I've heard of adding sulfur to the soil to acidify--are there any ill effects of doing so? I've also heard of adding coffee grounds, but I don't drink coffee. (I've also also heard that pine needles--which are abundant here--are acidic; if I used them as a mulch, would that effectively lower the pH, or is that not a good idea?)

Thanks!

By the way, brassicas and legumes prefer it around 7.
My soil pH is 8.3, high enough to warrant the use of sulfur.

I also regularly use oak leaf mold and a great deal of homemade compost (that includes pine straw) throughout the season. But my goal is always just to get it down to the area of 7 and try to hold it there +/- a tad.

Pine straw, compost, and leaf mold will always return to the neutral pH as they decompose over the season so while great soil amendments they will also have a short term acidifying benefit if regularly applied.

Dave

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You've got it: Pine needle mulch can perform a double duty. For coffee ground go to a Starbucks. Leaf mold is another. Generally most organic matter are on the acid side. PLUS most garden veggies can grow fine in pH near 7. Though slightly acidic (6.8) is almost near ideal. Most herbs prefer 7++.

Will pine straw help? Probably but it will take a while. Likewise, sulfur takes a while to acidify the soil. My soil tends towards alkaline (around 7) and I have had some wonderful tomatoes and some dull tomatoes which I suspect had to do more with amount of water and variety than the soil.

We do keep liquid ironite in the garage and if plants are showing signs that they are having trouble, we use it but we wait for the signs of iron chlorosis but we rarely have that problem with vegetables, even with our alkaline, very hard water that we irrigate with.

Dave

Results were evident by the time I tested again a couple of months after application that first year. The second year I applied less and by the third year, I refrained from adding any at all. Last season was the fourth year and we applied at the same rate we did the second year. As far as lowering pH, it's working fine. It just feels rather strange to be adding heavy metals to my soil.

Iron (ferrous) sulfate oxidizes quickly to ferric sulfate after application. This reacts with calcium carbonate in the soil to form calcium sulfate and ferric carbonate, which then decomposes to ferric oxide. Ferric iron is unavailable to plants and also insoluble at a pH above 7. The potential for iron toxicity starts to develop if the pH is shifted below 6.0, especially if also compounded by flooding, since this enables the reduction of ferric iron back to plant-available ferrous iron.

If it makes you feel any better, clay is naturally high in aluminum. Like the iron, it is completely locked up in neutral or alkaline soil.

We must have excellent buffering qualities (hope I'm using that term correctly), though, because the efforts to lower pH here seem to be sticking better than areas such as daninthedirt is speaking of (great username, by the way, Dan). I also have a rather easy time lowering water pH for our aquarium fish; half distilled and half dechlorinated tap water keeps it in a comfortable range for them without having to purchase adjusting chemicals. (We're now on the river water pipeline that goes into town; well water was much, much worse and I could only use a small amount mixed with the distilled.)

We're rural in the Humboldt area, but we have family who is mixed farming the Young/Allan area. :) Prairie Garden Seeds is in Humboldt here and I met Jim and his family briefly when I picked up a seed order last year. Nice folks. I should ask for a tour of the seed gardens someday.

One more question. Our garden has flooded before. How long does it take for the iron to then get back to an unavailable state after such an incident?

So as not to hijack crabbygardener's thread any further (sorry about that), I'm going to spin off with a new post over in the soil forum regarding my question about zinc and copper.