The stone rating is based on a discount for annual stone removal and the wear and tear on farm equipment that includes the rating assigned and the point discount. In the example the stone rating is S2. This is an annual stone removal of 0.1 to 0.15 cubic yards per acre, or approximately 16-24 rock-picker loads of stone per year, per quarter.
This stone-rating category is one of several economic factors that add to the cost of production and are expressed as point deductions. The economic factors account for costs that are inherent to farmers in farming the land.
* Although there is an N/A classification in the manual, it is not applied as the land is classified as too stony for arable agriculture. Such lands should be rated as pasture or hay lands if there is greater than 2.00 cubic yards of annual removal per acre.