COLUMBUS PINE AND AMORY HARDWOOD ROUNDWOOD SUPPLY AGREEMENT

Exhibit 10.21

COLUMBUS PINE AND AMORY HARDWOOD ROUNDWOOD SUPPLY AGREEMENT

PINE AND HARDWOOD ROUNDWOOD SUPPLY AGREEMENT (this “Agreement”) made this 5th day of March 2007 between WEYERHAEUSER COMPANY, a Washington corporation (hereinafter referred to as “Weyerhaeuser”), and DOMTAR PAPER COMPANY, LLC, a Delaware limited liability company (hereinafter referred to as “Domtar”).

RECITALS

AGREEMENT

NOW, THEREFORE, in consideration of the mutual covenants and agreements hereafter contained, Domtar and Weyerhaeuser agree herein as follows:

1.1 This Agreement shall be effective as of April 1, 2007 (the “Effective Date”) and shall remain in effect until March 31, 2008 (the “Initial Term”).

1.2 Weyerhaeuser agrees to sell and Domtar agrees to buy Pine and Hardwood Roundwood under this Agreement for an additional term of Four (4) years (the “Second Term”), which shall commence upon expiration of the Initial Term. Weyerhaeuser and Domtar agree to notify the other party at least Twelve (12) months prior to the expiration of the Second Term if either party wishes to not renew this Agreement. The terms set forth under Section 2, Quantities, and Section 7.1, Price, Payment and Price Determination, will be reviewed and agreed to annually by both parties during the Second Term. For each successive year during the Second Term, quantities will be adjusted to reflect available Weyerhaeuser harvests and the price will be adjusted to reflect the then current fair market value. By June 30 of each calendar year during the Second Term,

Weyerhaeuser will provide Domtar with a rolling estimate of the available quantities for the next three (3) years. Any dispute, issue, or controversy arising pursuant to this Section 1.2 shall be handled by the Dispute Resolution process outlined in Section 9.1 of this Agreement.

1.3 This Agreement shall terminate automatically upon:

Subject to Section 8, Weyerhaeuser agrees to sell, and Domtar agrees to purchase such quantities of Pine and Hardwood Roundwood which Domtar requires, delivered at the times required, for its coated groundwood paper mill which Domtar owns at Columbus, Mississippi and for its hardwood chip plant which Domtar owns at Amory, Mississippi (the “Mills”). Weyerhaeuser shall supply to Domtar on an annual basis approximately 64,000 tons of Pine Roundwood, from its Timberlands operations during the Initial Term. The parties will meet quarterly, beginning in June, 2007, to discuss the volume of Hardwood Roundwood Weyerhaeuser will supply to Domtar each quarter. The parties have agreed that the volume of Hardwood Roundwood for the first quarter of the Initial Term shall be approximately 14,000 tons.

3.1 Pine and Hardwood Roundwood sold hereunder shall be of a quality which is satisfactory for use in the Mills of the type being operated by Domtar and shall meet the roundwood log specifications set forth in Exhibit “A”.

3.2 Payment will be made in accordance with Exhibit “B” and only for the actual quantity of Pine and Hardwood Roundwood that meet the specifications set forth in Exhibit “A”. No payment will be made for Pine and Hardwood Roundwood which, for any reason, fail to meet these specifications.

3.3 Domtar shall make statistically valid measurements and tests as it, in its absolute discretion, deems necessary to determine the quantity and quality of Pine and Hardwood

Page 2 of 8

Roundwood supplied by Weyerhaeuser. Domtar shall communicate the results of the measurements and tests in a timely manner. Weyerhaeuser shall accept and be bound by such measurements and tests, and the results thereof, subject always to Weyerhaeuser’s right to verify said measurements, tests and results upon reasonable prior notice and during regular business hours. Any correction required to be made by a party to an amount paid for a particular shipment of Pine and Hardwood Roundwood as a result of this Section 3.3 shall not, in any case, be made to an amount paid for a shipment of Pine and Hardwood Roundwood delivered more than 90 days prior to such measurement and testing.

3.4 In the event that an individual trailer load or partial trailer load of Pine and Hardwood Roundwood fails to conform to the specifications set forth in Exhibit “A”, Domtar shall have the right to refuse acceptance of any such trailer load or partial load upon delivery at scales. Domtar shall have the right to refuse further deliveries of Pine and Hardwood Roundwood until such time Domtar is satisfied that satisfactory steps have been taken by Weyerhaeuser to rectify the cause of the failure to meet the Pine and Hardwood Roundwood specifications set forth in Exhibit “A”.

All Pine and Hardwood Roundwood delivered hereunder shall be weighed by Domtar. Weighing and basis for payment for truck delivered Pine and Hardwood Roundwood shall be by ton weight. A ton is 2,000 pounds. Subject to Section 3.3, Weyerhaeuser agrees to be bound by Domtar’s weigh scale.

5.1 All Pine and Hardwood Roundwood shall be delivered by Weyerhaeuser in approximately equal monthly instalments and as near as possible at uniform daily rates, subject to alternative delivery schedules as Domtar and Weyerhaeuser may from time to time agree upon in writing so as to accommodate, where possible, the other party’s production schedules, and subject, where possible, to any plant or logging shutdowns incurred by either party. Delivery shall take place at the Mills’ weight station or at an alternative location designated by Domtar. The parties will endeavour to agree on any changes, for example price and volume, to reflect such proposed changes to the delivery location. Should the parties fail to agree upon any changes, either party may, by written notice, request that the matter be determined in accordance with the procedures for dispute resolution set forth in Section 9 of this Agreement.

5.2 Weyerhaeuser and Domtar agree to mutually explore techniques and methods to improve truck turn around time to benchmark levels. Weyerhaeuser and Domtar representatives will meet at least once each quarter to review progress toward this goal, establish action steps/deadlines and assign responsibility.

Page 3 of 8

All Pine and Hardwood Roundwood to be supplied by Weyerhaeuser under this Agreement shall be supplied free and clear of any and all prior claims, security interests, mortgages, liens, charges or any other encumbrances whatsoever. Title to, all rights of property in, and all risks of loss or damage or destruction to the Pine and Hardwood Roundwood shall pass to Domtar upon delivery to the Mills’ truck weight station or at an alternative location designated by Domtar.

7.1 The price per ton for Pine Roundwood for the Initial Term is set forth in Exhibit “B”. Prices are paid on an adjusted quarterly basis to reflect expected conditions encountered during the Initial Term. The price per ton for Hardwood Roundwood for the first quarter of the Initial Term is set forth in Exhibit “B”. The price per ton thereafter during the Initial Term shall be determined by the parties on a quarterly basis, beginning in June, 2007, at the same time the parties negotiate the next quarter’s volume of Hardwood Roundwood.

7.2 All prices are exclusive of sales and any other taxes applicable to the sale of Pine and Hardwood Roundwood under this Agreement.

7.3 Domtar shall pay for Pine and Hardwood Roundwood delivered as specified hereunder within fifteen (15) days from the last day of the week in which deliveries were made.

7.4 Each party shall maintain detailed records of: (i) all measurements and tests made by it pursuant to this Agreement; and (ii) all costs incurred by it for which it is, pursuant to this Agreement, entitled to be reimbursed in whole or in part by the other party. Each party shall make such records available to the other party for inspection at all reasonable times at the expense of the party making the request for an inspection.

The duties of either party hereunder shall be excused to the extent and for the period of time necessitated by the occurrence of any fire, flood, earthquake, other natural disaster, labor dispute, war, direct act or intervention of any government or subdivision thereof, or other event of force majeure beyond the control of any party. The affected party invoking this provision shall promptly notify the other party in writing of the nature and estimated duration of the suspension period, and shall exercise all reasonable diligence in curing such condition, except in cases where such suspension is of a permanent nature and such condition is not curable as a result. The party unable to obtain performance by reason of force majeure shall be free to deal with third parties, provided it acts in a manner not inconsistent with its obligations under this Agreement.

9.1 Any issue, dispute or controversy arising pursuant to this Agreement (a “Dispute”) shall be settled in the following manner. Upon written request of either party, the representatives of Domtar and of Weyerhaeuser shall promptly confer and exert their commercially reasonable efforts without the necessity of any formal proceeding related thereto

Page 4 of 8

to reach a reasonable and equitable resolution of such Dispute. If such representatives are unable to resolve such Dispute within ten (10) business days, the Dispute shall be referred to the responsible senior management of each party for resolution. Neither party shall seek any other means of resolving any Dispute arising in connection with this Agreement until both parties’ responsible senior management have had at least five (5) business days to resolve the Dispute following its referral to them.

9.2 If the Dispute cannot be resolved by senior management, then the Dispute shall be submitted to binding arbitration. If arbitration is required, the arbitration proceedings shall be administered by the American Arbitration Association (the “AAA”) or such other administrator as the parties shall mutually agree, and conducted in accordance with the AAA Commercial Arbitration Rules. Judgment upon any award rendered in arbitration may be entered in any court having competent jurisdiction. The arbitration shall be conducted at a location in the State of Mississippi selected by the AAA or other administrator.

10.1 Weyerhaeuser warrants to Domtar that Weyerhaeuser has good, clear and unencumbered title to the Pine and Hardwood Roundwood sold hereunder and has the full lawful right to sell said Pine and Hardwood Roundwood. Weyerhaeuser further warrants that each delivery of Pine and Hardwood Roundwood shall meet the specifications contained in Exhibit “A”. Weyerhaeuser’s obligation under this warranty is limited to the replacement of the defective portion of the shipment with Pine and Hardwood Roundwood that meet the specifications set forth in Exhibit “A”. THIS WARRANTY IS EXPRESSLY IN LIEU OF ALL OTHER WARRANTIES EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY, AND ALL OTHER OBLIGATIONS OR LIABILITIES ARISING OUT OF WEYEHAEUSER’S FAILURE TO MEET SAID SPECIFICATIONS, INCLUDING LIABILITIES ARISING FROM CLAIMS OF CONTRACT OR TORT.

10.2 Each party agrees to indemnify and hold harmless the other party from and against all claims, liabilities and expense (including reasonable attorney’s fees) arising out of the manufacture, sale, purchase and use of the Pine and Hardwood Roundwood which are proximately caused by the negligence or wilful misconduct of the indemnifying party.

10.3 In no event will either party be liable to the other for any special, incidental or consequential damages (including, without limiting the generality of the foregoing, or punitive damages), regardless of whether the party knows or should have known of the possibility of such damages being incurred by the aggrieved party.

No attempted assignment of this Agreement, whole or in part, by operation of law or otherwise, shall have any force or effect whatsoever without the prior written consent of the other party. In the event of the sale or other form of transfer of all or substantially all of the assets composing Weyerhaeuser’s Timberlands, such sale or transfer shall not be completed by Weyerhaeuser unless

Page 5 of 8

this Agreement is assigned by Weyerhaeuser to any purchaser(s) of all or substantially all of Weyerhaeuser’s Timberlands and such purchaser(s) undertakes in writing to Domtar to be bound by each of the terms hereof as if it was an original party to this Agreement. In the event that such measures are complied with, Weyerhaeuser shall be released from any ongoing obligations hereunder as to the portion sold as and from the date of sale or transfer of such assets. In the event of the sale or other form of transfer of all or substantially all of the assets composing the Mill, such sale or transfer shall not be completed by Domtar unless this Agreement is assigned by Domtar to the purchaser of the Mill and such purchaser undertakes in writing to Weyerhaeuser to be bound by each of the terms hereof as if it was an original party to this Agreement. In the event that such measures are complied with, Domtar shall be released from any ongoing obligations hereunder as and from the date of transfer of such assets.

Any notice, consent, approval, authorization, waiver or permission hereunder shall be ineffective unless in writing, signed by a representative of the sender authorized to do so by an officer of the sender, and shall be deemed given only when delivered in person to an officer of the addressee or when transmitted by facsimile (provided confirmation is sent by mail within 1 business day) or upon receipt when such notice was sent by mail. The term “sent by mail” shall mean deposited in the mail, registered or certified mail return receipt requested, postage prepaid, addressed to the receiving party at the address and to the attention of the person below or such other address or person as the receiving party may notify the other:

The laws of the State of Mississippi shall govern all aspects of this Agreement, including its validity, interpretation, performance, operation and enforcement. It is the intent of the parties that this Agreement be the binding and enforceable obligation of each party and be interpreted as aforesaid from and after the date of execution hereof.

Weyerhaeuser agrees to comply with all applicable federal, state, and local laws, rules, and regulations, including, but not limited to, the Fair Labor Standards Act, Social Security Act, Occupational Safety and Health Act, unemployment compensation laws, Worker’s Compensation

Page 6 of 8

laws, Department of Transportation regulations, and Weyerhaeuser specifically agrees to indemnify and hold Domtar harmless from any claims, liabilities or expenses arising out of the violation of any such laws, rules and regulations by Weyerhaeuser its officers, agents, employees and/or contractors.

Weyerhaeuser shall assure that each subcontractor shall agree with Weyerhaeuser to be bound to Weyerhaeuser by the terms of this Agreement relevant to the portion of the work to be performed by such subcontractor and to assume toward Weyerhaeuser such obligations and responsibilities that will insure that no arrangement or agreement with any subcontractor is inconsistent with this Agreement or adversely affects Domtar’s exercise of its rights hereunder. Weyerhaeuser agrees that it is fully responsible to Domtar for the acts and omissions of its subcontractors and of persons directly or indirectly employed by them. Nothing contained herein shall create any contractual relations between Domtar and any subcontractor or alter such subcontractor’s status as an independent contractor.

During the performance of this Agreement, Weyerhaeuser shall maintain and keep in force, at its own expense, the following insurance coverage’s and minimum limits:

All such policies of insurance shall provide the same shall not be cancelled nor the coverage modified nor the limits changed without first giving thirty (30) days prior written notice thereof to Domtar. No such cancellation, modification or change shall affect Weyerhaeuser’s obligation to maintain the insurance coverages required by this Agreement. Except for Workers’ Compensation Insurance, Domtar shall be named as an Additional Insured on all such required policies. All liability insurance policies shall be written on an “occurrence” policy form and by insurance companies acceptable to Domtar. Weyerhaeuser shall be responsible for payment of any and all deductibles from insured claims under its policies. The coverage afforded under any insurance policy obtained by Weyerhaeuser pursuant to this Section 16 shall be primary coverage regardless of whether or not Domtar has similar coverage. Weyerhaeuser shall not perform any work under this Agreement unless and until evidence of such insurance, including renewals thereof, has been delivered to and approved by Domtar. The minimum limits of coverage required by this Agreement may be satisfied by a combination of primary and excess or umbrella insurance policies. The maintenance of this insurance shall not in any way operate to limit the liability of Weyerhaeuser to Domtar under this Agreement.

Page 7 of 8

This Agreement supersedes all prior agreements and communications and shall not be altered by either party except by consent of both parties in writing executed by their duly authorized representatives.

IN WITNESS WHEREOF, the parties have executed this Agreement as of the date first above mentioned.

Page 8 of 8