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Soil ph levels

Posted by pommes 6 (My Page) on
Wed, Mar 3, 10 at 15:20

Hello. Question: Is a soil ph of 5.5 to acidic for most veggies (besides potatoes)? I understand that the IDEAL level for most veggies is 6.5-7 ph but I read also that each vegetable can handle slightly different ranges. Each site I read gives them different ph tolerances so it's hard to get any objectivity.

I have a bunch of organic seeds (cabbage, shallot, tomatoes, beans,radishes, carrots) but I just got a ph testing of my soil on March 1st (I know:stupid).
Any hope or should I just throw the seeds away....
or is it still worth the effort to go ahead and try the seeds I got?

I put Lime on March 2nd (along with lots of compost) in the ground but I suppose it won't change the ph for a good few months to a year.

Follow-Up Postings:

RE: Soil ph levels

I'm not sure what you are looking at but there's a big difference between "ideal" and "preferred" pH ranges. Most plants have a rather broad "preferred" range and for most veggies, that is from 5.5 to 7.5. The "tolerated" range is even broader. I see nothing wrong with your current pH as it is and I'd go ahead and plant.

Vegetables Ideal pH
Artichoke 6.5 – 7.5
Asparagus 6.0 – 8.0
Beans 6.1 – 7.5
Beet Root 6.0 – 7.5
Broccoli 6.0 – 7.0
Brussel Sprouts 6.0 – 7.5
Cabbage 6.0 – 7.5
Carrot 5.5 – 7.0
Cauliflower 5.5 – 7.5
Celery 6.0 – 7.0
Chicory 5.0 – 6.5
Corn 5.5 – 7.0
Cress 6.0 – 7.0
Cucumber 5.5 – 7.5
Garlic 5.5 – 7.5
Horseradish 6.0 – 7.0
Kale 6.0 – 7.5
Kohlrabi 6.0 – 7.5
Leek 6.0 – 8.0
Lentil 5.5 – 7.0
Lettuce 6.1 – 7.0
Mushroom 6.5 – 7.5
Mustard 6.0 – 7.5
Onion 6.0 – 7.0
Parsnip 5.5 – 7.5
Pea 6.0 – 7.5
Peanut 5.0 – 6.5
Pepper 5.5 – 7.0
Potato 4.5 – 6.0
Pumpkin 5.5 – 7.5
Radish 6.0 – 7.0
Rhubarb 5.5 – 7.0
Sweet Potato 5.5 – 6.0
Shallot 5.5 – 7.0
Soybean 5.5 – 6.5
Spinach 6.0 – 7.5
Tomato 5.5 – 7.5
Turnip 5.5 – 7.0
Water Cress 5.0 – 8.0
Watermelon 5.5 – 6.5

RE: Soil ph levels

  • Posted by ericwi Dane County WI (My Page) on
    Thu, Mar 4, 10 at 1:29

Here in Madison, Wisconsin, our soil has a pH around 7.6, and we can grow most vegetables with no problem. Limestone is plentiful around here, and our tap water comes from deep wells that must terminate in limestone formations underground, because the water has considerable lime content. If your soil has a pH around 5.5, there must be a reason. Is there a possibility that volcanic ash settled in your area, to considerable depth, at some point in the last 10,000 years?

RE: Soil ph levels

Hi ericwi. Our property is in a forested pine, shady area, therefore the higher acid content, at least I think. We live on the outskirts of Vienna,Austria called the 'Wiener woods'. The whole area is known for it's questionable soil quality. When I started working on our new property the neighbors always told me, 'you can't grow much around here.'

But, I think many garden soils tend to lean towards the more acidy/sauer side, especially in more wetter, cooler regions.

Last question: I sprinkled a little organic Lime (required amount per m2) on the soil on March 1st after I got a 5.5 reading. Will that really have much effect on the PH by the time it's time to plant a lot of the veggies (April/May) or will it only kick in after 6 months to a year?

RE: Soil ph levels

Most all soil nutrients are most readily available to plants with a soil pH in the 6.2 to 6.8 range which is why many people try to get their soil in that range. The graph in the article linked below will show that, kind of more or less.

Here is a link that might be useful: Soil pH and nutrient availability

RE: Soil ph levels

I recently became much more aware of the role of fungi in soil chemistry. You likely have a 'fungal soil' type, which tends to be acidic. Improving the bacterial component of the soil will help raise the pH.

Below is a link describing fungal techniques in crop production. Thank Borderbarb for the link.

I would get a compost pile started, or seek out other sources of compost/manures to help promote bacterial activity in the upper part of the soil. I would also recommend that you not disturb the soil more than necessary. Fungal soils are a good thing.

Here is a link that might be useful: Build on-farm inoculum production system

RE: Soil ph levels

hi and thanks for all the comments.
kimmsr, thanks for that great chart. I just hope now still that I don't have a disaster on my hands if I can't get the soil much above 5.5pH this season. I soo much want to go ahead and plant something.

Any answers as to how long organic lime takes to really affect soil pH? I hear some say a little change could take place within a couple of months, but full effect in 6 months to a year? Any thoughts, experiences with this?

I am also giving the soil a lot of mature compost.

RE: Soil ph levels

It can take years for lime to modify a soil pH. I wonder if bone meal would be a good alternative, one that also provides some nutrients (Nitrogen, Phosphorus, Calcium).

Since you are adding compost, you can assume that you are adding 'buffer' capacity to the soil. Buffering allows chemical exchange despite less than optimum pH levels. I think this is also referred to as CEC - Cation Exchange Capacity.

RE: Soil ph levels

thanks idahog. I don't know if we have bonemeal here. interesting. I'll check.
I thought the compost would help the soil in that respect.

I read from the above chart,if its accurate that a few common veggies can still do ok around a pH of 5.5.

I'm hoping they're pretty correct.

RE: Soil ph levels

  • Posted by ericwi Dane County WI (My Page) on
    Thu, Mar 4, 10 at 19:39

Have you considered growing blueberries? They thrive in acidic soil, pH between 4.5 and 6.5, but they do need full sun to be productive.

RE: Soil ph levels

While it does take a while for lime to bring a low soil pH up it does not take years, if you put the right amount and the right kind of lime (calcitic or dolomitic) into that soil. Large amounts of organic matter in the soil can also help buffer a soil pH out of the range most nutrients are most readily available.

RE: Soil ph levels

I think you are making too much of nothing :-) Soils in my area are by nature acidic. A pH of 5.5 to 6.5 is pretty much to be expected, depending on location. Very few bother to do much in the way of adjusting pH except to lime for lawns, which do not thrive under acidic conditions. But with regards to ornamental and edible plantings, that range accommodates the largest number of plants and so pH is seldom attempted to be altered. This is also a rather intensively agricultural area with many organic farms, small truck farms and wholesale plant growers.

RE: Soil ph levels

Thanks gardengal48. I like that answer. I think I'm making to much of nothing. I'll do the little things possible for a fun garden season. It's my first so it's experimental anyways. I'm supposed to learn as I go and be unexpectedly surprised if I get a few good results. thanks

RE: Soil ph levels

The soil pH is less of a concern in soils with adequate levels of organic matter. If your soil has sufficient levels of OM it can be more acidic or more alkalin with fewer problems seen as a result.

RE: Soil ph levels

Fascinating thread. I just had my veggie garden soil tested, and the pH is 7.4. Definitely on the alkalin side. Should I acidify my garden a bit, or just stick to the veggies that will do well at this level (thank you, gardengal)?
Or does it matter, given that I will be adding some organic matter--homemade compost and composted manure. I also have a cover crop of legumes to be tilled in before planting.
Thank you!

RE: Soil ph levels

If you add sufficient quantities of organic matter over time that will buffer your high soil pH. Adding something to lower that high pH, usually sulfur, will take several months not a few days to see much results or about the same time frame as adding organic matter. Get the level of OM in your soil up to the optimal 5 to 8 percent and any plants growing there should not be too adversly affected.

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