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                                                                       EXHIBIT 8


                               SECOND AMENDMENT TO
                         THE DEKALB GENETICS CORPORATION
                           DEFERRED COMPENSATION PLAN



                  WHEREAS, DEKALB Genetics Corporation, a Delaware corporation,
with its principal place of business in DeKalb, Illinois (the "Company"), has
heretofore adopted and maintains for the benefit of certain of its employees a
nonqualified deferred compensation plan which is designated the "DEKALB Genetics
Corporation Deferred Compensation Plan" (the "Plan"); and

                  WHEREAS, the Company desires to amend the Plan in
certain respects;

                  NOW, THEREFORE, pursuant to the power of amendment contained
in Section 8.1 of the Plan, the Plan is hereby amended, effective immediately as
of the date of the consummation of the "Offer" (as that term is defined in the
Agreement and Plan of Merger dated as of May 8, 1998 among Monsanto Company, a
Delaware corporation ("Parent"), Corn Acquisition Corporation, a Delaware
corporation and a wholly-owned subsidiary of Parent ("Sub"), and the Company),
as follows:





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                  1. Article II is hereby amended to add the following sentence
at the end thereof:

                  Notwithstanding the foregoing, with respect to any Plan Year
                  which contains the day (the "Purchase Date") of the
                  consummation of the "Offer" (as that term is defined in the
                  Agreement and Plan of Merger dated as of May 8, 1998 among
                  Monsanto Company, a Delaware corporation ("Parent"), Corn
                  Acquisition Corporation, a Delaware corporation and a
                  wholly-owned subsidiary of Parent ("Sub"), and the Company) or
                  the day (the "four-month anniversary") which is exactly 120
                  days immediately following such Purchase Date, any employee of
                  a Related Employer who in the reasonable judgement of the
                  Committee can be considered to be a member of a select group
                  of management or highly compensated employees, within the
                  meaning of Section 201 of the Employee Retirement Income
                  Security Act of 1974, as amended, shall participate in this
                  Plan.

                  2. Section 3.5 of the Plan is hereby amended to add the
following two paragraphs after the first sentence thereof:

                  In addition, the Company shall make a Supplemental Company
                  Discretionary Contribution for the benefit of each eligible
                  Participant for the Plan Year during which occurs the day (the
                  "four-month anniversary") which is exactly 120 days
                  immediately following the day (the "Purchase Date") of the
                  consummation of the "Offer" (as that term is defined in the
                  Agreement and Plan of Merger dated as of May 8, 1998 among
                  Monsanto Company, a Delaware corporation ("Parent"), Corn
                  Acquisition Corporation, a Delaware corporation and a
                  wholly-owned subsidiary of Parent ("Sub"), and the Company).
                  The amount contributed for such Plan Year for each eligible
                  Participant shall be an amount equal to 2% of such
                  Participant's additional base pay and salary he would have
                  earned during the remainder of such Plan Year during which
                  occurs his termination of employment if such base pay and
                  salary would have continued for the remainder of that year at
                  the same rate in effect upon his termination of employment. An
                  "eligible Participant" for purposes of this paragraph is (i) a
                  Participant who is employed by a Related Employer both at such
                  Purchase Date and on the four-month anniversary and whose
                  employment terminates with all Related Employers before the
                  end of the Plan Year


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                  during which occurs the four-month anniversary and (ii) who is
                  a "highly compensated employee" as defined in Section 414(q)
                  of the Code for the Plan Year during which occurs the
                  four-month anniversary or who is such a highly compensated
                  employee for the Plan Year which precedes the Plan Year during
                  which occurs the four-month anniversary. 

                  In addition, the Company shall make a Supplemental Company
                  Discretionary Contribution for the benefit of each eligible
                  terminated Participant for the Plan Year during which occurs
                  such terminated Participant's termination of employment after
                  the day (the "Purchase Date") of the consummation of the
                  "Offer" (as that term is defined in the Agreement and Plan of
                  Merger dated as of May 8, 1998 among Monsanto Company, a
                  Delaware corporation ("Parent"), Corn Acquisition Corporation,
                  a Delaware corporation and a wholly-owned subsidiary of Parent
                  ("Sub"), and the Company). The amount contributed for such
                  Plan Year for each eligible terminated Participant shall be 2%
                  of such Participant's Compensation (as such term is defined in
                  the Qualified Plan but without regard to the limitation
                  imposed by Section 401(a)(17) of the Code) for such Plan Year.
                  An "eligible terminated Participant" for purposes of this
                  paragraph is a Participant who is (i) employed by a Related
                  Employer at such Purchase Date whose employment is
                  involuntarily terminated by his employer without cause after
                  the Purchase Date and prior to the day (the "four-month
                  anniversary") which is exactly 120 days immediately following
                  the Purchase Date and (ii) a "highly compensated employee" as
                  defined in Section 414(q) of the Code for the Plan Year during
                  which occurs his termination of employment or is such a highly
                  compensated employee for the Plan Year which precedes the Plan
                  Year during which occurs his termination of employment. For
                  purposes of the foregoing, "cause" shall be defined as such
                  term is defined in the Merger Agreement. In the case of an
                  eligible terminated Participant whose employment with all
                  Related Employers terminates before the end of the Plan Year
                  during which occurs the Purchase Date or the four-month
                  anniversary, for purposes of this paragraph his Compensation
                  for the Plan Year during which occurs his termination of
                  employment shall be his actual Compensation for such Plan Year
                  plus the additional base pay and salary he would have earned
                  during the remainder of such Plan Year if such base pay and
                  salary would have continued for the remainder of that year at


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                  the same rate in effect upon his termination of
                  employment.
                  3.  Section 5.2 of the Plan is hereby amended to read
as follows:

         5.2      Supplemental Company Contribution Account. A Participant shall
                  be one hundred percent (100%) vested in his Supplemental
                  Company Contribution Account on the first to occur of the
                  following:

                      (a)     His attainment of Normal Retirement Age while
                              employed by any Related Employer;

                      (b)     His termination of employment with all
                              Related Employers due to his Total and
                              Permanent Disability;

                      (c)     His termination of employment with all
                              Related Employers due to his death;

                      (d)     His completion of five (5) Years of Service
                              for Vesting (as such term is defined in the
                              Qualified Plan); or

                      (e)     His active employment with any Related
                              Employer on the day (the "Purchase Date") of
                              the consummation of the "Offer" (as that term
                              is defined in the Agreement and Plan of
                              Merger dated as of May 8, 1998 among Monsanto
                              Company, a Delaware corporation ("Parent"),
                              Corn Acquisition Corporation, a Delaware
                              corporation and a wholly-owned subsidiary of
                              Parent ("Sub"), and the Company).

                  4.  Section 5.3 of the Plan is hereby amended to read
as follows:

         5.3 Termination of Employment. A Participant who upon his termination
         of employment with all Related Employers is not one hundred percent
         (100%) vested in his Supplemental Company Contribution Account pursuant
         to Section 5.2 shall be vested in the percentage of the value of his
         Supplemental Company Contribution Account set forth in the following
         table:

                    Number of Years of                  Vesting


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            Service for Vesting               Percentage
            -------------------               ----------
                                            
               Less than 1                         0%
                    1                             20%
                    2                             40%
                    3                             60%
                    4                             80%
               5 or more                         100%


         Sections 6.03(b), (c) and (d) of the Qualified Plan, dealing with
         Participants who return to the employ of the Company or a Related
         Employer, shall apply to the non-vested portion of the Supplemental
         Company Contribution Account.


                  5. Section 8.1 of the Plan is hereby amended to read as
follows:

         8.1      Right to Amend, Suspend or Terminate. Subject to this Section
                  and Section 8.2, the Company reserves the right at any time
                  and from time to time to amend, suspend or terminate this Plan
                  by action of its Board of Directors without the consent of any
                  Participant, Beneficiary or other person claiming a right
                  under this Plan. Notwithstanding any provision of this Plan to
                  the contrary, no amendment of this Plan shall reduce the
                  benefits of any Participant below the amount to which he has
                  become vested pursuant to Article 5 prior to the date of
                  amendment.

                  6. Section 8.2 of the Plan is hereby amended to read as
follows:

         8.2      Effect of Amendment or Termination. Notwithstanding any
                  provision of this Plan to the contrary, no amendment or
                  termination of this Plan shall directly or indirectly reduce
                  the vested balance of any Supplemental Employee Salary
                  Reduction Account or Supplemental Company Contribution Account
                  held hereunder as of the effective date of such amendment or
                  termination, or delay the time at which any Participant is
                  entitled to a distribution hereunder. Upon termination of this
                  Plan, distribution of amounts in any Supplemental Employee
                  Salary Reduction Account or Supplemental Company Contribution
                  Account shall be made to the Participant or his Beneficiary in
                  the manner and at the time described in Section 6.1 of this
                  Plan. No additional credits of Supplemental Employee Salary


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                  Reduction Contributions, Supplemental Company Matching
                  Contributions, Supplemental Company Compensation Based
                  Contributions and Supplemental Company Discretionary
                  Contributions shall be made on behalf of any Participant after
                  termination of this Plan. Notwithstanding any provision of
                  this Plan to the contrary, in the event of any amendment or
                  termination of this Plan, the Company shall continue to credit
                  interest to Supplemental Employee Salary Reduction Accounts
                  and Supplemental Company Contribution Accounts pursuant to
                  Article IV, until the balance of all such accounts have been
                  fully distributed to the Participants or their Beneficiaries
                  as described in Section 4.1. Notwithstanding any provision of
                  this Plan to the contrary, this Plan shall not be amended or
                  terminated in any manner which would (i) adversely affect an
                  employee's ability to participate in the Plan pursuant to the
                  final sentence of Article II, (ii) prevent a Participant's
                  Supplemental Company Contribution Account from being credited
                  pursuant to Section 3.5 with a Supplemental Company
                  Discretionary Contribution based on the Qualified Plan Company
                  Discretionary Contribution to be made for such Participant
                  pursuant to Section 6.02(e) of the Qualified Plan, (iii)
                  prevent a Participant's Supplemental Company Contribution
                  Account from being credited with a Supplemental Company
                  Discretionary Contribution pursuant to the second or third
                  paragraphs of Section 3.5 or (iv) reduce the amount of any
                  such Supplemental Company Discretionary Contribution to be
                  credited to a Participant's Supplemental Company Contribution
                  Account.



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     IN WITNESS WHEREOF, the Company has adopted this instrument by causing it
to be executed by its duly authorized officer on this 8th day of May, 1998.


                                            DEKALB GENETICS CORPORATION



                                            By: /s/ John H. Witmer, Jr.
                                               ------------------------------

                                            Title: Senior Vice President
                                                  ---------------------------





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