These are factors that limit productivity on a local, rather than a broad, basis. Examples of physical factors include flooding, salinity, sand, and gravel pockets. They are expressed in terms of a percentage of potential production. There can be a maximum of three miscellaneous factor deductions per soil area. In this sample profile, no physical factor deductions have been applied. Examples of physical factor deductions that might be applied are: PSA - the symbol for poor drainage and salinity, and SD which is the symbol for sand.
For example, if five percent of the area of 85 acres had salinity reducing the crop yield to nothing, the deduction is applied by multiplying the master rating by 0.95. This is the same as subtracting 5% from the master rating.
Similarly on this sample profile, if there were a SD 90 discount, the potential productivity would be reduced by ten percent for the presence of pockets of sand found throughout the cultivated soil area. For instance: the sand reducing crop yields over the affected area by 25% could affect 40% of the area of the field. 40% x 25% = 10% reduction.