Residue decay is influenced by the chemical and physical characteristics of the crop residue, and the chemical and physical characteristics of the soil. Crop residues decay faster when tilled into the soil than if left standing undisturbed. The major requirement for crop residue decay is an active microbial population in contact with the residue.
Decomposition is slow during the winter when it is cold.
Similarly a wet rainy summer would have greater decomposition than a cool dry summer. Decomposition is drastically reduced in soils that become saturated with water. Oxygen is required for maximum microbial activity. The development of peat bogs in the upper Midwest shows how long term saturation with water slows plant residue decomposition. The chemical and physical characteristics of a crop residue will affect how fast a residue will decompose.