Exhibit 10(aa)
POTASH CORPORATION OF SASKATCHEWAN INC.
AMENDMENT TO THE AGREEMENT
     WHEREAS, the Potash Corporation of Saskatchewan Inc., a corporation
organized under the laws of Canada (the “Corporation”), entered into an
agreement (the “Agreement”) that was most recently amended and restated as of
August 2, 1996 and subsequently amended on May 17, 2000, November 5, 2002 and
February 23, 2009, with Garth W. Moore of the City of Saskatoon, in the province
of Saskatchewan, an executive of the Corporation (the “Executive”), for the
provision by the Corporation to the Executive of a supplemental retirement
benefit;
     WHEREAS, the Corporation and the Executive now desire to amend the
Agreement to incorporate a new formula for computing the Executive’s benefit
under the Agreement with respect to services performed on and after January 1,
2011;
     NOW, THEREFORE, the Agreement is hereby amended, effective as of January 1,
2011, as follows (the “Amendment”):
     1. The second sentence of paragraph 1 of the Agreement (the definition of
“Earnings”) is hereby amended (taking into account the provisions of this
Amendment set forth below) by substituting the phrase “for purposes of sections
(b)(ii) and (b)(iii) of paragraph 4 of this Agreement” therein for the phrase
“for purposes of section (b)(ii) of paragraph 4 of this Agreement”.
     2. Paragraph 4 of the Agreement is hereby amended in its entirety to read
as follows:

  “4.   The annual supplemental retirement benefit payable under this Agreement,
if any, shall be calculated as of the date of the Executive’s termination of
employment (or death, if earlier) as follows:

  (a)   5% of the Executive’s average 3 highest calendar years’ Earnings,

      multiplied by

      the Executive’s years (including partial years calculated to the last full
month completed) of Continuous Service completed before July 1, 2009 up to a
maximum of 10 years;

      PLUS

  (b)   the sum of (i), (ii) and (iii), where:

  (i)   is equal to 2% of the Executive’s average 3 highest calendar years’
Earnings,

 

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      multiplied by

      the Executive’s years (including partial years calculated to the last full
month completed) of Continuous Service in excess of 25 years to a maximum of 10
additional years, to the extent that such Continuous Service was completed
before July 1, 2009;     (ii)   is equal to 2% of the Executive’s average
Earnings for the 3 consecutive calendar years during which the Executive’s
Earnings were the highest,

      multiplied by

      the Executive’s years (including partial years calculated to the last full
month completed) of Continuous Service in excess of 25 years to a maximum of 10
additional years, provided that (A) such Continuous Service was completed on and
after July 1, 2009 but before January 1, 2011, and (B) the sum of the years of
Continuous Service taken into account under section (b)(i) and this section
(b)(ii) does not exceed 10; and     (iii)   is equal to 1.5% of the Executive’s
average Earnings for the 3 consecutive calendar years during which the
Executive’s Earnings were the highest,

      multiplied by

      the Executive’s years (including partial years calculated to the last full
month completed) of Continuous Service in excess of 25 years to a maximum of 10
additional years, provided that (A) such Continuous Service was completed on and
after January 1, 2011, and (B) the sum of the years of Continuous Service taken
into account under sections (b)(i) and (b)(ii) and this section (b)(iii) does
not exceed 10;

      MINUS

  (c)   the annual retirement benefit which can be provided with the sum of
(i) the balance of the Executive’s account under the Pension Plan attributable
to employee contributions made to such plan by the Executive as of December 31,
2010, adjusted on and after January 1, 2011 for its allocable share of earnings
through the date of the Executive’s termination of employment or death, as the
case

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      may be, and (ii) the Executive’s account balance under the Pension Plan
attributable to employer contributions made to the Pension Plan by the
Corporation and/or its subsidiaries or affiliates on behalf of the Executive
(and earnings thereon through the date of the Executive’s termination of
employment or death, as the case may be).”

     3. In all other respects the Agreement remains unchanged.
IN WITNESS WHEREOF the Corporation has executed this Amendment by its duly
authorized officers on its behalf and the Executive has executed this Amendment
29th day of December, 2010.

            POTASH CORPORATION OF
SASKATCHEWAN INC.
      By:   /s/ Barbara Jane Irwin               Garth W. Moore       /s/ Garth
W. Moore    

SIGNED SEALED AND DELIVERED in the presence of:

      Lee M. Knafelc
 
Name of Witness
   
 
    /s/ Lee M. Knafelc
 
Signature of Witness
   

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