<PAGE>

                                                                    Exhibit 10.3

--------------------------------------------------------------------------------
DEBTOR NAME AND ADDRESS    LENDER NAME AND ADDRESS        LOAN DESCRIPTION

TEXAS TIMBERJACK, INC.     FIRST BANK & TRUST EAST TEXAS  Number 0453740
6004 US HWY 59 SOUTH       2510 W. FRANK                  ----------------------
LUFKIN, TX 75901           P.O. BOX 151510                Amount $5,000,000.00
                           LUFKIN, TX 75915               ----------------------
                                                          Date 04-12-2002
                                                          ----------------------

[_] If checked, refer to the attached addendum incorporated herein for
    additional Debtors and their signatures.
--------------------------------------------------------------------------------

                         COMMERCIAL SECURITY AGREEMENT
--------------------------------------------------------------------------------
This Commercial Security Agreement (Security Agreement) is an Addendum to a
Commercial Loan Agreement, dated 04-12-2002. (Loan Agreement) between TEXAS
                                -----------                           -----
TIMBERJACK, INC. (Borrower) and Lender. This Security Agreement is further
----------------

governed by the terms of the Loan Agreement, where applicable. References in
this Addendum to terms defined in the Loan Agreement shall have the definitions
given to them in the Loan Agreement, unless otherwise indicated. Debtor and
Borrower may be the same. Where Borrower and Debtor are not the same. Debtor
means the owner of the Property subject to this Security Agreement and Borrower
means the obligor on the Loan Agreement.

SECURED DEBTS. This Security Agreement will secure the following debts (Secured
Debts), together with all extensions, renewals, refinancings, modifications and
replacements of the Secured Debts:

     (1) Sums Advanced. All sums advanced and expenses incurred by Lender under
         the terms of the Loan Agreement or this Security Agreement.

     (2) Specific Debts. Debts created by the following instruments or
         agreements (include items such as borrowers' names, note amounts,
         interest rates, maturity dates, etc.):



     [_] (3) All Debts. All present and future debts from Borrower to Lender,
             even if this Security Agreement is not specifically referenced, or
             if the future debt is unrelated to or of a different type than this
             debt. If more than one person signs the Loan Agreement as Borrower,
             Debtor agrees that this Security Agreement will secure debts
             incurred by any Borrower either individually or with others who may
             not sign the Loan Agreement. Nothing in this Security Agreement
             constitutes a commitment to make additional or future loans or
             advances. Any such commitment must be in writing pursuant to the
             terms of the Loan Agreement.

SECURITY INTEREST. To secure the payment and performance of the Secured Debts,
Debtor gives Lender a security interest in all of the Property described in this
Security Agreement that Debtor owns or has sufficient rights in which to
transfer an interest, now or in the future, wherever the Property is or will be
located, and all proceeds and products of the Property "Property" includes all
parts, accessories, repairs, replacements, improvements, and accessions to the
Property; any original evidence of title or ownership; and all obligations that
support the payment or performance of the Property; "Proceeds" includes anything
acquired upon the sale, lease, license, exchange, or other disposition of the
Property; any rights and claims arising from the Property; and any collections
and distributions on account of the Property. This Security Agreement remains in
effect until terminated in writing, even if the Secured Debts are paid and
Lender is no longer obligated to advance funds to Debtor or Borrower.

PROPERTY DESCRIPTION. The Property is described as follows:

[_]  Accounts and Other Rights to Payment: All rights to payment, whether or not
     earned by performance, including, but not limited to, payment for property
     or services sold, leased, rented, licensed, or assigned. This includes any
     rights and interests (including all liens) which Debtor may have by law or
     agreement against any account debtor or obligor of Debtor.

[_]  Inventory: All inventory held for ultimate sale or lease; or which has been
     or will be supplied under contracts of service, or which are raw materials,
     work in process, or materials used or consumed in Debtor's business.

[_]  Equipment: All equipment including, but not limited to, machinery,
     vehicles, furniture, fixtures, manufacturing equipment, farm machinery and
     equipment, shop equipment, office and record keeping equipment, parts, and
     tools. The Property includes any equipment described in a list or schedule
     Debtor gives to Lender, but such a list is not necessary to create a valid
     security interest in all of Debtor's equipment.

[_]  Instruments and Chattel Paper: All instruments, including negotiable
     instruments and promissory notes and other writings or records that
     evidence the right to payment of monetary obligation, and tangible and
     electric chattel paper.

[_]  General Intangibles: All general intangibles including, but not limited to,
     tax refunds, patents and applications for patents, copyrights, trademarks,
     trade secrets, goodwill, trade names, customer lists, permits and
     franchises, payment intangibles, computer programs and all supporting
     information provided in connection with a transaction relating to computer
     programs, and the right to use Debtor's name.

[_]  Documents: All documents of title including but not limited to, bills of
     lading, dock warrants and receipts, and warehouse receipts.

[_]  Farm Products and Supplies: All farm products including, but not limited
     to, all poultry and livestock and their young, along with their produce,
     products, and replacements; all crops, annual and perennial, and all
     products of the crops; and all feed, seed, fertilizer, medicines, and other
     supplies used or produced in Debtor's farming operations.

[_]  Government Payments and Programs: All payments, accounts, general
     intangibles, and benefits including, but not limited to, payments in kind,
     deficiency payments, letters of entitlement, warehouse receipts, storage
     payments, emergency assistance and diversion payments, production
     flexibility contracts, and conservation reserve payments under any
     preexisting, current, or future federal or state government program.

[_]  Investment Property: All investment property including, but not limited to,
     certificated securities, uncertificated securities, securities
     entitlements, securities accounts, commodity contracts, commodity accounts
     and financial assets.

[_]  Deposit Accounts: All deposit accounts including: but not limited to,
     demand, time, savings, passbook, and similar accounts.

[X]  Specific Property Description: The Property includes, but is not limited
     by, the following (if required, provide real estate description):

     SUBJECT TO ADDITIONAL TERMS AND COVENTS CONTAINED IN THE ATTACHED
     AGREEMENT.

[X]  USE OF PROPERTY. The Property will be used for [_] personal [X] business
     [_] agricultural [_] __________________ purposes.

[_]  ADDITIONAL TERMS: (include additional Security Agreement terms and
     contracts requirements).

Debtor Type: [_] Individual [_] Partnership [X] Corporation
             [_] ___________________ State of Registration (if applicable)  TX
                                                                          ------
--------------------------------------------------------------------------------
SIGNATURES. By Signing. Debtor agrees to the terms contained in this Security
Agreement and acknowledges receipt of a copy of this Security Agreement.

DEBTOR:                                LENDER:
TEXAS TIMBERJACK, INC.                 FIRST BANK & TRUST EAST TEXAS

/s/ Illegible Signature                /s/ B. E. FRANKS
                                       ------------------------------------
                                       B. E. FRANKS, JR.
                                       VICE PRESIDENT

--------------------------------------------------------------------------------
COMMERCIAL SECURITY AGREEMENT: to be used with Form COMM-AGREE
NOT TO BE USED FOR LOANS SUBJECT TO CONSUMER LENDING LAWS

                                                                   (page 1 of 2)

<PAGE>

GENERALLY. This Security Agreement is governed by the terms of the Loan
Agreement and the laws of the state in which Lender is located. In the event of
a dispute, the exclusive forum, venue, and place of jurisdiction will be the
state in which Lender is located, unless otherwise required by law. Each
Debtor's obligations under this Security Agreement are independent of the
obligations of any other Debtor. Lender may sue each Debtor individually or
together with any other Debtor. Lender may release any part of the Property and
Debtor will remain obligated under this Security Agreement for the remaining
Property. The duties and benefits of this Security Agreement will bind and
benefit the successors and assigns of Debtor and Lender. No modification of this
Security Agreement is effective unless made in writing and signed by Debtor and
Lender. If any provision of this Security Agreement is unenforceable, then the
unenforceable provision will be severed and the remaining provisions will still
be enforceable. Whenever used, the plural includes the singular and the singular
includes the plural. Section headings are for convenience only and should not be
used to define or interpret the terms of this Security Agreement. Time is of the
essence.

NAME AND LOCATION. Debtor's name indicated on page 1 is Debtor's exact legal
name. If Debtor is an individual, Debtor's address is Debtor's principal
residence. If Debtor is not an individual, Debtor's address is the location of
Debtor's chief executive offices or sole place of business. If Debtor is an
entity organized and registered under state law, Debtor has provided Debtor's
state of registration on page 1. Debtor will provide verification and
registration and location upon Lender's request. Debtor will provide Lender with
at least 30 days notice prior to any change in Debtor's name, address, or state
of organization or registration.

WARRANTIES AND REPRESENTATIONS. Debtor owns the Property or, to the extent that
this is a purchase money loan, will purchase the Property with the proceeds of
the loan. The Property is free and clear of all liens, security interests,
encumbrances, and other adverse claims and interests, except those to Lender or
to which Lender consents in writing.

DUTIES TOWARD PROPERTY.

Protection of Lender's Interest. Debtor will defend the Property against any
other claim. Debtor agrees to do whatever Lender requires to protect Lender's
security interest and keep Lender's claim in the Property ahead of the claims of
other creditors. Debtor will not do anything to harm Lender's position. Debtor
will keep, and allow Lender reasonable access to, books, records, and accounts
about the Property and Debtor's business in general. If this Security Agreement
covers chattel paper or instruments, either as original collateral or proceeds
of the Property. Debtor will note Lender's interest on the face of the chattel
paper or instruments.

Use, Location, and Protection of the Property. Debtor will keep the Property in
Debtor's possession and in good repair. Debtor will use the Property only for
commercial or agricultural purposes and will not change this specified use
without Lender's prior written consent. Lender has the right of reasonable
access to inspect the Property and Debtor will immediately inform Lender of any
loss or damage to the Property. Debtor will not cause or permit waste to the
Property. Debtor will keep the Property at Debtor's address unless Lender and
Debtor agree that it may be kept at another location. If the Property is to be
used in other states, Debtor will give Lender a list of those states. Debtor
will notify Lender in writing and obtain Lender's prior written consent to any
change in location of any of the Property. The location of the Property is given
to aid in the identification of the Property and does not in any way limit the
scope of the security interest granted to Lender. Debtor will not use the
Property in violation of any law. Debtor will notify Lender in writing prior to
any change in Debtor's address, name or, if any organization, any change in
Debtor's identity or structure. Debtor will pay all taxes and assessments levied
or assessed against Debtor or the Property and provide timely proof of payment
of these taxes and assessments upon request.

Selling, Leasing, or Encumbering the Property. Debtor will not sell, offer to
sell, lease, grant a security interest in, or otherwise transfer or encumber the
Property without Lender's prior written permission, except for inventory sold in
the ordinary course of business at fair market value, or at a minimum price
established between Debtor and Lender. If Debtor is in default under this
Security Agreement, Debtor may not sell the inventory portion of the Property
even in the ordinary course of business. Lender's permission to sell the
Property may be reasonably withheld without regard to the creditworthiness of
any buyer or transferee. Debtor will not permit the Property to be the subject
of any court order affecting Debtor's rights to the Property in any action by
anyone other than Lender.

Insurance. Debtor will keep the tangible Property insured against risks
reasonably associated with the Property. This insurance will last until the
Property is released from this Security Agreement. Lender may apply insurance
proceeds toward what is owed on the Secured Debts. Lender may require added
security as a condition of permitting any insurance proceeds to be used to
repair or replace the Property. If Lender acquires the Property in damaged
condition, Debtor's right to any insurance policies and proceeds will pass to
Lender to the extent of the Secured Debts. If Debtor fails to keep the Property
insured, Lender may obtain insurance to protect Lender's interest in the
Property and may include coverages not originally required of Debtor, may be
written by a company other than one Debtor would choose, and may incur a higher
rate than Debtor could obtain if Debtor purchased the insurance.

Additional Duties Specific to Accounts. If the Property includes Accounts,
Debtor will not settle any Account for less than its full value without Lender's
written permission. Debtor will collect all Accounts in the ordinary course of
business. Debtor will not dispose of the Accounts by assignment without Lender's
prior written consent. At Lender's request, Debtor will notify account debtors
that their Accounts have been assigned to Lender and should be paid directly to
Lender. Debtor will deliver the Accounts to Lender at Lender's request. If
Lender asks Debtor to pay Lender the full price on any returned items or items
retaken by Debtor, Debtor will do so. Debtor will make no material change in the
terms of any Account, and Debtor will give Lender any statements, reports,
certificates, lists of account debtors, invoices applicable to each Account, and
other data pertaining to the Accounts as Lender may request.

Additional Duties Specific to Farm Products. In this paragraph the terms "farm
products," "buyers," "commission merchants," and "selling agents" have the
meanings given to them in the Food Security Act of 1985. If the Property
includes farm products, Debtor will provide Lender, at Lender's request, a
written list of the buyers, commission merchants, or selling agents to or
through whom Debtor may sell Debtor's farm products. Debtor remains subject to
all applicable penalties for selling Debtor's farm products in violation of this
Security Agreement and the Food Security Act of 1985. If the Property includes
crops growing or to be grown, Debtor agrees to plant, cultivate, and harvest the
crops in due season. Debtor will not use loan proceeds for a purpose that will
contribute to excessive erosion of highly erodible land or to the conversion of
wetlands to produce an agricultural commodity, as explained by federal law.

AUTHORITY TO PERFORM. Debtor authorizes Lender to do anything Lender deems
reasonably necessary to protect the Property and Lender's interest in the
Property. If Debtor fails to perform any of Debtor's duties under this Security
Agreement, Lender is authorized, with notice to Debtor, to perform the duties or
cause them to be performed. These authorizations include, but are not limited
to, permission to pay for the repair, maintenance, and preservation of the
Property and take any action to realize the value of the Property. Lender's
authority to perform for Debtor does not create an obligation to perform, and
Lender's failure to perform will not preclude Lender from exercising any other
rights under the law or this Security Agreement. If Lender performs for Debtor,
Lender will use reasonable care. Reasonable care will not include any steps
necessary to preserve rights against prior parties or any duty to take action in
connection with the management of the Property.

If Lender comes into possession of the Property, Lender will preserve and
protect the Property to the extent required by law. Lender's duty of care with
respect to the Property will be satisfied if Lender exercises reasonable care in
the safekeeping of the Property or in the selection of a third party in
possession of the Property. Lender may enforce the obligations of an account
debtor or other person obligated on the Property.

Lender may exercise Debtor's rights with respect to the account debtor's or
other person's obligations to make payment or otherwise render performance to
Debtor, and enforce any security interest that secures such obligations.

PURCHASE MONEY SECURITY INTEREST. This Agreement creates a Purchase Money
Security Interest to the extent the Secured Debts are used to purchase or
acquire rights in the Property. The portion of the Property purchased with loan
proceeds will remain subject to the Purchase Money Security Interest until the
Secured Debts are paid in full. Debtor authorizes Lender, at Lender's option, to
disburse the loan proceeds directly to the seller of the Property. Payments on
any non-purchase money loan also secured by this Security Agreement will not be
applied to the purchase money loan. Payments on the purchase money loan will be
applied first to the non-purchase money portion of the loan, if any, and then to
the purchase money portion in the order in which the purchase money Property was
acquired. If the purchase money Property was acquired at the same time, then
payments will be applied in the order Lender selects. No security interest will
be terminated by application of this formula.

COLLATERAL ACCOUNT. If required by Lender, Debtor will establish and maintain a
demand deposit account, referred to as a Collateral Account, and will
immediately deposit all payments from Account Debtors and other proceeds from
the Property, referred to as Funds, in payment of and as security for the
Secured Debts. Account Debtor is any person who is obligated on an account,
chattel paper, or general intangible. Debtor will continue to deposit these
Funds in this Collateral Account until Lender informs Debtor in writing that it
is no longer necessary to do so. Debtor may withdraw from this Collateral
Account only upon Lender's prior written consent. Debtor will execute any
documents that are necessary to establish and maintain the Collateral Account
and Lender's control over it. The Funds will be deposited in the form received.
Pending deposit, Debtor will not commingle the Funds with any of Debtor's other
property. Lender has the right at any time, without notice, to withdraw Funds
from the Collateral Account and apply those Funds to the Secured Debts or
release any of the Funds to Debtor.

DEFAULT. Debtor will be in default if Debtor or Borrower (if not the same) fails
to perform any condition, covenant, or make required payments under the Loan
Agreement or Debtor fails to perform under this Security Agreement.

REMEDIES. If Debtor is in default, Lender has the option to do any one or more
of the following in addition to the remedies provided in the Loan Agreements and
other remedies provided by law.

(1) Assembly of Property. Lender may require Debtor to gather the Property and
make it available to Lender in a reasonable fashion if allowed by law.

(2) Repossession. Lender may repossess (unless prohibited by law) or otherwise
seize the Property as provided by law. Lender may hold, use, and operate
Debtor's property as necessary to preserve the Property or its value without
compensation to Debtor.

(3) Sale of Property. Lender may sell the Property as provided by law. Lender
may apply the proceeds of the Property to Lender's expenses, attorneys' fees and
legal expenses (to the extent allowed by law), and any remaining Secured Debt.
If what Lender receives from the sale of the Property does not satisfy the
Secured Debt, Debtor will be liable for the remaining balance (where permitted
by law).

WAIVER. Debtor waives all claims for loss and damage causes by Lender's acts or
omissions where Lender acted reasonably and in good faith. Except to the extent
prohibited by law. Debtor waives all rights Debtor has now or in the future as a
homestead exemption in the Property.

PERFECTION OF SECURITY INTEREST. Debtor authorizes Lender to file a financing
statement covering the Property. Debtor will comply with, facilitate, and
otherwise assist Lender in connection with obtaining possession or control over
the Property for purposes of perfecting Lender's interest under the Uniform
Commercial Code.

ADDITIONAL DOCUMENTS. Debtor will provide any additional information Lender
requests, including financial statements and documents relating to the Property.
Debtor represents that all documents and information submitted to Lender will be
true, correct, and complete as of the date submitted and will update the
documents or information as necessary to give Lender a current and accurate
assessment of Debtor's affairs. Debtor agrees to sign, deliver, and file any
additional documents, certifications, or records that Lender requires to
perfect, continue, and preserve Debtor's obligations and Lender's rights under
this Security Agreement and to verify Lender's lien status on the Property.
Debtor authorizes Lender to sign, authorize, and execute any documents on
Debtor's behalf in order to preserve or protect Lender's interest in the
Property.

NOTICES. Unless otherwise required by law, any notice will be given by
delivering it or mailing it by first class mail to the appropriate party's
address as indicated in this Security Agreement, or any other address designated
in writing.

Notice to one party is notice to all parties.

WAIVER/CONFESSION (LOUISIANA ONLY). Debtor waives the benefit of appraisal as
provided in the Louisiana Code of Civil Procedure and all other laws with regard
to appraisal upon sales. For purposes of foreclosure under Louisiana executory
process procedures, Debtor confesses judgement in Lender's favor up to the full
amount of the Secured Debts including collection costs and attorneys' fees.

                                                                   (page 2 of 2)