In this subchapter:
(1) “Category of the land” means the value classification of land for timber production, based on soil type, soil capability, general topography, weather, location, and other pertinent factors, as determined by competent governmental sources.
(2) “Net to land” means the average net income that would have been earned by a category of land over the preceding five years by a person using ordinary prudence in the management of the land and the timber produced on the land. The net income for each year is determined by multiplying the land’s potential average annual growth, expressed in tons, by the stumpage value, expressed in price per ton, of large pine sawtimber, small pine sawtimber, pine pulpwood, hardwood sawtimber, hardwood pulpwood, and any other significant timber product, taking into consideration the three forest types and the four different soil types, as determined by using information for the East Texas timber-growing region as a whole from the U.S. Forest Service, the Natural Resources Conservation Service of the United States Department of Agriculture, the Texas Forest Service, and colleges and universities within this state, and by subtracting from the product reasonable management costs and other reasonable expenses directly attributable to the production of the timber that a prudent manager of the land and timber, seeking to maximize return, would incur in the management of the land and timber. Stumpage prices shall be determined by using information collected for all types of timber sales, including cutting contract and gatewood sales.