. ft. With a pH of 7.7 and CEC of 20 I would bump that up to about 10 lbs. per 1000 sq. ft. incorporated to a 6 to 8 inch depth before your next croping cycle. The test does not mention lime content. Lime can increase the soil's ability to buffer against downward pH adjustments and an increase in lime means a higher rate of sulfur required. Without knowing the lime content 10 lbs. per 1000 sq. ft. should be pretty effective but it won't push your pH too low in this case, even if lime is absent. Soil pH changes happen slowly and only affect the soil as deeply as it is incorporated. If it isn't feasible to incorporate soil sulfur, some downward soil pH adjustment can be made very slowly over time by providing nitrogen when required with acidifying fertilizers such as sulfur coated urea with a typical guaranteed analysis somewhere around (40-0-0)and/or ammonium sulfate (21-0-0).
Like Kimmsr said, the O.M. is a little low and an increase in the organic content would improve soil physical properties. You can increase this with a top mulch of organic material that will improve the organic content of the soil as it decomposes or by tilling in organic amendment at the next cropping cycle. Just be aware that greenwaste compost, as a rule of thumb, is usually a significant source of potassium. Manure based composts are often significant sources of phosphorus and potassium. Another option is a nitrogen stable wood product such as nitrolized fir shavings, which will improve O.M.% without bumping up potassium or phosphorus significantly. If you go the top mulch route, it doesn't matter if the material is nitrogen stable or not.
For at least the next year, you can rely on a nitrogen only program. Since you have an abundance of that nutrient already, it may be a couple of months at least before you need any more. Keep an eye on the plants and only apply when symptoms of nitrogen deficiency show such as general yellowing of foliage beginning with the holder leaves. At that point, apply one of the above mentioned nitrogen only fertilizers or an organic source such as blood meal, at that manufacturer's label rate. Afterwords, nitrogen application can be based entirely on color and growth performance. Follow each fertilizer application with thorough irrigation.

    Bookmark   July 21, 2009 at 10:10AM
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I mean general yellowing of 'older' leaves.

    Bookmark   July 21, 2009 at 10:15AM
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Dan Staley

They recommended sulfur b/c the pH is high. I also see a need for P. And the OM may help the soil structure when the nutrient levels and pH gets where you need it. Bottom line: soil needs a little work and some OM added but it's a good start.


    Bookmark   July 21, 2009 at 10:17AM
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I said 2.9 dS/m and their test says "2.9 mmhos/cm"
It's exactly the same units with a conversion of 1 to 1. Decisemens per meter (dS/m) is just the newer term. (Your lab's kickin' it old school, yo).

    Bookmark   July 21, 2009 at 10:18AM
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More P ?!?!
No way, man. With a CEC of 20 you probably need about 70-80ppm.

That's probably why their P has a "vh" (aka: very high) next to it.

    Bookmark   July 21, 2009 at 10:20AM
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Dan Staley

Nah, I'm looking overall and I see the vh but with the CEC pH and N3 in there I don't think its getting used. Maybe lowering the pH will make it more moveable and that N will move out quickly enough, & depending upon crop might be needed. I'm not wedded to it one way or the other, but certainly I'd be wedded to more OM in there. And I'm envious of your 'new school results' - around here we still get fingers/elk antler or stones/cubit.


(striving daily to keep Godwin's Law out of soil discussions)

    Bookmark   July 21, 2009 at 11:15AM
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Well the plants them selves are doing great but production is low to none exsistant. I am growing all green and no fruit.

All green and no fruit is usually because the soil is relatively high on nitrogen and low on phosphorus. Or, it's overwatered. Or both. Check your watering habits.

Lowering the pH with the soil surfur would do a lot towards bringing things into balance, and tilling in some organic matter (whatever you have on hand for compost) will help.

Don't fret too much about the pH ... I'm growing stuff in alkaline desert dirt with no problems.

And don't freak out and start throwing all kinds of things at the dirt or it will get so screwed up you'll never get it straight.

    Bookmark   July 21, 2009 at 11:58AM
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I don't think its getting used.

With that CEC, pH and nitrate I'd feel perfectly comfortable with P at about 50 ppm for something like woody ornamentals (even a little lower if pH and nitrate were closer to ideal)
But since this is a situation where they're trying to boost flowers and fruiting, and I'm assuming tomatoes because they're a good bet for a common garden and I'm aiming at the heavy feeders, I would still stick with the 70-80 ppm for this situation. But hey, it's all educated guesses.
We're all on the same page with the O.M., that's for sure. I'd say about 100 stone per 400 cubits square should get that 3.1% somewhere in the 5%-6% range.

    Bookmark   July 21, 2009 at 12:05PM
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Sorry, mtinaz.
Sometimes I get caught up in cracking myself. (I am my own best audience)
My goofy rate up there would translate to somewhere in the neighborhood of 2 to 2 1/2 cubic yards of compost per 1000 sq. ft. tilled to a depth of 6 to 8 inches. (Nitrogen stable wood products would be used at the same volume but would weigh less)

    Bookmark   July 21, 2009 at 1:44PM
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newgen(9 Central California)

gargwarb mentioned "salt buildup in the rootzone". What does this look like? I may have this problem in my yard. Soil is very alkaline. Yesterday, I saw that one of my fig plant appeared weak, been that way for several days, so I gently pulled up on it (it's been inground for 1.5 years), branches has many green fruits. Since I just watered it, it was not hard to pull up on the tree, intermingled within the roots system was a bunch of white, fragile small round shells, about the size of a black pepper. These were crushed easily by finger pressure. Is that salt build up?

    Bookmark   July 21, 2009 at 5:17PM
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Thanks very much for all the replies. I have one more question. If I add compost wont that increase everything even more? I have been making a batch for a while of chicken manure with veggie scraps and straw. I also have been mulching with hay and straw.

    Bookmark   July 21, 2009 at 10:52PM
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Dan Staley

No. Compost generally has relatively low NPK. What it gives is structure, tilth, WHC, and critters/critter space that your soil needs.


    Bookmark   July 21, 2009 at 11:15PM
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Yes. Compost does generally have relatively low NPK but you have to think of it on the scale that you're using. Just for kicks I've pulled up some data.
(Shaking papers back and forth like David Letterman)
These are for samples of fully composted greenwaste (sticks, leaves, grass, etc.) and fully composted chicken manure (since you mentinoned that one). Both confirmed by solvita compost maturity testing.

Here is what you would see on the bags for guaranteed NPK analyses on a dry weight basis if these were fertilizers (with some rounding of digits)
Greenwaste compost: 1.5 - 0.2 - 0.8
Chicken manure compost: 2 - 5 - 4

Wow, that sounds like almost nothing. But keep in mind the amounts used. Below are the amounts of those nutrients that would be supplied if each material were used at the 2 1/2 cu. yd. per 1000 sq. ft. rate that I gave above.
Greenwaste compost at that rate would provide per 1000 sq. ft.

17.0 lbs. total as it decomposes
.025 lbs. immediately available nitrogen (NO3 and NH4)

3.125 lbs. total
0.58 lbs. immediately available (P2O5)

Potassium (As stated in my first post, greenwaste is a hefty source of potassium)
9.95 lbs. total
8.3 lbs. immediately available (K2O)

So, a modest rate of 2 1/2 cu. yds. per 1000 sq. ft. of this typical mature greenwaste compost would provide around 8 to 8 1/2 lbs. of immediately available potassium. That's about the same amount as supplied by 20 lbs. of potassium nitrate per 1000 sq. ft. (a ridiculous rate of application) Or, if you prefer, using the standard 2 million pounds of soil per acre furrow slice, the compost in our example would give you a boost of roughly 180 ppm immediately available K2O in the soil. (Plus what will be come available as it decomposes)
I'm going to go ahead and call that significant. That's especially true when considering the fact that the analysis originally posted shows a soil in which potassium would be sufficient for most plants at around 125 ppm to 150 ppm or so. The analysis also showed that potassium is already about ten times that.

The chicken manure compost at that rate would provide per 1000 sq. ft.

27.0 lbs. total as it decomposes
4.2 lbs. immediately available nitrogen (NO3 and NH4)

62.4 lbs. total
4.3 lbs. immediately available (P2O5)

Potassium (As stated in my first post, green waste is a hefty source of potassium)
60.6 lbs. total
43.9 lbs. immediately available (K2O)

Those numbers are downright astronomical. So, when nutrients in a compost are looked at like fertilizer percentages it can be very misleading. You have to think about real world application rates and what those numbers will actually mean when you pile on the compost. Don't get me wrong, I love compost. I actually think that the nutrients that are added, along with all of the other benefits, is one of the really cool things about compost. But the nutrient additions are, by and large, grossly under estimated.

I would try to steer clear of high phosphorus stuff especially right now if I were you. Since you've got a blend there, it's really hard to give a good guess regarding the nutrients your compost would supply. I like the hay and straw mulch though.

newgen: Doesn't sound like salts. Can you post a picture either here or in the Garden clinic forum? If you post it in the Garden Clinic forum, rhizo_1 and Jean001 will probably see it. They're pretty sharp.

    Bookmark   July 22, 2009 at 12:57PM
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Dan Staley

Now, hay and straw mulch I can get behind. The N and P amounts from a home bin, however, I cannot unless we can lessen the leaching and volatilization somehow, which the manufacturers do. Compost is needed in that soil, certainly. But if you are going to follow a recommendation for improvement, there is no control from a home compost pile and typical compost needs a large addition to make a decent difference. I did a calc around here somewhere, can't find it now...


    Bookmark   July 22, 2009 at 2:55PM
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Thanks again for all the great info. Everyone keeps telling me to add compost but I am afraid of exactly what gargwarb posted because even a yard of purchased compost could add a lot to my already crazy soil. Still not sure what I will do. Might give it a year and just keep the mulch and test next spring to see how much has been taken up by the plants ect.

    Bookmark   July 22, 2009 at 5:29PM
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Newgen -
that is not salt buildup. That is probably what's left of the time release fertilizer spheres.

    Bookmark   July 22, 2009 at 8:01PM
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I think the slow and steady approach would work great in your situation. I betcha, your plants will do pretty dang well if you just give the nitrogen level some time to drop and only apply it when necessary and not worry about P or K until you get another test that shows that you need them. Try testing again in a year and I bet you'll still be fine on both of those. O.M.% is a little low at 3.1% but over the course of a couple of years of mulching and growing like you're doing, it will improve significantly. Bump up the water a tad to avoid a build up of salts in the root zone. (but don't over do it). If you want to do something about the pH, check out my first post, but if not...7.7 isn't the end of the world unless you're growing blueberries.
Do that, and I think you'll be just fine.

    Bookmark   July 23, 2009 at 9:33AM
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newgen(9 Central California)

gargwarb, lazygardens:

Those white particles are most likely not salts after all. I even tasted one! Now I'd like to ask you guys (or anybody else) about my alkaline soil. The pH gauge needle swings all the way towards the basic side of the readout, so I know it's at least 7.x. How basic it is exactly is unknown. Do MOST fruit plants prefer acidic or basic? I just added some soil acidifier (sulfur) a couple weeks ago around each plant, still waiting for the result. How long will it take for the soil to change from basic to neutral or acidic?


    Bookmark   July 23, 2009 at 1:36PM
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taz6122(N.W. AR.6b)

You can get a PH meter really cheap at any garden center. What result are you waiting for...HELLO??

    Bookmark   August 21, 2010 at 9:24AM
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Most all plants grow best with a soil pH in the 6.2 to 6.8 range because that is where most nutrients are most available. A cheap pH meter may tell you that your soils pH is some number (I have seen too many that read the same whether the solution they are testing is a known acid or alkaline to want to spend money on one) but does not tell you why. Adding calcitic lime to a soil that has a low pH because of an imbalance of Ca and Mg will not be of much help.

    Bookmark   August 22, 2010 at 6:41AM
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