Vegetable Gardening Soil, Compost & Mulch

Desperately alkaline soil -- what to do?

5 years ago

I've started a vegetable garden and fruit trees in previously uncultivated land in extremely high and dry desert. This country does not have nurseries, soil testing agencies, and supplies like you have in the US and UK, etc.

The soil seems to be very alkaline -- it sizzles and bubbles when I poured vinegar on it. The construction process left a lot of cement mixed into the ground of the garden: not cured solid pieces of concrete, but small chunks crumbling between my fingertips. So far I've had good success with asparagus (known to be tolerant of alkaline soil), winter squash (with plenty of manure mixed in), peas, turnips and beets. Tomatoes, lettuce and other greens, and several other things have stayed alive but been very disappointing. Brassicas get nasty hairy cabbage worms but seem to be doing okay in terms of the soil.

Tomatoes are one of my highest priorities because the commercially available tomatoes in this country have tended more and more to the rock-hard tasteless type over recent years.

Commercial compost is not available, and given the economy of this place, the organic materials I can get are: autumn leaves (in season), cow manure (very very dried out), and sawdust. Wood chips are definitely not available. I have been known to go and cut weeds along the river before they go to seed, and bring them home in my car as mulch. Oh -- and when there are not pandemic lockdowns, I recently started collecting used coffee grounds from a couple of cafes, and I have high hopes about that when things loosen up again.

I bought some sulfur granules online, but they are awfully expensive considering that my 1500 sq foot garden if it's pH 8 or higher -- is this right??? -- should require tens of kg.

So far my approach has been to just try to incorporate as much cow manure into the soil as I can, mulch where the bed or base of the plant can be protected from wind, mix tiny amounts of sulfur into the soil, and just keep hoping.

Here's vinegar fizzing on the soil last summer.

Can you help me with any advice or tips?

Featured Answer

JoJo (Nevada 9A)

5 years ago

last modified: 5 years ago

My soil pH is over 8.5, pretty much as high as it gets. As others have said -- DON'T FIGHT IT. It's a losing battle. Instead, work in all your available organic matter. It may take a couple of years but be patient. It's not going to happen overnight. Don't forget to dig in you plant-based kitchen scrap.

Be generous with water. You have lots of salts (minerals) accumulated in the top layer, so the water will help to move them deeper and out of the rootzone.

I grow chard, lettuce, etc. during the cool months, and then switch to tomatoes, peppers, eggplant when it warms up. Tomatoes are by far the hardest to grow in the high desert. They need a windbreak, a light shade cloth, deep mulch, constant watering (including showers to increase humidity around the plants), and protection on cold nights.

This is an excellent resource from a pro who also travels around the world to consult on issues related to desert horticulture:

https://xtremehorticulture.blogspot.com/

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Comments (7)

daninthedirt (USDA 9a, HZ9, CentTX, Sunset z30, Cfa)
5 years ago
last modified: 5 years ago
You should do a simple pH test to know where you stand. pH paper is readily available and inexpensive. Fizzing vinegar is likely indicating carbonates, which may or may not indicate serious alkalinity. Now, to the extent that your problem is really seriously alkaline soil, you need to check your irrigation water as well. Ground water from alkaline soil is going to be pretty alkaline as well. If your water is seriously alkaline, soil treatments aren't going to work very well. My soil is pH 7.9 (as set by mineral buffering), but my tap water is pH 9.2. I don't have any hope of acidifying my soil very much as long as I'm irrigating with that tap water.
cindy-6b/7a VA
5 years ago
Here's an article from Iowa State that has a number of suggestions. Not sure how many of these products are available where you are though. One that I use that isn't included in the article is Holly Tone by Espoma.

https://hortnews.extension.iastate.edu/1994/4-6-1994/ph.html#:~:text=If%20your%20soil%20is%20alkaline,acidifying%20nitrogen%2C%20and%20organic%20mulches.
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HighColdDesert
Original Author
5 years ago
Thank you! Good suggestions.

Some times of year I can only irrigate with ground water, but from June or July the small canal near me usually starts running and I could get some mountain runoff water from that. The previous summers I've been too lazy to do it, but I think your point is good, and I should take the trouble to use it when I can.
toxcrusadr
5 years ago
last modified: 5 years ago
Your soil is probably derived from limestone (old seabed) and because the climate is dry, it has not leached away. You will not really be able to change the soil pH very much. Instead, concentrate on increasing the organic matter content with compost and manure. This will help compensate for the naturally high pH. I have relatives in New Mexico where the pH is over 8, and they grow fine vegetable gardens. The compost will help neutralize some of it over time, but mainly, the compost helps just making nutrients available due to all the ion exchange sites, regardless of pH.

Besides, if you calculated what it would take in acidifiers to neutralize all that soil (which weighs a ton or more per cubic yard), it would be an insane amount. So don't try to fight it. Outsmart it with compost.
armoured
5 years ago
Yep, compost compost compost. With own household scraps and other things that can be composted (eg cardboard, some paper), may be able to get something close to enough, if never close to how much you might want.
daninthedirt (USDA 9a, HZ9, CentTX, Sunset z30, Cfa)
5 years ago
As noted already, you may well not have "desperately" alkaline soil. It's likely alkaline, but the desperation is presumed. Fizz does not imply desperation. Do a real pH test. Once you're able to do that, you can assess acidification with some confidence.