Pond silt has a couple of problems in regard to plant growth. The first is that all soil structure has been destroyed. In other words the soil has collapsed so that there are very few large pores to allow water to soak in quickly or for oxygen to penetrate deeply into the soil.
So how do we rebuild soil structure? We rebuild it by adding organic matter. Actually it is the gums and glues given off by microorganisms as they break down organic matter that gives soil better structure. If possible, add organic matter now if you wish to plant next spring. Sources of organic matter would include old rotten hay, rotted silage, leaf mold and peat moss. Add 2 inches of this material to the surface of the soil and mix it in.
The second problem with this soil is a lack of nutrients. Add a complete, balanced fertilizer to the soil and till it in before planting. Shoot for about 1 pound of actual nitrogen per 1000 square feet. For example, add 7.5 pounds of a 13-13-13 per 1000 square feet. (Ward Upham)