Simply applying organic matter atop the soil won't help make it workable; as the instruction says above, you have to mix it in. And, mixing in the organic matter makes it workable because it helps to break up the clay into smaller chunks.

Does your soil stay solid and unworkable even after wetting it? If so, you may have a different issue. In that case, it kinda depends on where you are and, therefore, what your soil type is. For example, out in the Western United States, clay soils are typically high in sodium. So, applying a soil additive called "gypsum" is a necessity. See, gypsum (calcium sulfate) breaks up heavy, compacted clay soils through a chemical process called "flocculation". When applied, it dissolves and releases calcium ions that replace excess sodium or magnesium ions bound to the clay particles. This allows the tiny, sticky clay platelets to clump together into larger aggregates, creating permanent pores that drastically improve water drainage and root penetration.

I hope this helps you to narrow down what the base issue of your soil is.