 This is the Agricultural Law and Tax Report brought to you by Purple Wave, the trusted, no-reserve equipment auction marketplace. For more information, see purplewave.com. And Rabine Law Firm. If you're in a truck accident, contact my friend David Rabine at rbr3.com. I'm Roger McCowan. When farmland is purchased, a deduction for excess soil fertility can be claimed if it can be documented. Based on an analysis of the amount and type of nutrients, the rate of depletion can be computed.