POTASH CORPORATION OF SASKATCHEWAN INC.
                         STOCK OPTION PLAN -- DIRECTORS


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 directors of the Corporation 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 directors of the
      Corporation 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 January 24, 1995
      pursuant to options under this Plan may not exceed 456,000 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 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. 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 an optionee ceases to be a director of the Corporation by reason of
          his or her death or 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 an optionee ceases to be a
          director of the Corporation by reason of retirement in accordance with
          the then prevailing retirement policy of the Corporation, 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;

      c.  if an optionee ceases to be a director of the Corporation 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; 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 ceasing to
      be a director 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 this 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.