Exhibit 10(ff)
December 31, 2010
Mr. William J. Doyle
Re: Section 409A Compliance
Dear Bill:
     As you may know, Section 409A of the Internal Revenue Code, along with the
rules, regulations and guidance promulgated thereunder by the U.S. Department of
the Treasury or the U.S. Internal Revenue Service (collectively,
“Section 409A”), has imposed rules relating to the taxation of deferred
compensation. The rules cover all non-qualified deferred compensation plans and
arrangements, including certain amounts to which you are, or may become,
entitled under the Agreement among Potash Corporation of Saskatchewan Sales
Limited (“PCS Sales”), Potash Corporation of Saskatchewan Inc. (“PCS”), and
William J. Doyle (the “Executive”), dated as of December 30, 1994 (the
“Agreement”). A failure to comply with the requirements under Section 409A may
result in adverse tax penalties to you, including accelerated taxation of all
amounts subject to Section 409A, a 20% income tax penalty, and possible interest
penalties on such amounts (in some cases, even if you do not actually receive
the amounts).
     Notwithstanding anything in the Agreement to the contrary, the Agreement is
hereby amended as follows:

1.   Compliance with Section 409A. The parties intend that any amounts payable
under the Agreement, and PCS Sales’, PCS’, and the Executive’s exercise of
authority or discretion under the Agreement comply with the provisions of
Section 409A so as not to subject the Executive to the payment of the additional
tax, interest and any tax penalty which may be imposed under Section 409A. In
furtherance thereof, to the extent that any provision of the Agreement would
result in the Executive being subject to payment of the additional tax, interest
and tax penalty under Section 409A, the parties agree to amend the Agreement if
permitted under Section 409A in a manner which does not impose any additional
taxes, interest or penalties on the Executive in order to bring the Agreement
into compliance with Section 409A, without materially changing the economic
value of the arrangements under the Agreement to any of the parties, and
thereafter the parties will interpret its provisions in a manner that complies
with Section 409A. Notwithstanding the foregoing, no particular tax result for
the Executive with respect to any income recognized by the Executive in
connection with the Agreement is guaranteed.

2.   Delay for Specified Employees. Notwithstanding any provisions of the
Agreement to the contrary, if the Executive is a “specified employee” (within
the meaning of Section 409A and determined pursuant to any policies adopted by
PCS Sales or PCS, as the case may be, consistent with Section 409A) at the time
of the Executive’s separation from service and if any portion of the payments or
benefits to be received by the Executive upon separation from service would be
considered deferred compensation under Section 409A and cannot be paid or
provided to the Executive without the Executive incurring taxes, interest or
penalties under Section 409A, amounts that would otherwise be payable

 

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    pursuant to the Agreement and benefits that would otherwise be provided
pursuant to the Agreement, in each case, during the six-month period immediately
following the Executive’s separation from service will instead be paid or made
available on the earlier of (i) the first business day of the seventh month
following the date of the Executive’s separation from service or (ii) the
Executive’s death.

3.   Expense Reimbursement; In-Kind Benefits. With respect to any amount of
expenses eligible for reimbursement or the provision of any in-kind benefits
under the Agreement, to the extent such payment or benefit would be considered
deferred compensation under Section 409A or is required to be included in the
Executive’s gross income for U.S. federal income tax purposes, such expenses
(including, without limitation, expenses associated with in-kind benefits) will
be reimbursed by PCS Sales or PCS, as the case may be, in accordance with the
terms of the Agreement, but in no event later than December 31st of the year
following the year in which the Executive incurs the related expenses. In no
event will the reimbursements or in-kind benefits to be provided by PCS Sales or
PCS, as the case may be, in one taxable year affect the amount of reimbursements
or in-kind benefits to be provided in any other taxable year, nor will the
Executive’s right to reimbursement or in-kind benefits be subject to liquidation
or exchange for another benefit.

4.   Additional Payments. If, under any provision of the Agreement, the
Executive becomes entitled to a payment to reimburse the Executive for all or a
designated portion of the U.S. federal, state, local, or foreign taxes imposed
upon the Executive as a result of compensation paid to the Executive by PCS
Sales or PCS, as the case may be, or the amount of any additional taxes imposed
upon the Executive by reason of PCS Sales’ or PCS’, as the case may be, payment
of the initial tax, such payment will be made to the Executive in accordance
with the Agreement, but in no event later than the end of the taxable year
following the taxable year in which the Executive remits the related taxes to
the taxing authority.

5.   Separate Payments. Each payment under the Agreement is intended to be a
“separate payment” and not of a series of payments for purposes of Section 409A.

6.   Separation from Service. A termination of employment will not be deemed to
have occurred for purposes of any provision of the Agreement providing for the
payment of any amounts or benefits subject to Section 409A upon or following a
termination of employment unless such termination is also a “separation from
service” (within the meaning of Section 409A), and notwithstanding anything
contained in the Agreement to the contrary, the date on which such separation
from service takes place will be the termination date for such purposes.

7.   Deferral Elections. Notwithstanding any provisions of the Agreement to the
contrary, the severance payment described in Section 2.a) of the Agreement will
be paid in a lump sum, and in no event may PCS Sales, PCS, or the Executive
voluntarily elect to defer any payments or benefits provided pursuant to the
Agreement that are or would be subject to Section 409A, other than as provided
by Section 409A.

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8.   Excise Tax. Clause 4 of the Agreement (entitled Excise Tax) is amended and
restated in its entirety as follows:

  “a)   Notwithstanding any other provisions in this Agreement, in the event
that any payment or benefit received or to be received by the Executive
(including, without limitation, any payment or benefit received in connection
with a Change-in-Control or the termination of the Executive’s employment,
whether pursuant to the terms of this Agreement or any other plan, program,
arrangement or agreement) (all such payments and benefits, together the “Total
Payments”) would be subject (in whole or part), to any excise tax imposed under
Section 4999 of the U.S. Internal Revenue Code of 1986, as amended (the “Code”),
or any successor provision thereto (the “Excise Tax”), then, after taking into
account any reduction in the Total Payments provided by reason of Section 280G
of the Code in such other plan, program, arrangement or agreement, the
Executive’s payments and/or benefits under this Agreement will be reduced to the
extent necessary so that no portion of the Total Payments is subject to the
Excise Tax (but in no event to less than zero), in the following order:

  i)   any cash severance amount derived based upon the Executive’s Base Salary,
Average Bonus, or Target Bonus, as described in clauses 2.a).i) — 2.a).iii);    
ii)   any cash severance amount derived based upon the Long-Term Incentive Plan,
as described in clause 2.a).iv);     iii)   any stock option vesting
acceleration or related payments, as described in clause 3;     iv)   any
financial or outplacement counseling reimbursement, as described in clause 2.e);
    v)   any retirement benefits, as described in clause 2.c); and     vi)   any
group insurance coverage reimbursement, as described in clause 2.d)

      (the payments and benefits set forth in the preceding clauses 4.a).i) —
4.a).vi), together, the “Potential Payments”); provided, however, that the
Potential Payments shall only be reduced if (A) the net amount of such Total
Payments, as so reduced (and after subtracting the net amount of federal, state,
local and foreign income taxes on such reduced Total Payments and after taking
into account the phase out of itemized deductions and personal exemptions
attributable to such reduced Total Payments) is greater than or equal to (B) the
net amount of such Total Payments without such reduction (but after subtracting
the net amount of federal, state, local and foreign income taxes on such Total
Payments and the amount of Excise Tax to which the Executive would be subject in
respect of such unreduced Total Payments and after taking into account the phase
out of itemized deductions and personal exemptions attributable to such
unreduced Total Payments.

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  b)   For purposes of determining whether and the extent to which the Total
Payments will be subject to the Excise Tax: (i) no portion of the Total Payments
the receipt or enjoyment of which the Executive shall have waived at such time
and in such manner as not to constitute a “payment” within the meaning of
Section 280G(b) of the Code shall be taken into account; (ii) no portion of the
Total Payments shall be taken into account which, in the opinion of tax counsel
(“Tax Counsel”) reasonably acceptable to the Executive and selected by the
accounting firm which was, immediately prior to the Change-in-Control, PCS’
independent auditor (the “Auditor”), does not constitute a “parachute payment”
within the meaning of Section 280G(b)(2) of the Code (including, without
limitation, by reason of Section 280G(b)(4)(A) of the Code) and, in calculating
the Excise Tax, no portion of such Total Payments shall be taken into account
which, in the opinion of Tax Counsel, constitutes reasonable compensation for
services actually rendered, within the meaning of Section 280G(b)(4)(B) of the
Code, in excess of the “base amount” (as set forth in Section 280G(b)(3) of the
Code) that is allocable to such reasonable compensation; and (iii) the value of
any non-cash benefit or any deferred payment or benefit included in the Total
Payments shall be determined by the Auditor in accordance with the principles of
Sections 280G(d)(3) and (4) of the Code.     c)   At the time that payments are
made under this Agreement, the Executive shall be provided with a written
statement setting forth the manner in which such payments were calculated and
the basis for such calculations, including, without limitation, any opinions or
other advice received from Tax Counsel, the Auditor, or other advisors or
consultants (and any such opinions or advice which are in writing shall be
attached to the statement). If the Executive objects to the calculations, the
Executive shall be paid such portion of the Potential Payments (up to 100%
thereof) as the Executive determines is necessary to result in the proper
application of this clause 4. All determinations required by this clause 4 (or
requested by any of the parties in connection with this clause 4) shall be at
the expense of PCS. The fact that the Executive’s right to payments or benefits
may be reduced by reason of the limitations contained in this clause 4 shall not
of itself limit or otherwise affect any other rights of the Executive under this
Agreement.”

This letter agreement will constitute an amendment to the Agreement. Other than
as provided herein, all other terms and conditions of the Agreement will
continue to be in full force and effect.
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In witness whereof, the parties have executed this amendment to the Agreement as
of the date first written above.

            PCS Sales (Canada) Inc. (as successor to
Potash Corporation of Saskatchewan Sales
Limited)
      By:   /s/ Bob Kirkpatrick     Name:                 Potash Corporation of
Saskatchewan Inc.
      By:   /s/ John W. Estey     Name:               /s/ William J. Doyle    
William J. Doyle