Kelp is also a good source of K.

A pH of 7.5 is well within the tolerated range of peas, kale, beets and other veggies in these families, and a little above the range of solanums and cucurbits. To accomplish a more gentle lowering of pH, I'd continue using the alfalfa pellets and SBM (both of which will gradually acidify the soil over time) and add sulfur at the low end of recommended amounts, particularly if your soil is sandy. I use Tiger Sulphur, which is 90% S and 10% clay and the pellets "explode" once exposed to moisture and warmth. Till it well into the soil.

For more quick results and less risk of getting your pH too low, use iron sulfate instead. You should be able to purchase that at a garden store. Iron sulfate heptahydrate has one-sixth the acidifying power of sulfur, but don't apply more than 4 lbs per 100 sq ft at any one time. Till it in.

Great advice and right in keeping with my love of using alfalfa and SBM. You're making this adjustment sound easy

In regard to the iron sulfate, did you mean 4 lbs per 1,000 ?

Nope, 4 lbs per 100, or 40 lbs per 1000 sq ft. In my clay loam with high OM content, this gives me a pH drop of about 0.3 points, but it could be a drop of 0.5 to 0.7 points in a lighter, sandier soil.
If you do use this much, irrigate well after tilling and let it sit for a week before planting anything. A better approach, though, would be to apply 2 lbs per 100 sq ft and 2 lbs again later in the season between crops. Don't apply to an existing crop or it could burn them.

If you are not planning to grow potatoes, watermelons, tomatoes or peppers, I would even avoid the iron sulfate and just continue using organic N fertilizers to adjust the pH.

This post was edited by Slimy_Okra on Fri, Apr 11, 14 at 13:08

Most of the research I have seen, and my own experience, tells me that vegetative waste in soil does not, at least in the short term, significantly affect soil pH. Alfalfa needs an alkaline soil to grow well in, pH above 7.0.
I even added peat moss to a planting bed with a soil pH of 5.7 to lower that so I could grow some blueberries and the next soil test showed the soil pH was 7.2. The pH of tree leaves is in the 3.2 to 3.8 range and the pH of peat moss is in the 4.5 range so if, as my experience indicates, adding tree leaves or peat moss to my soils changes the pH from 5.7 to 7.2 why would I expect any other vegetative waste to do anything else? One professor of soil science I talked with did suggest that organic matter might lower a soils pH over time, like eons, but short term organic matter will raise a soils pH.

High-nitrogen organic amendments (or ammonium-based nitrogen fertilizers) do lower soil pH, albeit in small increments. The process of conversion of proteins to urea, then to ammonia, and finally to nitrate, lowers the pH.