<PAGE>


                                 PROMISSORY NOTE
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     Principal          Loan Date       Maturity       Loan No      Call/Coll        Account      Officer    Initials
<S>                    <C>            <C>            <C>          <C>              <C>           <C>        <C>
   $20,000,000.00       12-19-2001     06-19-2003       53455         47/400         119284         JH
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  References in the shaded area are for Lender's use only and do not limit the
         applicability of this document to any particular loan or item.

               Any item above containing "* * *" has been omitted
                        due to text length limitations.

<TABLE>
<CAPTION>
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<S>        <C>                                             <C>          <C>
Borrower:    HUSKER AG PROCESSING, LLC (TIN:  47-0836953)     LENDER:      STEARNS BANK NATIONAL ASSOCIATION
             PO BOX 10                                                     4191 SO 2ND ST
             PLAINVIEW, NE 68769                                           PO BOX 7338
                                                                           ST CLOUD, MN 56302
=========================================================================================================================
Principal Amount:   $20,000,000.00        Initial Rate:   5.000%             Date of Note:   December 19, 2001
</TABLE>

PROMISE TO PAY. HUSKER AG PROCESSING, LLC ("Borrower") promises to pay to
STEARNS BANK NATIONAL ASSOCIATION ("Lender"), on order, in lawful money of the
United States of America, the principal amount of Twenty Million & 00/100
Dollars ($20,000,000.00) or so much as may be outstanding, together with
interest on the unpaid outstanding principal balance of each advance. Interest
shall be calculated from the date of each advance until repayment of each
advance.

PAYMENT. Borrower will pay this loan on demand. Payment in full is due
immediately upon Lender's demand. If no demand is made, Borrower will pay this
loan in one payment of all outstanding principal plus all accrued unpaid
interest on June 19, 2003. In addition, Borrower will pay regular monthly
payments of all accrued unpaid interest due as of each payment date, beginning
January 19, 2002, with all subsequent interest payments to be due on the same
day of each month after that. Unless otherwise agreed or required by applicable
law, payments will be applied first to accrued unpaid interest, then to
principal, and any remaining amount to any unpaid collection costs. The annual
interest rate for this Note is computed on a 365/360 basis; that is, by applying
the ratio of the annual interest rate over a year of 360 days, multiplied by the
outstanding principal balance, multiplied by the actual number of days the
principal balance is outstanding. Borrower will pay Lender at Lender's address
shown above or at such place as Lender may designate in writing.

VARIABLE INTEREST RATE. The interest rate on this Note is subject to change from
time to time based on changes in an independent index which is the WALL STREET
JOURNAL PRIME RATE (the "Index"). The Index is not necessarily the lowest rate
charged by Lender on its loans. If the Index become unavailable during the term
of this loan, Lender may designate a substitute index after notice to Borrower.
Lender will tell Borrower the current Index rate upon Borrower's request. The
interest rate change will not occur more often than each DAY. Borrower
understands that Lender may make loans based on other rates as well. The Index
currently is 4.750% per annum. The interest rate to be applied to the unpaid
principal balance of this Note will be at a rate of 0.250 percentage points over
the Index, resulting in an initial rate of 5.000% per annum. NOTICE: Under no
circumstances will the interest rate on this Note be more than the maximum rate
allowed by applicable law.

PREPAYMENT. Borrower may pay without penalty all or a portion of the amount owed
earlier than it is due. Early payments will not, unless agreed to by Lender in
writing, relieve Borrower of Borrower's obligation to continue to make payments
of accrued unpaid interest. Rather, early payments will reduce the principal
balance due. Borrower agrees not to send Lender payments marked "paid in full",
"without recourse", or similar language. If Borrower sends such a payment,
Lender may accept it without losing any of Lender's rights under this Note, and
Borrower will remain obligated to pay any further amount owed to Lender. All
written communications concerning disputed amounts, including any check or other
payment instrument that indicates that the payment constitutes "payment in full"
of the amount owed or that is tendered with other conditions or limitations or
as full satisfaction of a disputed amount must be mailed or delivered to:
STEARNS BANK NATIONAL ASSOCIATION, 4191 SO 2ND ST, ST CLOUD, MN 56302-7338.

INTEREST AFTER DEFAULT. Upon default, including failure to pay upon final
maturity, the total sum due under this Note will bear interest from the date of
acceleration or maturity at the variable interest rate on this Note. The
interest rate will not exceed the maximum rate permitted by applicable law.

DEFAULT. Each of the following shall constitute an event of default ("Event of
Default") under this note:

     Payment Default. Borrower fails to make any payment when due under this
     Note.

     Other Defaults. Borrower fails to comply with or to perform any other term,
     obligation, covenant or condition contained in this Note or in any of the
     related documents or to comply with or to perform any term, obligation,
     covenant or condition contained in any other agreement between Lender and
     Borrower.

     Default in Favor of Third Party. Borrower or any Grantor defaults under any
     loan, extension of credit, security agreement, purchase or sales agreement,
     or any other agreement, in favor of any other creditor or person that may
     materially affect any of Borrower's property or Borrower's ability to repay
     this Note or perform Borrower's obligations under this Note or any of the
     related documents.

     False Statements. Any warranty, representation or statement made or
     furnished to Lender by Borrower or on Borrower's behalf under this Note or
     the related documents is false or misleading in any material respect,
     either now or at the time made or furnished or becomes false or misleading
     at any time thereafter.

     Insolvency. The dissolution of Borrower (regardless of whether election to
     continue is made), or any other termination of Borrower's existence as a
     going business, the insolvency of the Borrower, the appointment of a
     receiver for any part of Borrower's property, any assignment for the
     benefit of creditors, any type of creditor workout, or the commencement of
     any proceeding under any bankruptcy or insolvency laws by or against
     Borrower.

     Creditor or Forfeiture Proceedings. Commencement of foreclosure or
     forfeiture proceedings, whether by judicial proceeding, self-help,
     repossession or any other method, by any creditor of Borrower or by any
     governmental agency against any collateral securing the loan. This includes
     a garnishment of any of Borrower's accounts, including deposit accounts,
     with Lender. However, this Event of Default shall not apply if there is a
     good faith dispute by Borrower as to the validity or reasonableness of the
     claim which is the basis of the creditor or forfeiture proceeding and if
     Borrower gives Lender written notice of the creditor or forfeiture
     proceeding and deposits with Lender monies or a surety bond for the
     creditor or forfeiture proceeding, in an amount determined by Lender, in
     its sole discretion, as being an adequate reserve or bond for the dispute.

     Adverse Change. A material adverse change occurs in Borrower's financial
     condition, or Lender believes the prospect of payment or performance of
     this Note is impaired.

     Insecurity. Lender in good faith believes itself insecure.

     Cure Provisions. If any default, other than a default in payment is curable
     and if Borrower has not been given a notice of a breach of the same
     provision of this Note within the preceding twelve (12) months, it may be
     cured (and no event of default will have occurred) if Borrower, after

<PAGE>

                                PROMISSORY NOTE
Loan No:  53455                   (Continued)                             Page 2
================================================================================

     receiving written notice from Lender demanding cure of such default: (1)
     cures the default within fifteen (15) days; or (2) if the cure requires
     more than fifteen (15) days, immediately initiates steps which Lender deems
     in Lender's sole discretion to be sufficient to cure the default and
     thereafter continues and completes all reasonable and necessary steps
     sufficient to produce compliance as soon as reasonably practical.

LENDER'S RIGHTS. Upon default, Lender may declare the entire unpaid principal
balance on this Note and all accrued unpaid interest immediately due, and then
Borrower will pay that amount.

ATTORNEYS' FEES; EXPENSES. Lender may hire or pay someone else to help collect
this Note if Borrower does not pay. Borrower will pay Lender that amount. This
includes, subject to any limits under applicable law, Lender's reasonable
attorneys' fees and Lender's legal expenses, whether or not there is a lawsuit,
including reasonable attorneys' fees, expenses for bankruptcy proceedings
(including efforts to modify or vacate any automatic stay or injunction), and
appeals. If not prohibited by applicable law, Borrower will also pay any court
costs, in addition to all other sums provided by law.

JURY WAIVER. Lender and Borrower hereby waive the right to any jury trial in any
action, proceeding, or counterclaim brought by either Lender or Borrower against
the other.

GOVERNING LAW. This Note will be governed by, construed and enforced in
accordance with federal law and the laws of the State of Minnesota. This Note
has been accepted by Lender in the State of Minnesota.

RIGHT OF SETOFF. To the extent permitted by applicable law, Lender reserves a
right of setoff in all Borrower's accounts with Lender (whether checking,
savings, or some other account). This includes all accounts Borrower holds
jointly with someone else and all accounts Borrower may open in the future.
However, this does not include any IRA or Keogh accounts, or any trust accounts
for which setoff would be prohibited by law. Borrower authorizes Lender, to the
extent permitted by applicable law, to charge or setoff all sums owing on the
indebtedness against any and all such accounts, and, at Lender's option, to
administratively freeze all such accounts to allow Lender to protect Lender's
charge and setoff rights provided in this paragraph.

COLLATERAL. Borrower acknowledges this Note is secured by COLLATERAL AS
DESCRIBED IN THE FOLLOWING DOCUMENTS: DEED OF TRUST, ASSIGNMENT OF RENTS AND
SECURITY AGREEMENT FROM BORROWER TO LENDER DATED 12-19-01.

LINE OF CREDIT. This Note evidences a straight line of credit. Once the total
amount of principal has been advanced, Borrower is not entitled to further loan
advances. Advances under this Note, as well as directions for payment from
Borrower's accounts, may be requested orally or in writing by Borrower or by an
authorized person. Lender may, but need not, require that all oral requests be
confirmed in writing. Borrower agrees to be liable for all sums either: (A)
advanced in accordance with the instructions of an authorized person or (B)
credited to any of Borrower's accounts with Lender. The unpaid principal balance
owing on this Note at any time may be evidenced by endorsements on this Note or
by Lender's internal records, including daily computer print-outs. Lender will
have no obligation to advance funds under this Note if: (A) Borrower or any
guarantor is in default under the terms of this Note or any agreement that
Borrower or any guarantor has with Lender, including any agreement made in
connection with the signing of this Note; (B) Borrower or any guarantor ceases
doing business or is insolvent; (C) any guarantor seeks, claims or otherwise
attempts to limit, modify or revoke such guarantor's guarantee of this Note or
any other loan with Lender; (D) Borrower has applied funds provided pursuant to
this Note for purposes other than those authorized by Lender; or (E) Lender in
good faith believes itself insecure.

LATE CHARGE. SHOULD BORROWER FAIL TO PAY ANY PAYMENT REQUIRED DURING THE TERM OF
THIS LOAN, OR TO PAY THE INDEBTEDNESS UPON THE MATURITY OF THIS LOAN, AND SHOULD
ANY SUCH AMOUNT REMAIN UNPAID FOR A PERIOD OF TEN (10) DAYS FOLLOWING ITS DUE
DATE, THEN BORROWER AGREES AND COVENANTS TO PAY TO LENDER A LATE CHARGE IN THE
AMOUNT OF FIVE PERCENT (5%) OF ANY SUCH AMOUNT, INCLUDING THE AMOUNT DUE AND
PAYABLE AT MATURITY.

SUCCESSOR INTERESTS. The terms of this Note shall be binding upon Borrower, and
upon Borrower's heirs, personal representatives, successors and assigns, and
shall inure to the benefit of Lender and its successors and assigns.

GENERAL PROVISIONS. This Note is payable on demand. The inclusion of specific
default provisions or rights of Lender shall not preclude Lender's right to
declare payment of this Note on its demand. Lender may delay or forgo enforcing
any of its rights or remedies under this Note without losing them. Borrower and
any other person who signs, guarantees or endorses this Note, to the extent
allowed by law, waive presentment, demand for payment, and notice of dishonor.
Upon any change in the terms of this Note, and unless otherwise expressly stated
in writing, no party who signs this Note, whether as maker, guarantor,
accommodation maker or endorser, shall be released from liability. All such
parties agree that Lender may renew or extend (repeatedly and for any length of
time) this loan or release any party or guarantor or collateral; or impair, fail
to realize upon or perfect Lender's security interest in the collateral; and
take any other action deemed necessary by Lender without the consent of or
notice to anyone. All such parties also agree that Lender may modify this loan
without the consent of or notice to anyone other than the party with whom the
modification is made. The obligations under this Note are joint and several.

SECTION DISCLOSURE.  This loan is made under Minnesota Statutes, Section 47.59.


PRIOR TO SIGNING THIS NOTE, BORROWER READ AND UNDERSTOOD ALL OF THE PROVISIONS
OF THIS NOTE, INCLUDING THE VARIABLE INTEREST RATE PROVISIONS, BORROWER AGREES
TO THE TERMS OF THE NOTE.

BORROWER ACKNOWLEDGES RECEIPT OF A COMPLETED COPY OF THIS PROMISSORY NOTE.

THIS NOTE IS GIVEN UNDER SEAL AND IT IS INTENDED THAT THIS NOTE IS AND SHALL
CONSTITUTE AND HAVE THE EFFECT OF A SEALED INSTRUMENT ACCORDING TO LAW.

BORROWER:

HUSKER AG PROCESSING, LLC
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<CAPTION>
<S>                                              <C>

By:  /s/ Gary Kuester                 (Seal)      By: /s/ Jack Frahm                  (Seal)
     --------------------------------                 -------------------------------
     GARY KUESTER, Chairman of HUSKER AG              JACK FRAHM, Secretary of HUSKER AG
     PROCESSING, LLC                                  PROCESSING, LLC

By:  /s/ Fred Knievel                 (Seal)
     --------------------------------
     FRED KNIEVEL, Treasurer of HUSKER AG
     PROCESSING, LLC

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