Your question raises a few issues. Kirby asks one of the principal ones. GAAP is one part of the issues, the other is the IRS. (gift tax)
According to GAAP, every financial transaction must be recorded in the books. Assets are to be valued at "lower of cost or market". You state that your company carried out some land transactions. Some of the assets were sold, the majority of them were donated. For the part you sold, you would debit the sales price to the receivable account, eliminate the net book value of the capitalized asset by crediting Fixed Assets and debit/or credit the difference as a capital gain profit/(loss) (other income/expense)
The part that you donated would in principle be booked the same way. If that asset still has a net book value, you would have to write off the remaining book value against capital gain/(loss) However, there is a big difference between donating that asset to a Charitable Foundation, an unrelated third party, or a company that is owned by the same shareholder. Giving it to a Charitable Foundation could give you a tax deduction depending on the net book value of the assets in your books. Transfering it to a related company would require adherence to the "lower of cost or market" rule for the "receiving company" Giving it as an outright gift, to a third party could raise a "gift tax" issue with the IRS. Rather than spending time to find the GAAP para in which "lower of cost or market" and "asset valuation" is concerned or finding the IRS Section under which the rule "a transfer of economic values between two parties must be recognized by both parties", I would "google the term "lower of cost or market" and "gift tax" and show your findings to your boss.