$375,000,000 Uses in Clause (l Clause

Clause (l from Amended and Restated Credit Agreement

Amendment No. 4 (this Amendment), dated as of February 2, 2007, among Terra Capital, Inc., a Delaware corporation (Terra Capital), Terra Mississippi Holdings Corp. (f/k/a Mississippi Chemical Corporation), a Mississippi corporation (TMH), and Terra Nitrogen (U.K.) Limited, a company incorporated in England and Wales (Terra UK) (Terra Capital, TMH and Terra UK each a Borrower and, collectively, the Borrowers), Terra Industries Inc., a Maryland corporation (Terra Industries), Terra Capital Holdings, Inc., a Delaware corporation (Terra Capital Holdings), the Lenders party hereto and Citicorp USA, Inc., as administrative agent and collateral agent for the Lenders and the Issuers (in such capacities, the Administrative Agent), amends certain provisions of the Amended and Restated Credit Agreement, dated as of December 21, 2004 (as amended, supplemented or otherwise modified from time to time, including previous amendments hereto, the Credit Agreement), among the Borrowers, Terra Industries,

Clause (l. in Section 8.1 of the Credit Agreement is hereby amended by (x) inserting (i) at the beginning of such clause and (y) inserting at the end thereof: and (ii) Indebtedness in respect of the Senior Unsecured Notes (2007); provided, however, that the aggregate principal amount of such Indebtedness pursuant to this clause (ii) shall (x) not exceed at any time $375,000,000 and (y) be directly applied upon issuance thereof in the refinancing, purchase, redemption, defeasance or other satisfaction of the Indebtedness described in subclause (i) of this clause (l);