Hey Timothy,
Do you do very many farm appraisals? No, unfortunately we do very few, and in our market (Quad Cities) we have to be very careful about the reason this land is bought. A lot of it is bought on speculation for future housing (which has now dried up). Most of the land in Scott County was bought north of Bettendorf, or PV, and that area was hot for high end homes. I actually think it is a shame to develop homes on land that will produce 220 Bu of corn and 50 Bu of beans per acre, but that is the market. The school disricts fueled the market. Scott County and surrounding counties have some of the best soils in the nation, but the housing market claimed a lot of that land up till last year. I want to talk with another Iowa appraiser who does tillable ag appraisals like me sometime. My questions are regarding what you are doing with the cost approach. I find that it is more reliable to take the overall selling price per acre divided by the CSR rating for the entire farm and then develop a cost analysis based upon selling prices per CSR point. This only works well on nearly all tillable farms. If you have a mix of pasture and tillable then I use extraction. But, some appraisers round here are still trying to value each soil type at different rates. I go with the belief that a potential buyer will pay attention to the CSR rating, Absolutely, Iowa farmers want production, why else buy the land? I don't think anyone cares about the soil type, unless they have to rotate crop. but will not be influences by whether they have a Moody or a Sac soil with nearly the same CSR rating.
For example, we just had a farm with a 62 (62...that is low for Iowa...or at least in my area) overall CSR rating sell for $6,025 per acre WOW!!. Nearly all tillable, no buildings or irrigation. That is a cost value of $97.18 per CSR point.
For the other question, I too use agridatainc.com and I think it is great. Fast service and great maps. $400 annual unlimited use.