-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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<SEC-DOCUMENT>0001179110-05-017552.txt : 20050906
<SEC-HEADER>0001179110-05-017552.hdr.sgml : 20050905
<ACCEPTANCE-DATETIME>20050906170605
ACCESSION NUMBER:		0001179110-05-017552
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20050901
FILED AS OF DATE:		20050906
DATE AS OF CHANGE:		20050906

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			TERRA NITROGEN CO L P /DE
		CENTRAL INDEX KEY:			0000879575
		STANDARD INDUSTRIAL CLASSIFICATION:	AGRICULTURE CHEMICALS [2870]
		IRS NUMBER:				731389684
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		TERRA CENTRE 600 FOURTH STREET
		STREET 2:		PO BOX 6000
		CITY:			SIOUX CITY
		STATE:			IA
		ZIP:			51102-6000
		BUSINESS PHONE:		7122771340

	MAIL ADDRESS:	
		STREET 1:		TERRA CENTER 600 FOURTH STREET
		STREET 2:		PO BOX 6000
		CITY:			SIOUX CITY
		STATE:			IA
		ZIP:			51102-6000

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Terra Nitrogen GP Inc.
		CENTRAL INDEX KEY:			0001337605
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	033-43007
		FILM NUMBER:		051070971

	BUSINESS ADDRESS:	
		STREET 1:		600 FOURTH STREET
		STREET 2:		P.O. BOX 6000
		CITY:			SIOUX CITY
		STATE:			IA
		ZIP:			51102-6000
		BUSINESS PHONE:		712-277-1350

	MAIL ADDRESS:	
		STREET 1:		600 FOURTH STREET
		STREET 2:		P.O. BOX 6000
		CITY:			SIOUX CITY
		STATE:			IA
		ZIP:			51102-6000
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 3 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2005-09-01</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000879575</issuerCik>
        <issuerName>TERRA NITROGEN CO L P /DE</issuerName>
        <issuerTradingSymbol>TNH</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001337605</rptOwnerCik>
            <rptOwnerName>Terra Nitrogen GP Inc.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>600 FOURTH STREET</rptOwnerStreet1>
            <rptOwnerStreet2>P.O. BOX 6000</rptOwnerStreet2>
            <rptOwnerCity>SIOUX CITY</rptOwnerCity>
            <rptOwnerState>IA</rptOwnerState>
            <rptOwnerZipCode>51102-6000</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>General Partner</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Units</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">On September 1, 2005, the issuer completed a restructuring of its general partner interest whereby the reporting person succeeded as general partner of the issuer. Additional information on the issuer's restructuring is setforth in the issuer's Form 8-K filed in connection with the restructuring as of a recent date hereof.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Mark A. Kalafut - Vice President, General Counsel and Corporate Secretary</signatureName>
        <signatureDate>2005-09-06</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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