Organic matter is one of the primary constituents of soil that really is good for any kind of soil. It doesn't make any difference whether you have clay or you have sand. It will do something good for you. It makes the nutrients available, holds moisture, reduces erosion, also it actually it decomposes in the soil to produce nutrients that are available in the soil by acting with the soil and reducing the ph of the soil. Organic matter is an ideal to take a high ph soil a little more toward the acid side. Of course on the other hand to that you want to add something to increase the ph of the soil to get around to something like a ph of 6 or in that area. Most the time lime is used for that. So depending on how you look at lime, organic matter may not be able to increase ph of the soil but on the other hand you can definitely decrease the ph of the soil by say an eight down to a six by using organic matter.