POTASH CORPORATION OF SASKATCHEWAN INC.
                   STOCK OPTION PLAN -- OFFICERS AND EMPLOYEES


1.    Purpose of Plan

      Potash Corporation of Saskatchewan Inc. (the "Corporation") by resolution
      of its Board of Directors (the "Board") has established this Plan to
      encourage officers and employees of the Corporation and its subsidiaries
      to promote the growth and profitability of the Corporation by providing
      them with the opportunity through options to acquire Common Shares of the
      Corporation ("Common Shares").

2.    Administration

      This Plan shall be administered by the Board.

3.    Grant of Options

      From time to time the Board may designate individual officers and
      employees of the Corporation and its subsidiaries eligible to be granted
      options to purchase Common Shares and the number of Common Shares which
      each such person will be granted an option to purchase; provided that the
      aggregate number of Common Shares subject to such options may not exceed
      the number provided for in paragraph 4 of this Plan.

4.    Shares Subject to Option

      The aggregate number of Common Shares issuable after February 3, 1998
      pursuant to options under this Plan may not exceed 6,926,125 shares. The
      number of Common Shares issuable pursuant to options under this Plan shall
      be subject to adjustment under paragraphs 8 and 9.

      The aggregate number of Common Shares in respect of which options have
      been granted to any one person and which remain outstanding shall not at
      any time exceed 5% of the number of issued and outstanding Common Shares
      (on a non-diluted basis) at that time.

      If any option granted under this Plan, or any portion thereof, expires or
      terminates for any reason without having been exercised in full, the
      Common Shares with respect to which such option has not been exercised
      shall again be available for further options under this Plan.

5.    Option Price

      The option price under this Plan to any optionee shall be fixed by the
      Board when the option is granted and shall be not less than the fair
      market value of the Common Shares at such time which, for optionees
      resident in the United States and any other optionees designated by the
      Board, shall be deemed to be the closing price per share of the Common
      Shares on the New York Stock Exchange on the last trading day immediately
      preceding the day the option is granted and, for all other optionees,
      shall be deemed to be the closing price per share of the Common Shares on
      The Toronto Stock Exchange on the last trading day immediately preceding
      the day the option is granted; provided that, in either case, if the
      Common Shares did not trade on such exchange on such day the option price
      shall be the closing price per share on such exchange on the last day on
      which the Common Shares traded on such exchange prior to the day the
      option is granted.

6.    Terms of Option

      The period during which an option is exercisable may not exceed 10 years
      from the date the option is granted, and the option agreement may contain
      provisions limiting the number of Common Shares with respect to which the
      option may be exercised in any one year. Each option agreement shall
      contain provisions to the effect that:

      a.  if the employment of an optionee as an officer or employee of the
          Corporation or a subsidiary terminates, by reason of his or her death,
          or if an optionee who is a retiree pursuant to clause b below dies,
          the legal personal representatives of the optionee will be entitled to
          exercise any unexercised options, including such options that may vest
          after the date of death, during the period ending at the end of the
          twelfth calendar month following the calendar month in which the
          optionee dies, failing which exercise the options terminate;

      b.  subject to the terms of clause a above, if the employment of an
          optionee as an officer or employee of the Corporation or a subsidiary
          terminates, by reason of retirement in accordance with the then
          prevailing retirement policy of the Corporation or subsidiary, the
          optionee will be entitled to exercise any unexercised options,
          including such options as may vest after the date of retirement, until
          the expiry date of such options or the date on which such options are
          otherwise terminated in accordance with the provisions of this Plan,
          failing which exercise the options terminate. Notwithstanding the
          foregoing, the Board may, at the time of grant, prescribe such shorter
          period of time for exercise following retirement as it deems
          appropriate;

      c.  if the employment of an optionee as an officer or employee of the
          Corporation or a subsidiary terminates, for any reason other than as
          provided in the preceding clauses a or b, the optionee will be
          entitled to exercise any unexercised options, to the extent
          exercisable at the date of such event, during the period ending at the
          end of the calendar month immediately following the calendar month in
          which the event occurs, failing which exercise the options terminate.

          For greater certainty and for these purposes, an optionee's employment
          with the Corporation or a subsidiary shall be considered to have
          terminated effective on the last day of the optionee's actual and
          active employment with the Corporation or subsidiary whether such day
          is selected by agreement with the optionee or unilaterally by the
          Corporation or subsidiary and whether with or without advance notice
          to the optionee. For the avoidance of doubt, no period of notice that
          is given or ought to have been given under applicable law in respect
          of such termination of employment will be utilized in determining an
          optionee's entitlement under the Plan; and

      d.  each option is personal to the optionee and is not assignable, except
          (i) as provided in the preceding clause a, and (ii) at the election of
          the Board, an option may be assignable to the spouse, children and
          grandchildren of the original optionee and to a trust, partnership or
          limited liability company, the entire beneficial interest of which is
          held by one or more of the foregoing.

      Nothing contained in the preceding clauses a, b, or c shall extend the
      period during which an option may be exercised beyond its stipulated
      expiry date or the date on which it is otherwise terminated in accordance
      with the provisions of this Plan.

      If an option is assigned pursuant to the preceding subclause (ii) of
      clause d, the references in the preceding clauses a, b and c to the
      termination of employment or death of an optionee shall not relate to the
      assignee of an option but shall relate to the original optionee. In the
      event of such assignment, legal personal representatives of the original
      optionee shall not be entitled to exercise the assigned option, but the
      assignee of the option or the legal personal representatives of the
      assignee may exercise the option during the applicable specified period.

7.    Exercise of Options

      Subject to the provisions of this Plan, an option may be exercised from
      time to time by delivering to the Corporation at its registered office a
      written notice of exercise specifying the number of shares with respect to
      which the option is being exercised and accompanied by payment in cash or
      certified cheque in full of the purchase price of the shares then being
      purchased.

8.    Adjustments

      Appropriate adjustments to the authorized limits set forth in paragraph 4,
      in the number, class and/or type of shares optioned and in the option
      price per share, both as to options granted or to be granted, may be made
      by the Board in its discretion to give effect to adjustments in the number
      of Common Shares which result from subdivisions, consolidations or
      reclassifications of the Common Shares, the payment of share dividends by
      the Corporation, the reconstruction, reorganization or recapitalization of
      the Corporation or other relevant changes in the capital of the
      Corporation. If the Corporation sells all or substantially all of its
      assets as an entirety or substantially as an entirety, options under this
      Plan may be exercised, in whole or in part, at any time up to and
      including (but not after) a date 30 days following the date of completion
      of such sales or prior to the close of business on the date the option
      expires, whichever is earlier.

9.    Mergers

      If the Corporation proposes to amalgamate or merge with another body
      corporate, the Corporation shall give written notice thereof to optionees
      in sufficient time to enable them to exercise outstanding options, to the
      extent they are otherwise exercisable by their terms, prior to the
      effective date of such amalgamation or merger if they so elect. The
      Corporation shall use its best efforts to provide for the reservation and
      issuance by the amalgamated or continuing corporation of an appropriate
      number of shares, with appropriate adjustments, so as to give effect to
      the continuance of the options to the extent reasonably practicable. In
      the event that the Board determines in good faith that such continuance is
      not in the circumstances practicable, it may upon 30 days' notice to
      optionees terminate the options.

10.   Change of Control

      If a "change of control" of the Corporation occurs, each then outstanding
      option granted under this Plan may be exercised, in whole or in part, even
      if such option is not otherwise exercisable by its terms. For purposes of
      this paragraph 10, a change of control of the Corporation shall be deemed
      to have occurred if:

      a.  within any period of two consecutive years, individuals who at the
          beginning of such period constituted the Board and any new directors
          whose appointment by the Board or nomination for election by
          shareholders of the Corporation was approved by a vote of at least a
          majority of the directors then still in office who either were
          directors at the beginning of the period or whose appointment or
          nomination for election was previously so approved, cease for any
          reason to constitute a majority of the Board;

      b.  there occurs an amalgamation, merger, consolidation, wind-up,
          reorganization or restructuring of the Corporation with or into any
          other entity, or a similar event or series of such events, other than
          any such event or series of events which results in securities of the
          surviving or consolidated corporation representing 50% or more of the
          combined voting power of the surviving or consolidated corporation's
          then outstanding securities entitled to vote in the election of
          directors of the surviving or consolidated corporation being
          beneficially owned, directly or indirectly, by the persons who were
          the holders of the Corporation's outstanding securities entitled to
          vote in the election of directors of the Corporation prior to such
          event or series of events in substantially the same proportions as
          their ownership immediately prior to such event of the Corporation's
          then outstanding securities entitled to vote in the election of
          directors of the Corporation;

      c.  50% or more of the fixed assets (based on book value as shown on the
          most recent available audited annual or unaudited quarterly
          consolidated financial statements) of the Corporation are sold or
          otherwise disposed of (by liquidation, dissolution, dividend or
          otherwise) in one transaction or series of transactions within any
          twelve month period;

      d.  any party, including persons acting jointly or in concert with that
          party, becomes (through a take-over bid or otherwise) the beneficial
          owner, directly or indirectly, of securities of the Corporation
          representing 20% or more of the combined voting power of the
          Corporation's then outstanding securities entitled to vote in the
          election of directors of the Corporation, unless in any particular
          situation the Board determines in advance of such event that such
          event shall not constitute a change of control; or

      e.  the Board approves and/or recommends that shareholders accept, approve
          or adopt any transaction that would constitute a change of control
          under clause b, c or d above.

11.   Amendment or Discontinuance of this Plan

      The Board may amend or discontinue the Plan at any time but, subject to
      paragraphs 8, 9, and 10, no such amendment may increase the aggregate
      maximum number of shares that may be subject to option under this Plan,
      change the manner of determining the minimum option price, extend the
      option period under any option beyond 10 years or, without the consent of
      the holder of the option, alter or impair any option previously granted to
      an optionee under this Plan. Amendments to the Plan require pre-clearance
      of The Toronto Stock Exchange.

12.   Evidence of Options

      Each option granted under this Plan shall be embodied in a written option
      agreement between the Corporation and the optionee which shall give effect
      to the provisions of this Plan.