 The deduction is often claimed over three years, with most of it occurring in the first year. A common approach is to deduct 60% in year one, 30% in year two, and 10% in year three. Don't depreciate the excess amount. It's a depletion deduction. There's no IRS form for depletion, so just add the deduction to the fertilizer line and separately track it. This has been the Agricultural Law and Tax Report. I'm Roger McCullough.