When I took my Master Gardener training in RI, I was too embarrassed to admit I added wood mulch to my soil to loosen it up - till the instructors offered that that was what they did. No details on which woods were better or worse - I used mostly pine in NY and in NM I can only get cedar - it's just a matter of what I can get in the home centers. Soil is quite alkaline here, and no adverse reactions to the cedar.

I have two raised beds that I'm thinking of, with log borders and separated by a little walkway. One has a tree at the far end of it. My thought was to put a dwarf apple tree in one and blueberries and raspberries in the other. But I can separate out the blueberries and raspberries, no problem. Now I'm wondering if the tree will interfere and if I could plant my dwarf apple tree there somewhere. Perhaps -- big tree (already there) -- raspberries -- walkway -- dwarf apple tree (or some dwarf fruit tree) -- blueberries. But then I'm worried that the acidic soil that I require for the blueberries might bother the fruit tree. Thanks for the comments. I didn't realize the raspberries and blueberries aren't the best of neighbors. My yard's an odd shape, and I have a pointed area in back of some trees that right now just has weeds and suckers in it. It gets partial sun. I cleared some of the weeds out and planted a raspberry bush there. My thought is that the raspberries could take over as much as they wanted. But the raspberry rapidly died. :-( I also planted a blueberry bush next to the house where it gets morning sun and mixed some sulfur into the soil. The blueberry bush is alive but looks rather peaked.

I will answer the questions that were asked of me, above. The sulfur that goes into the bottom of the "V" shaped hole is not mixed in with the dirt because I want it to be assimilated slowly, over a period of years. The only purpose of this application of sulfur is to counteract the tendency of the surrounding alkaline soil to raise the pH of my blueberry shrub. I don't know how effective this method is, I have never tried to prove that it accomplishes what I expect. The typical hole dimensions are 24 inches diameter by 16 inches deep. The reason for putting down sulfur in a ring, on the surface, is essentially historical and idiosyncratic. When I started growing blueberries, back around 1993, I did not have a local source of sulfur, so I was using white vinegar, 5% acidity, mixed with our local tap water, to lower soil pH. This method works, but the vinegar disappears in about a month, so you have to keep repeating the application over the growing season. It is not a practical method for lowering soil pH. When I finally picked up a pH meter, and found a local source of agricultural sulfur in 50 lb bags, I had maybe 16 blueberry shrubs already well established, and I did not want to dig them up, apply sulfur, and replant. So, I applied sulfur to the surface, and that is how I have been doing it ever since.

Here's my take on the agricultural sulphur/ferrous sulphate and iron chelate. Agricultural or elemental sulphur will provide more acidifying power per pound of material applied, however the soil microbes have to convert it from the sulphur form to oxides of sulphur, which can then act to acidify the soil. It takes time for the acidification to work and it will occur over a period of time, you have to get the sulphur into the ground for the microbes to attack, and the effect will be a bit longer acting. The larger the sulphur particles you spread, the slower the process. Elemental sulphur is relatively cheap so is often used agriculturally. We generally use sulphur strictly as a fertilizer to replace what the crops are removing from the soil, being leached away, or tied up into mineralized compounds, plus it is relatively low volume. As a fertilizer, we often apply it at 30 lbs/acre. Another option is to use gypsum, calcium sulphate, which is commonly used to treat highly alkaline/saline soils as it is quite cheap, acidifying, and provides additional calcium. (In moister climates where soils are more acidic, they do the opposite, applying lime -- calcium carbonate-- to raise the pH). When applying gypsum, we would apply it on the order of 1000-2000 lbs/acre or more. With ferrous sulphate, you have moved up a step in cost but you are providing sulphate ions (or is it anions?) that will provide the acidifying effect, and because it is already converted to a soluble and ionic form, it will work quite quickly. At the same time, you are providing free iron that the plants can take up and the acidifying effect of the sulphate slows the process of tying the iron up in the soil. Many soils, particularly in alkaline areas, have plenty of iron, but it is tied up in the soil and unavailable to plants, and that is the situation here. We have a lot of red soils, the red coming from oxidized iron (rust). There is no deficiency of iron but it is mineralized and unavailable. Combine that with a pH of around 8 or higher and there are a lot of plants that will die of iron deficiency. Conifers, golden willows (lost a row of them in the cemetery to that, and nearly lost the spruce trees), petunias, raspberries, and even kentucky blue grass where the lawn is only sprinkler irrigated, for example. With iron chelate, you have a form of iron that is more available to plants, however it is relatively much more expensive. The chelate can be absorbed into the leaves if used as a foliar spray, though too strong a solution will burn. Because it can be pretty well directly absorbed by the plants, it can have an almost immediate effect on new growth. I've seen it recommended to water the ground with the iron chelate, but I think it tends to get tied up in the alkaline soil fairly quickly (I think the chelate breaks down fairly quickly, then the high pH ties up the iron again, and you need large quantities which become quite expensive. I had always had recommendations from the extension service to use iron chelate for iron deficiency, but later I was advised to use the ferrous sulphate by a professor for the combined free iron/acidifying properties. When I used the iron chelate, I never had much in the way of results unless I sprayed weekly at least, and that just doesn't happen with me. With the ferrous sulphate, I could spread it once and see lasting effects for anywhere from the remainder of the summer to several years. Part of my lawn is watered with a sprinkler using well water which is very high in lime. Gradually it turns yellow and thin with iron chlorosis. Fertilizing with nitrogen had no effect. Add some ferrous sulphate and in a week it was turning green, growing like it was badly overfertilized, and the stand thickens up. One year my supplier stopped carrying the ferrous sulphate but had ferrous gluconate and said it was much easier to use and worked the same--so I wondered but tried it. Think I still have most of the bag. It showed no effect on the plants, smelled like molasses and had no irritating dust so I found a new supplier for the ferrous sulphate (I'm not going to apply it if I don't get results). I don't fully remember my chemistry from school, acids/bases, oxidizers/reducers, strong vs. weak acids & bases & the chemical reactions that take place when these chemicals are placed in solution and I'm sure there are those out there that can more than adequately cover the subject (not that I'd want to learn it all over again, though!) I mainly try to cover some of the principles and describe what has worked from experience. Plus, I've never tried to grow blueberries as trying to provide an acid environment in my soil seems like too high a maintenance. Overall, what is being dealt with here is that in drier climates, the soils tend to have a large reservoir of lime and an alkaline pH. Acid loving plants may not need acid to live, however they consume quantities of minerals which are mineralized and unavailable at high pH, but become readily available at lower pH and blueberries have adapted to soils where these minerals are readily available. Trying to lower the pH of the soil to create an acid one suitable for blueberries is very hard, because to make the soil acid you have to essentially eliminate the alkaline lime in the soil, and it will take tons of amendments to do that. To compensate, you remove the soil, replace it with organic matter which is naturally acidic, then work to counteract the ongoing process of your climate and geology from turning the new acidic, organic soil back into an alkaline, mineralized soil and add a few of the more important nutrients the plants need so that they are readily available, even if the pH is a little higher than the plant desires. One last caveat--in acidic soils, NEVER add ferrous sulphate for an iron deficiency. You don't need more acid (unless you actually want a more acidic soil). Use iron chelate or the ferrous gluconate. Sorry this is much too long, but hopefully it explains the basis of my thoughts so you can judge for yourselves what is best in your situation.