Growing tomatoes in alkaline soil

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Whwoz
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Growing tomatoes in alkaline soil

#1

Post: # 54855Unread post Whwoz
Fri Oct 01, 2021 7:58 am

Last year I expanded our vegetable garden significantly, bringing a lot of soil on-site. At the time it looked good and most varieties grew well in it. A recent pH check found that it is at pH 8, which I suspect contributed to the less than average season I had with the tomatoes and Beetroot.

Just wondering if anyone here has any experience growing tomatoes and beetroot in slightly alkaline conditions and if so how the plants performed.

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PlainJane
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Re: Growing tomatoes in alkaline soil

#2

Post: # 54906Unread post PlainJane
Fri Oct 01, 2021 10:01 pm

My tomatoes, beans and other garden crops are container grown as that’s what much of Florida has; sandy, alkaline and nematode-infested soil. The orchard area got yards of bought compost added when I first cleared it, and homemade compost is laid around the fruit trees a couple times each year. So far so good in the orchard, but it will take years more before the soil is really ’good’. It’s just so very sandy.
My blueberries struggle the most as I suspected they would. I have to acidify that area periodically to keep them going. My last soil test was 4 years ago at 7.4 in the orchard area.
Another issue here is that irrigation water is also alkaline but there’s not much to be done about that.
For my tomatoes I make up a 5-1-1 mix with pine bark fines, chunky perlite and coco coir. To this I add a dry fertilizer and alfalfa pellets. Once fruiting starts I hit them with liquid Texas Tomato Food once a week. I’m pretty happy with the big fabric grow pots but I may try some deep raised beds for veggie growing at some point.
“Never try to outstubborn a cat.”
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Whwoz
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Re: Growing tomatoes in alkaline soil

#3

Post: # 54912Unread post Whwoz
Sat Oct 02, 2021 4:32 am

Thank you @PlainJane. For your irrigation water I take it you you draw directly off a mains supply without a buffer tank in-between which would allow you to acidify the water

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PlainJane
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Re: Growing tomatoes in alkaline soil

#4

Post: # 54913Unread post PlainJane
Sat Oct 02, 2021 6:02 am

Yes, @Whwoz, exactly right. On the list for ‘someday’ is a rain water collection system.
“Never try to outstubborn a cat.”
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Shule
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Re: Growing tomatoes in alkaline soil

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Post: # 54922Unread post Shule
Sat Oct 02, 2021 7:17 am

We probably have alkaline soil, since it was originally clay, and soil in the area is known to be alkaline, but our garden has never been tested. Plus, I use wood ash, so that surely raises the pH even higher. It can't be too high, though, since stuff grows. Some tomatoes have a hard time in our soil, and some do just fine. Tomatoes actually like calcium quite a bit; so, a high pH shouldn't be the end of the world if you balance it with organic matter and NPK.

My advice for alkaline soil (unless you're an organic gardener) is to do foliar fertlizer sprays so you don't have to worry about what's available in your soil so much. If you fertilize the ground, whatever you put in has to deal with the other nutrients blocking them or making them so available they're toxic. If you spray the leaves, the plant absorbs it directly.

Another thing that seems to help is mixing peat moss in the soil. The traditional thing to do is add sulfur (months in advance), but I haven't actually tried that (beyond sulfate salts).

Maintaining moisture should help, too, since that should make the nitrogen more available, which should help the plant use more calcium.

I believe the answer also depends on what's making your soil alkaline. I'm more familiar with high calcium's effects on pH than other stuff.

Adding acidic stuff should help. Some fertilizers are acidic. Peat moss is acidic. Compost is acidic. Rain has an acidifying effect.

If your water is alkaline, that could be a problem.
Location: SW Idaho, USA
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Whwoz
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Re: Growing tomatoes in alkaline soil

#6

Post: # 54969Unread post Whwoz
Sat Oct 02, 2021 2:45 pm

Shule wrote: Sat Oct 02, 2021 7:17 am
....Another thing that seems to help is mixing peat moss in the soil. The traditional thing to do is add sulfur (months in advance), but I haven't actually tried that (beyond sulfate salts).

Adding acidic stuff should help. Some fertilizers are acidic. Peat moss is acidic. Compost is acidic. Rain has an acidifying effect.

If your water is alkaline, that could be a problem.
Sulfur needs to be added as pure Sulfur, it is the conversion of sulfur to sulfate that lowers pH.

Unfortunately peat moss is practically unobtainable here Down Under, we just do not have the beds to extract it from

Have heard through other contacts that the addition of animal manure is best way to go so will be trialing that. Only seems to have affected beetroot and tomatoes, so will use the area for other crops short term.

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Paulf
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Re: Growing tomatoes in alkaline soil

#7

Post: # 54981Unread post Paulf
Sat Oct 02, 2021 6:20 pm

Sixteen years ago we moved from an area where the soil was perfect to our retirement home where the soil pH in its natural state is 8.4 to 8.7. The garden space we have had never been turned over and was made up of brush and weeds, all native so they were accustomed to the high pH. The first several years production and size of the plants, especially tomatoes and peppers was very poor compared to what we were used to. From the beginning the garden was given large amounts of compost and elemental sulphur. All this addition was directed by recommendations from a professional labs soil test. I would never use a cheap-o home test to get an accurate recommendation.

After three or three years of soil amendment the tomatoes began to prosper. We tilled under our mulching program which was newspaper base with several inches of weedless straw. The yearly soil test gave the recommended amount of sulphur and where we were as to the other soil make-up. Our soil pH dropped from mid eights down to a manageable 7.5. Production has greatly increased after about five years of taking care of the garden and its needs.

For us, compost and sulphur along with a yearly dose of nitrogen (several forms, mostly solid and chemical) has done wonders. So far as beets are concerned, they always seemed to do OK from the beginning but then maybe I just didn't pay much attention compared to the tomato crop.

mama_lor
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Re: Growing tomatoes in alkaline soil

#8

Post: # 55065Unread post mama_lor
Mon Oct 04, 2021 4:12 am

How alkaline the soil is basically has no influence on the plant, but through just one factor: nutrient availability. And all of those are micronutrients, so as long as you make sure those are taken are of, there is no problem. Of course, foliar, as Shule said, is good, but alot of work, and imo it doesn't really work as well as advertised.

So first thing is to identify if you do have micronutrient problems. Zinc, Iron, Manganese, this is the deadly trio of alkalinity. I put Zinc first, because it is probably the one that would limit crop the most and also not so easy to fix.
Iron is easy to identify and also fix: just buy some eddha, apply from time to time with watering and that's it.
Zinc will limit you through the leaf size, huge factor, since big leaves mean lots of photosynthesis. Small leaves, some interveinal chlorosis, short internodes, these are the classic symptoms of zinc deficiency, and the effect will usually appear in waves, and then a recovery. For example, early season, lots of new small fruit, suddenly the Zinc requirements go up, the plant makes small leaves up top, cholorsis appears. When that first batch is now grown, not necessarily ripe yet, there will be a recovery, leaves are sizing up again, you can clearly see how the new leaves are bigger than the intermediate ones. This is classic zinc. Very very common, much more than people realize (in any soil).
Manganese is more tricky, if you have the other two you also can just assume you have this one as well.

But there is an easy cheating fix, as long as pH is not too extreme. Humic acids. Just make sure you have new organic matter added every autumn and mixed in to a depth of at least 10cm, in the form of manure, compost, etc, and the chelating effect of these will pretty much solve your problems and make these elements available to the plant. Also add some sulfur at that time every year, even if it's just the top layer of the soil with good pH, it should be enough to help the micronutrient requirements of the plant.

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