Sandy and loamy soils naturally remain open and workable and sustain
good tilth with surprisingly small amounts of organic matter. Two or
three hundred pounds (dry weight) of compost per thousand square
feet per year will keep coarse-textured soils in wonderful physical
condition. This small amount of humus is also sufficient to
encourage the development of a lush soil ecology that creates the
natural health of plants.

Silty soils, especially ones with more clay content, tend to become
compacted and when low in humus will crust over and puddle when it
rains hard. These may need a little more compost, perhaps in the
range of three to five hundred pounds per thousand square feet per
year.

Clay soils on the other hand are heavy and airless, easily
compacted, hard to work, and hard to keep workable. The mechanical
properties of clay soils greatly benefit from additions of organic
matter several times larger than what soils composed of larger
particles need. Given adequate organic matter, even a heavy clay can
be made to behave somewhat like a rich loam does.

Perhaps you've noticed that I've still avoided answering the
question, "how good is your compost?" First, lets take a look at
laboratory analyses of various kinds of compost, connect that to
what they were made from and that to the kind of growing results one
might get from them. I apologize that despite considerable research
I was unable to discover more detailed breakdowns from more
composting activities. But the data I do have is sufficient to
appreciate the range of possibilities.