Adding iron sulfate to my strawberry bed
I tested the ph of my strawberry bed and it's very alkaline at about 7.5. The worker at the garden center I shopped at recommended iron sulfate. Is this safe to use on a strawberry bed, since I intend to eat the fruit? If it's ok to use, how soon after I apply it can I plant my bare root strawberries? If it's not safe to use, what is recommended to acidify a strawberry bed?
Arapahoe County Colorado
Your question is more complicated than one might expect, so please bare with me for this lengthy response.
To answer your question directly, iron sulfate (sometime known as ferrous sulfate) can be used to change the ph of your soil. I have not found anything in the research to say exactly how long it takes to change the ph of your soil. It won't be immediate because the chemical reactions take place over time. In some cases, over a year. http://www.cmg.colostate.edu/Gardennotes/222.pdf
It is true that strawberries will grow best in soils between 5.8 and 6.5, but people grow strawberries all the time in our alkaline soil. A ph of 7.5 is on the border of being too alkaline.
For growing strawberries in our soils, what matters most is a well drained soil with organic matter. It might be best to amend your soil with fertilizer and organic matter rather than try to change the ph.
Finally, how accurate do you think your soil test was? CSU offers soil tests for $35. And if you tell them you intend to plant strawberries in this patch of your garden, they will tell you specifically how to amend it. http://www.soiltestinglab.colostate.edu/
Sorry for the long answer. I hope this helps.