Ownership Submission
FORM 4
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
DUNN E PAUL JR
  2. Issuer Name and Ticker or Trading Symbol
MOSAIC CO [MOS]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director _____ 10% Owner
__X__ Officer (give title below) _____ Other (specify below)
Vice President and Treasurer
(Last)
(First)
(Middle)
12800 WHITEWATER DRIVE, SUITE 200
3. Date of Earliest Transaction (Month/Day/Year)
10/22/2004
(Street)

MINNETONKA, MN 55343
4. If Amendment, Date Original Filed(Month/Day/Year)
6. Individual or Joint/Group Filing(Check Applicable Line)
_X_ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)
2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code
(Instr. 8)
4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)
5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)
6. Ownership Form: Direct (D) or Indirect (I)
(Instr. 4)
7. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V Amount (A) or (D) Price
Common Stock 10/22/2004   A   16,615 A (1) 16,615 D  

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 3)
2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 4. Transaction Code
(Instr. 8)
5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4, and 5)
6. Date Exercisable and Expiration Date
(Month/Day/Year)
7. Title and Amount of Underlying Securities
(Instr. 3 and 4)
8. Price of Derivative Security
(Instr. 5)
9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 4)
10. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 4)
11. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares
Stock Option (right to buy) $ 34.875 10/22/2004   A   12,500   10/22/2004 05/12/2008 Common Stock 12,500 $ 34.875 (2) 12,500 D  
Stock Option (right to buy) $ 30.656 10/22/2004   A   3,300   10/22/2004 06/18/2008 Common Stock 3,300 $ 30.656 (2) 3,300 D  
Stock Option (right to buy) $ 22.6562 10/22/2004   A   16,600   10/22/2004 04/27/2009 Common Stock 16,600 $ 22.6562 (2) 16,600 D  
Stock Option (right to buy) $ 15.0312 10/22/2004   A   27,000   10/22/2004 02/22/2010 Common Stock 27,000 $ 15.0312 (2) 27,000 D  
Stock Option (right to buy) $ 15.0625 10/22/2004   A   16,700   10/22/2004 03/30/2010 Common Stock 16,700 $ 15.0625 (2) 16,700 D  
Stock Option (right to buy) $ 13.55 10/22/2004   A   45,000   10/22/2004 02/28/2011 Common Stock 45,000 $ 13.55 (2) 45,000 D  
Stock Option (right to buy) $ 10.71 10/22/2004   A   50,000   10/22/2004 11/05/2011 Common Stock 50,000 $ 10.71 (2) 50,000 D  
Stock Option (right to buy) $ 10.76 10/22/2004   A   35,000   10/22/2004 01/02/2013 Common Stock 35,000 $ 10.76 (2) 35,000 D  
Stock Option (right to buy) $ 10.19 10/22/2004   A   35,000   10/22/2004 01/02/2014 Common Stock 35,000 $ 10.19 (2) 35,000 D  

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
DUNN E PAUL JR
12800 WHITEWATER DRIVE
SUITE 200
MINNETONKA, MN 55343
      Vice President and Treasurer  

Signatures

 s/ Richard L. Mack   10/26/2004
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) Received in exchange for 20,788 shares of IMC Global Inc. common stock with merger of IMC Global (the "Merger"). On the effective date of the Merger, the closing price of IMC Global's common stock was $15.00 per share.
(2) Received in the Merger in exchange for a stock option to acquire the same number of IMC Global common stock at the same price per share.

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