The problem with the ammonium sulfate is that you are dumping large quantities of nitrogen on each time. Great, if your soil is nitrogen deficient, but if not, you can "overgrow" or burn stuff. The first place to start is with a soil test. If high pH, then annual early spring and late fall applications of sulfur will modify pH without the nitrogen. Take a sample to your extension service and they will tell you what to do to modify your soil. The soil may need other additions, as well.
hortster

I live in Madison, Wisconsin, and our soil is alkaline, also. Several pH tests over the years indicate that our soil has pH = 7.6. Even so, we have a successful garden, with tomatoes, broccoli, swiss chard, brussels sprouts, green beans, & basil. We also have a raspberry patch. Our blueberry shrubs require special effort to lower soil pH, but not the garden, lawn, or raspberry patch. Much of Wisconsin was once on the floor of the ocean, and we have several layers of limestone underground that formed long ago. Since our tap water comes from groundwater that accumulates in those limestone beds, we also have hard water. I am not against using sulfur to lower soil pH, I am simply pointing out that alkaline soil can be used, as is, for growing many crops.

I agree with ericwi. You soil is alkaline but not very alkaline. The concrete pieces probably do not contribute anything to the soil pH. You should be able to grow crops in this soil with no problems. The act of growing crops will improve the soil and slowly lower the pH. Don't worry. Just enjoy the fruits of your labour.

Here is a link that might be useful: Soils and Soil Fertility

I agree with all the previous advice.

Also there is a big difference between pH 7 and 8. pH 7 is neutral. Most vegetables will grow fine until pH is around 8, then you may begin to experience iron and other micronutrient deficiencies.

I have seen numerous anecdotal reports of concrete leaching lime into soil. It sounds plausible but I think the effect is minimal. The alkalinity is probably due to your soil's natural composition unless tests show otherwise.

Make adjustments slowly if you want to lower the pH since over-correcting could be worse than doing nothing. Elemental sulfur will do the job over time, but you will need to incorporate it into the entire depth of the soil which you intend to modify, and the soil will need to remain moist and warm. You cant just flush it into the soil like ammonium sulfate or acid..

Dan

What is the level of Calcium Carbonate in your soil?
What is the ratio of Magnesium to CaCo3?
Would elemental Sulfur be a better choice for lowering that pH?
What is the level of organic matter in your soil?

"The soil in my garden is very alkaline, ph 7 to 8."

That is NOT very alkaline ... most of the state of Arizona has soil pH higher than that. I have encountered "soil" in my garden that FIZZES when you pour an acid on it! Yet, my vegetables are growing very nicely in their heavily mulched, lightly fertilized beds.

The concrete is not doing much to the pH because it's checmically locked up, the ammonium sulfate is risking over-nitrogenating.

If you feel you have to do something, spread several pounds of soil sulfur and scratch it in. It will slowly lower the pH with little risk to the plants.

What is the level of Calcium Carbonate in your soil?
What is the ratio of Magnesium to CaCo3?
Would elemental Sulfur be a better choice for lowering that pH?
What is the level of organic matter in your soil?

These questions imply that you need a soil test. For the vast majority of gardeners (99%), that is questionable expense. I have never done a soil test and never will. I add 1/2" of compost to the garden each year and fertilize depending on the crop needs. There are no problems with growing vegetables and flowers and suspect that there never will be.

The native soil pH in this area is 8.0 to 8.5. The settlers who grew wonderful wheat crops on this land did not worry about soil tests and nutrient ratios.

On the other hand, if you cannot get a bean to germinate in your soil, there may value in testing the soil to determine the problem.

Soil tests, no till practices are fine for operations dealing with 1/4 section or more of land but for a few hundred or a few thousand square feet of garden, spend your money of plants and seed.

I don't like all of the referenced article. I cringe when I see the word Gaia but nevertheless, the article is worth a read.

Here is a link that might be useful: Soil Testing for Organic Gardeners

I'm agree Eric in Wisconsin. I had my soil tested and its pH is 7.8. By using large amounts of organic material in the soil, I have been able to lower its pH and grow many crops well. I am still working on getting the blueberries to thrive but the raspberries seem to be doing ok with a spruce needle mulch.