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Garden Problems and Soil Test Confusion

Posted by atinius Tennessee (My Page) on
Sat, Aug 2, 14 at 14:56

Hi there! Our summer garden took a drastic turn for the worst mid season. Our seeds all came up, and transplants survived but everything was severely stunted. Our tomatoes were the only thing that produced and even those were very limited. Most of our plants just quit growing at a certain point and produced little to nothing (5 squash plants = 1 tiny little squash). We got a soil test before planting anything for the fall/winter but now my head is swimming with the results. I've scoured through this forum and the internet which pretty much resulted in a lot of calculating/excel sheet madness/confusion. I thought I'd post up the results and see what you all with more experience could recommend.

*Everything is in Pounds Per Acre
pH 7.3
Phosphorus 387
Potassium 746
Calcium 8539
Magnesium 616
Zinc 11.8
Iron 14
Manganese 93
Boron 3.5
Sodium Na 170

ANY guidance or advice is welcome!


Follow-Up Postings:

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RE: Garden Problems and Soil Test Confusion

your ph is too high at 7.3. I suggest lots of home made compost with starbucks coffee grounds. Grounds are acid and will lower the ph or you could try some other soil acidifiers like sulfur, you can look them up. I am sure others will suggest them to you. Its so bad, I would try to dig the ground straight into the soil in your case.
Avoid Super phosphate, bloom food, lime, eggs shell or anything else that raises your ph. I would also avoid manure fertilizers. You want only things that lower your ph like vinegar, and peat moss as soil additives.

This post was edited by tropical_thought on Sun, Aug 3, 14 at 0:24


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RE: Garden Problems and Soil Test Confusion

pH of 7.3 isn't too high for the majority of garden plants but it is definitely pushing it. At 7.3 many of the minerals start to be effectively locked up; it clobbers mineralization in other words. That can make many of your mineral readings effectively worthless since they aren't so readily available to the plants.

You also can't easily lower pH if there is much of what they call "free calcium" in the soil. That's Ca that's ready and willing to react with acidic materials, and the big problem with that sort of Ca is it tends to exert a strong control on pH until it is entirely used up, and that can mean a long hard slog with "acidic" treatments.

So, like they said, avoid any additives with Ca and use anything you can that's even remotely acidic. Manures can be on the acid side of things but tend towards the alkaline as they age. Coffee grounds are mildly acidic, they come reported as low as 6.2 and as high as 7.0, but some say that they also tend to buffer the pH. Compost will often buffer the pH, but the reported pH of composts is also all over the map.

It may take years, but you can often lower pH. Check your additives carefully, and be glad you're not driven to grow blueberries.


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RE: Garden Problems and Soil Test Confusion

Don't worry about the pH! My vegetables do just fine in the far more alkaline desert dirt. Add compost.

What did the soil lab say was high or low, and what did they recommend?

Was your weather much different this year?
Did you apply any amendments?

Soil deficiency and overdose problems seldom develop in a period of weeks - if things were OK last year and bad this year ... look to some change in weather or in something you applied.


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RE: Garden Problems and Soil Test Confusion

Optimal soil pH levels for most plants is in the 6.2 to 6.8 range so while 7.3 is above neutral it is not "too" high, my soil settled at 7.2 many years ago. Coffee grounds, Oak leaves, Pine needles, etc. will not have a significant affect on soil pH, although adequate levels of organic matter may well help stabilize that. A soil pH of 7.3 is at the high end of when most all plant nutrients are most readily available.
Missing from that soil test report is that amount of organic matter in the soil. Adequate levels of organic matter in Tennessee clay will help in many ways.
Is this the first soil test you have had done? If so this is a comparison of the norm for Tennessee. Over time the soil tests will show the results of what you have done with that soil.
Did the test report include graphs showing below optimum, optimum, or above optimum nutrient levels? If that soil test was done by your University of Tennessee your county horticultural agent should be available to answer questions.


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RE: Garden Problems and Soil Test Confusion

Thanks for the suggestions everyone! Everything was deemed "sufficient" except for phosphorus and Potassium which were deemed "Very High". This is new soil that was bought from a nursery and only amended slightly with compost. I think my roommates put some fish fertilizer in it as well. The soil seems to be extremely sandy and I noticed that even after watering it dries out really quickly so I'm sure that has something to do with it too. Going to try adding in some compost and sulfur before adding some fall crops and say a prayer. I know peat moss can be controversial...any thoughts on adding that in too?


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RE: Garden Problems and Soil Test Confusion

7.3 does not seem high, but the difference bt. 7.3 and 7.2 is big in fact. It is hard to lower ph, even just a little bit. If you water supply is also alkaline. Mine is so I am constantly batting with lower the ph, lots of trips to Starbucks for grounds. They are free, if you ask for them.

Peat moss is over priced, and you would have to buy a lot of it, so if you don't mind spend a lot of money or money is no object, then go ahead. It is somewhat renewable, by the way, I don't use it anymore because coffee grounds are free and I make compost, and I don't really need to use it.

Lots of house plant potting soils use peat moss and they use it a lot indoor gardening situations like ferns in a green house. It is cheaper if you are just using it for a few potted plants, but if you want to buy a lot of it for a garden, that is really going to add up. The price of peat moss has doubled or tripled in the last few years. I like bagged woody products, myself, but some people really like peat moss and don't mind paying the price.


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RE: Garden Problems and Soil Test Confusion

If there is no other source of organic matter peat moss could be an option, but it is a non renewable resource that requires large amounts of other non renewable resources to harvest it and the harvesting destroys wild life habitat in the process.
If that soil drains too quickly that may be the problem since plants cannot uptake needed nutrients in the absence of soil moisture.
Perhaps these charts that show nutrient availability at various soil pHs might be of some use.

Here is a link that might be useful: nutrient availability charts


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RE: Garden Problems and Soil Test Confusion

Lack of blooming or fruiting is often caused by insufficient P, but in your case it's very high. Are the leaves yellow? You may have nitrogen deficiency, for example if the soil had some partly finished compost that had a lot of wood chips or sawdust in it - like manure/bedding.

It may just be a watering problem too. Do you have anything you can use for mulch? Grass clippings (if you don't spray herbicides on the lawn), or wood chips (free from many utility tree trimming services).

Next time you get a soil test, ask for organic matter analysis.

Calcium does not react with acids, it's completely neutral. Perhaps grubby is referring to carbonate/bicarbonate, which may go along with calcium (i.e. lime is calcium carbonate). Calcium itself has no effect on pH.

Any organic acids you add, like vinegar, will be only temporary and will biodegrade. Sulfur (powder, dug in when you plant), ferrous sulfate (usually a liquid that you dilute and pour on), or aluminum sulfate are more permanent. Still I wouldn't worry too much about the pH, if you add compost each year it shouldn't be a big issue at 7.3.


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RE: Garden Problems and Soil Test Confusion

  • Posted by glib 5.5 (My Page) on
    Mon, Aug 4, 14 at 14:45

nooooo! 7.3 is too high! that means that my 7.6 garden is a complete product of my imagination. I could not have grown anything really. all that work for nothing...


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RE: Garden Problems and Soil Test Confusion

  • Posted by nil13 z21 L.A., CA (Mt. Wa (My Page) on
    Mon, Aug 4, 14 at 17:05

heheh glib. My 7.3 soil didn't grow 8 foot high tomatoes with 7.4 water either. lol

New soil bought from a nursery and amended with compost? Did you mix it into the native soil at all? We need pictures of what you are doing and where you are growing. It sounds to me like you are growing in mostly organic matter from bagged nursery 'garden soil' and are having a hard time actually wetting it and that is the source of the problems. If the stuff is brand new and the PK levels are that high, I am guessing the N levels are pretty damn high too.

we need pics of the soil and if you have pics of the plants as they failed that would be great too.


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RE: Garden Problems and Soil Test Confusion

  • Posted by glib 5.5 (My Page) on
    Mon, Aug 4, 14 at 17:15

sure, but why take tomatoes (an acid soil vegetable) as the sole example? I used to have 8ft tall toms in 5.5 soil, but here brassicas, betas, parsnips are so much better. squash is better, garlic and onions are better, and beans about the same. I can grow good cardoon and very large radicchio.


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RE: Garden Problems and Soil Test Confusion

  • Posted by nil13 z21 L.A., CA (Mt. Wa (My Page) on
    Mon, Aug 4, 14 at 20:57

Sorry i forgot the little eyeroll emoji c.c at the end of that. I was agreeing with you. My tomatoes were actually 8 ft tall and full of fruit. Hell i have had some on 10 foot cages grow all the way up and back down in that "pH is far too high soil".

We really need a snark font,


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RE: Garden Problems and Soil Test Confusion

  • Posted by glib 5.5 (My Page) on
    Mon, Aug 4, 14 at 22:03

interesting. since I moved here, great crops but my toms top out at 5 ft. why? the soil is great (20% OM), but truth be told, here I do not have full sun (back then I had full sun all day, not a tree within 100 ft). Can not discount sunlight but it is difficult to rule out pH.

This winter I am going to turn all beds with beans, squash, allium and tomatoes into hugelkulturs and see if that pushes me over the hedge. It is mostly for the tomatoes, I am already getting fist size garlic, but I am hoping also for earlier squash and beans crops. After all, as soon as a seedling connects the mycelium, it extends its root reach down a few feet. Surely hugel mitigates pH effects, because the roots get enveloped by the fungi and their direct contact with the soil is greatly reduced.


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RE: Garden Problems and Soil Test Confusion

Sunlight should not be discounted as a possible cause. I moved my beds 50 ft. where they would get more sun, and it's literally like night and day, especially with the tomatoes. They were leggy and weak and now they're deep green with thick stems and loaded with tomatoes. I had tree root problems too, but sunlight was a big part of it.


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