Exhibit 4.1
                                                                     -----------
                                   Amendment 1
                              PCS U. S. Employees'
                                  Savings Plan
                        (Effective as of January 1, 1999)

Whereas, PCS Administration (USA), Inc. ("Sponsor") is the sponsor of the PCS U.
S. Employees' Savings Plan ("U. S. Plan");

Whereas, PCS Nitrogen Inc. is the sponsor of the PCS Nitrogen 401(k) Savings
Plan ("Nitrogen Plan");

Whereas, certain former participants in the Nitrogen Plan are now eligible to
participate in the U. S. Plan;

Whereas, Moab Salt, Inc., an Employer under the U. S. Plan has been sold; and

Whereas, the Sponsor desires to amend the Plan to reflect recent IRS rules and
to otherwise clarify the U. S. Plan;

Now, Therefore, Be It Resolved, that the U. S. Plan is amended as follows,
effective as of January 1, 1999 unless provided otherwise:

1.   The first sentence of section 4.5 (concerning matching contributions) is
     amended by replacing "for the entire Plan Year" with "for each payroll
     period", and by amending the first sentence of the second paragraph to read
     as follows:

    "The Employer Matching Contributions shall be credited to the Participant's
     Employer Matching Contributions Account and shall be paid to the Trustee
     monthly to the extent practicable, but in no event later than the earlier
     of--

     (a)  the time required for the filing of the Employer's federal income tax
          return for its fiscal year in which the applicable Plan Year ends,

     (b)  12 months after the close of the Plan Year, or

     (c)  for Employer Matching Contributions relating to Before-Tax or
          After-Tax Employee Contributions made after May 1, 2000, the last day
          of the calendar quarter that follows the calendar quarter in which
          such Employee Contributions were made."

2.   Subparagraph (B) of section 4.8(f) shall be reformatted so that it appears
     as follows:

     "(B) the Actual Contribution Percentage for the group of Highly Compensated
          Employees who are Eligible Employees

     shall not exceed the Aggregate Limitation described in paragraph (2)."

3.   The last sentence of the second paragraph of section 5.1(a) (concerning the
     Company Stock Fund) is amended by replacing "if such person (1) is not the
     Company, an Affiliate, or any Employee" with "if such person (1) is not the
     Sponsor, an Affiliate, or any Employee".

4.   In section 6.3(a), the last sentence of the second paragraph is amended to
     read as follows:

    "Stock may be distributed only if the Participant elects a Lump Sum
Distribution."

5.   Appendix A (listing the participating Employers) is amended by striking
     "Moab Salt, Inc." and replacing it with "Moab Salt, Inc., effective January
     1, 1999 to February 18, 2000."

6.   The Plan is amended by adding the following new Supplement:

   "Supplement C. PCS Nitrogen, Inc.

     C.1  Asset Transfer; Transfer Accounts

     (a)  In General. Effective January 1, 2000, the account balances of those
          Eligible Employees of PCS Nitrogen, Inc. that were held under the PCS
          Nitrogen 401(k) Savings Plan ("Nitrogen Plan") were transferred to
          this Plan. These account balances shall be credited to the appropriate
          Before-Tax, After-Tax, and Rollover Accounts under this Plan. The
          amounts credited to the employer contributions account under the
          Nitrogen Plan shall be credited to a separate account ("Transfer
          Account") under this Plan. The Transfer Account includes qualifying
          employer securities ("Company Stock") as defined in ERISA section
          407(d)(5) that had been originally acquired through a loan to a
          predecessor of the Nitrogen Plan, the Arcadian Corporation Employee
          Stock Ownership Plan ("ESOP") and then replaced by stock of Potash
          Corporation of Saskatchewan upon that Corporation's acquisition of
          Arcadian Corporation, later renamed PCS Nitrogen, Inc. The loan
          satisfied the requirements of ERISA section 408(b)(3) and Code section
          4975(d)(3) for a loan to a plan made by, or guaranteed by, a
          disqualified person and has been fully discharged.

     (b)  Vesting. The Transfer Account described in this Supplement is fully
          vested in the case of a person who is an Employee of the Sponsor or an
          Affiliate on January 1, 2000.

     (c)  In-Service Withdrawals. Amounts credited to the Transfer Account may
          be withdrawn or distributed only if the Participant terminates
          employment, becomes Disabled, attains age 59 1/2, or satisfies the
          requirements of section 7.4 (relating to hardship withdrawals).

     (d)  Investment Direction. A Participant may elect to sell Company Stock
          and transfer the proceeds to another investment pursuant to section
          5.1(c).

     (e)  Distribution Methods; Right to Demand Stock Distribution. The
          applicable form of payment under section 6.3(a) shall also apply to
          the Transfer Account. However, notwithstanding section 6.3(a), a
          Participant may elect to receive a distribution from the Transfer
          Account in the form of Company Stock or cash, or both, and may receive
          Company Stock notwithstanding the election of an Installment Payout.
          The preceding sentence does not apply to the extent that Company Stock
          has been sold pursuant to a Participant's investment direction under
          subsection (d).

     (f)  Special ESOP Rules.

          (1)    Nonterminable Protections and Rights. Except as provided in
                 paragraph (2) or by law, no Company Stock credited to the
                 Transfer Account may be subject to a put, call, or other
                 option, or buy-sell or similar arrangement when held by and
                 when distributed by the Trust Fund. The protections and rights
                 granted by this paragraph and the put option rights granted by
                 paragraph (2) are nonterminable, and such protections and
                 rights shall continue to exist under the terms of this Plan so
                 long as any Company Stock credited to the Transfer Account is
                 held by the Trust Fund or by a Participant or other person for
                 whose benefit such protections and rights have been created.

          (2)    Put Option If Stock is not Readily Tradable.

                 (A)    In General. When Company Stock is distributed to a
                        Participant, the Participant shall have the right to
                        require the Employer to repurchase such Company Stock
                        pursuant to subparagraph (C) under a fair valuation
                        method as described below if--

                       (i)    the Company Stock is not readily tradable on an
                              established securities market when distributed, or

                       (ii)   the Company Stock is subject to a trading
                              limitation.

                        A trading limitation is a restriction under a Federal or
                        State securities law or an agreement (not prohibited by
                        paragraph (1)) affecting the Company Stock so that it is
                        not as freely tradable as stock not subject to such
                        restriction.

                        An arrangement involving the Plan that creates a put
                        option must not provide for the issuance of put options
                        other than as provided under this section. The Plan (and
                        the Trust Fund) must not otherwise obligate itself to
                        acquire Company Stock from a particular holder thereof
                        at an indefinite time determined upon the happening of
                        an event such as the death of the holder.

                 (B)    Fair Valuation. Valuations must be made in good faith
                        and based on all relevant factors for determining the
                        fair market value of securities. In the case of a
                        transaction between a Plan and a disqualified person,
                        value must be determined as of the date of the
                        transaction. For all other Plan purposes, value must be
                        determined as of the most recent valuation date under
                        the Plan. An independent appraisal will not in itself
                        be a good faith determination of value in the case of a
                        transaction between the Plan and a disqualified person.
                        However, in other cases, a determination of fair market
                        value based on at least an annual appraisal
                        independently arrived at by a person who customarily
                        makes such appraisals and who is independent of any
                        party to the transaction will be deemed to be a good
                        faith determination of value. Company Stock not readily
                        tradable on an established securities market shall be
                        valued by an independent appraiser meeting requirements
                        similar to the requirements of the regulations
                        prescribed under Code section 170(a)(l).

                        For purposes of this Plan, the term "disqualified
                        person" means a person who is a fiduciary, a person
                        providing services to the Plan, an Employer any of whose
                        Employees are covered by the Plan, an employee
                        organization any of whose members are covered by the
                        Plan, an owner, direct or indirect, of 50 percent or
                        more of the total combined voting power of all classes
                        of voting stock, or an officer, director, 10 percent or
                        more shareholder, or a Highly Compensated Employee.

                 (C)    The Put Option. The put option must be exercisable only
                        by a Participant, by the Participant's donees, or by a
                        person (including an estate or its distributee) to whom
                        the Company Stock passes by reason of a Participant's
                        death. For the purpose of this section, the term
                        "Participant" means a Participant and the Beneficiaries
                        of the Participant.) The put option must permit a
                        Participant to put the Company Stock to the Employer.
                        Under no circumstances may the put option bind the
                        Plan. However, the put option shall grant the Plan an
                        option to assume the rights and obligations of the
                        Employer at the time that the put option is exercised.

                        If it is known at the time the Common Stock is acquired
                        through a loan that Federal or State law will be
                        violated by the Employer's honoring such put option, the
                        put option must permit the Company Stock to be put, in a
                        manner consistent with such law, to a third party (e.g.,
                        an affiliate of the Employer or a shareholder other than
                        the Plan) that has substantial net worth at the time the
                        loan is made and whose net worth is reasonably expected
                        to remain substantial.

                 (D)    Duration of the Put Option. The put option shall
                        commence as of the day following the date the Company
                        Stock is distributed to the Participant and end 60 days
                        thereafter. If the option is not exercised within such
                        60-day period, an additional 60-day option shall
                        commence on the first day of the fifth month of the
                        Plan Year next following the date the Company Stock was
                        distributed to the Participant (or such other 60-day
                        period as provided in the regulations). However, in the
                        case of Company Stock that is publicly traded without
                        restrictions when distributed but ceases to be so
                        traded within either of the 60-day periods described
                        above after distribution, the Employer must notify each
                        holder of such Company Stock in writing on or before
                        the tenth day after the date the Company Stock ceases
                        to be so traded that for the remainder of the
                        applicable 60-day period the Company Stock is subject
                        to the put option. The number of days between the tenth
                        day and the date on which notice is actually given, if
                        later than the tenth day, must be added to the duration
                        of the put option. The notice must inform distributees
                        of the terms of the put options that they are to hold.
                        The terms must satisfy the requirements of this
                        paragraph.

                        The period during which a put option is exercisable does
                        not include any time when a distributee is unable to
                        exercise it because the party bound by the put option is
                        prohibited from honoring it by applicable Federal or
                        State law.

                 (E)    Exercise of the Option and Exercise Price. The holder of
                        the put option shall notify the Employer in writing that
                        the option is being exercised. The notice shall state
                        the name and address of the holder and the number of
                        shares to be sold. The exercise price of the option is
                        the fair value of the Company Stock determined in
                        accordance with subparagraph (B). Payment under a put
                        option must not be restricted by the provisions of a
                        loan or any other arrangement, including the terms of
                        the Employer's articles of incorporation, unless so
                        required by applicable state law.

                 (F)    Payment for Total Distribution. Payment under the put
                        option involving a "Total Distribution" shall be paid in
                        substantially equal monthly, quarterly, semiannual or
                        annual installments over a period certain beginning not
                        later than 30 days after the exercise of the put option
                        and not extending beyond five years. Adequate security
                        shall be provided and a reasonable interest rate
                        charged.

                        A Total Distribution means a distribution to a
                        Participant within one taxable year of the entire vested
                        amount of his or her Accounts in the Plan.

                 (G)    Payment for Installment Distributions. The amount to be
                        paid under the put option involving installment
                        distributions must be paid not later than 30 days after
                        the exercise of the put option."

It Is Further Resolved that the appropriate officers of the Sponsor are
authorized to execute whatever additional documents, and to take whatever
actions, are necessary or advisable to clarify and implement the foregoing
revision and to satisfy applicable legal requirements.

                          * * * * * * * * * * * * * * *

PCS Administration (USA), Inc. adopted the foregoing amendment on the 1st day of
January, 2000.

                                             PCS Administration (USA), Inc.


                                             By:   /s/ James H. Heppel
                                                   ----------------------------
                                                   VP Human Resources
                                                   ----------------------------