SUMMARY

This summary highlights selected information from this proxy statement/prospectus. You are urged to read carefully the entire proxy statement/prospectus and the other documents referred to in this proxy statement/prospectus because the information in this section does not provide all the information that might be important to you with respect to the merger agreement, the mergers and the other matters being considered at the Rentech Nitrogen special meeting. See “Where You Can Find More Information.”

The Parties

CVR Partners, LP

CVR Partners is a Delaware limited partnership formed by CVR Energy, Inc. (“CVR Energy”) to own, operate and grow its nitrogen fertilizer business. Strategically located adjacent to CVR Energy’s affiliated refinery in Coffeyville, Kansas, CVR Partners’ nitrogen fertilizer manufacturing facility is the only operation in North America that utilizes a petroleum coke, or pet coke, gasification process to produce nitrogen fertilizer.

The address of CVR Partners’ and CVR Partners GP’s principal executive offices is 2277 Plaza Drive, Suite 500, Sugar Land, Texas 77479, and its telephone number is (281) 207-3200. Additional information about CVR Partners and its subsidiaries is included in the documents incorporated by reference into this proxy statement/prospectus. See “Where You Can Find More Information.”

Rentech Nitrogen Partners, L.P.

Rentech Nitrogen is a Delaware limited partnership formed in July 2011 by Rentech to own, operate and expand its fertilizer business. Rentech Nitrogen owns and operates two fertilizer facilities: the East Dubuque Facility and the Pasadena Facility. The East Dubuque Facility produces primarily ammonia and urea ammonium nitrate solution, or UAN, using natural gas as the facility’s primary feedstock. The Pasadena Facility produces ammonium sulfate, ammonium thiosulfate and sulfuric acid, using ammonia and sulfur as the facility’s primary feedstocks. It is a condition to the completion of the mergers that Rentech Nitrogen sell or spin off the Pasadena Facility and its related business, in each case subject to certain terms specified in the merger agreement and, if applicable, the separation agreement.

Rentech Nitrogen’s principal executive offices are located at 10877 Wilshire Boulevard, 10th Floor, Los Angeles, California 90024, and its telephone number is (310) 571-9800. Additional information about Rentech Nitrogen and its subsidiaries is included in the documents incorporated by reference into this proxy statement/prospectus. See “Where You Can Find More Information.”

Lux Merger Sub 1 LLC

Merger Sub 1 is a Delaware limited liability company and wholly owned subsidiary of CVR Partners. Merger Sub 1 was created for purposes of the Rentech Nitrogen GP merger and has not carried on any activities to date, other than activities incidental to its formation or undertaken in connection with the transactions contemplated by the merger agreement.

Lux Merger Sub 2 LLC

Merger Sub 2 is a Delaware limited liability company and wholly owned subsidiary of CVR Partners. Merger Sub 2 was created for purposes of the Rentech Nitrogen merger and has not carried on any activities to date, other than activities incidental to its formation or undertaken in connection with the transactions contemplated by the merger agreement.

The Mergers

The merger agreement provides, subject to the terms and conditions therein and in accordance with Delaware law, for the merger of Merger Sub 1 with and into Rentech Nitrogen GP and the merger of Merger Sub 2 with and into Rentech Nitrogen. Rentech Nitrogen GP and Rentech Nitrogen will survive the mergers as subsidiaries of CVR Partners.

Merger Consideration

The merger agreement provides that, at the effective time, each eligible Rentech Nitrogen common unit issued and outstanding immediately prior to the effective time will be converted into the right to receive 1.04 CVR Partners common units and $2.57 in cash, without interest. Any Rentech Nitrogen common units that are owned by Rentech Nitrogen or CVR Partners or any of their respective subsidiaries at the effective time (except for certain Rentech Nitrogen common units held by affiliates of CVR Partners that are designated by CVR Partners prior to the effective time to remain outstanding (the “CVR Partners affiliate units”)) will be cancelled without any conversion or payment of consideration in respect thereof.

Treatment of Rentech Nitrogen Phantom Units

Continuing Employees. Immediately prior to the effective time, all outstanding phantom units granted under the Rentech Nitrogen LTIP and held by an employee of Rentech Nitrogen or Rentech Nitrogen GP or one of their subsidiaries (other than the Pasadena subsidiaries) who is a continuing employee will be automatically cancelled and forfeited. At the effective time, CVR Partners will grant a replacement incentive award to each such continuing employee which will be equal in value (determined by reference to the closing price of the units underlying such replacement incentive award on the mergers closing date) to the cancelled and forfeited phantom units. The replacement incentive award will be granted under the CVR Partners LTIP in the form of a “phantom unit” as defined under the CVR Partners LTIP, and will be subject to substantially the same terms and conditions (including, without limitation, applicable vesting and payment timing provisions) as the cancelled and forfeited phantom units. Any then-accumulated distribution equivalents payable upon a subsequent vesting date pursuant to distribution equivalent rights linked to any forfeited Rentech Nitrogen phantom unit will be paid by CVR Partners to the continuing employee upon the vesting of the CVR Partners “phantom unit” corresponding to such forfeited Rentech Nitrogen phantom unit.

Non-Continuing Employees and Rentech Nitrogen Board Members. Each phantom unit granted under the Rentech Nitrogen LTIP and held by (i) an employee who is terminated at the effective time and does not become a continuing employee (including an employee who continues in employment with Rentech following the effective time) or (ii) any member of the Rentech Nitrogen Board, in any case, that is outstanding immediately prior to the effective time will, as of the effective time, automatically and without any action on the part of the holder, vest in full and be cancelled. In consideration therefor, the holder of such phantom unit will be entitled to receive the merger consideration. In addition, any then-accumulated distribution equivalents payable pursuant to distribution equivalent rights with respect to each phantom unit that vests pursuant to these terms will, as of the effective time, automatically and without any action on the part of the holder thereof, vest in full and be paid to the holder thereof in cash.

Rentech Nitrogen Special Meeting; Unitholders Entitled to Vote; Vote Required

Meeting. The Rentech Nitrogen special meeting will be held on                 , 2015, at         a.m., local time, at                 . At the Rentech Nitrogen special meeting, Rentech Nitrogen common unitholders will be asked to vote on the following proposals:

Record Date. Only Rentech Nitrogen common unitholders of record at the opening of business on                 , 2015, the record date for the determination of holders entitled to notice of and to vote at the Rentech Nitrogen special meeting, will be entitled to receive notice of and to vote at the Rentech Nitrogen special meeting. As of the opening of business on the record date of                 , 2015, there were                 Rentech Nitrogen common units outstanding and entitled to vote at the meeting. Each holder of Rentech Nitrogen common units is entitled to one vote for each common unit owned as of the record date.

Required Vote. Approval of the merger proposal requires the affirmative vote of the holders of a majority of the outstanding Rentech Nitrogen common units present in person or by proxy at the Rentech Nitrogen special meeting. Rentech Nitrogen cannot complete the mergers unless its common unitholders approve the merger proposal.

Approval (on an advisory, non-binding basis) of the merger-related compensation proposal requires the affirmative vote of the holders of a majority of the outstanding Rentech Nitrogen common units present in person or by proxy at the Rentech Nitrogen special meeting.

The Rentech Unitholders have entered into the voting and support agreement with CVR Partners, pursuant to which, subject to certain exceptions, each of the Rentech Unitholders has agreed to vote all of the Rentech Nitrogen common units it owns in favor of the merger proposal and to take other actions in furtherance of the mergers. The Rentech Unitholders collectively hold Rentech Nitrogen common units representing approximately 59.7% of the outstanding Rentech Nitrogen common units as of the date of this proxy statement/prospectus, which is a sufficient number of Rentech Nitrogen common units to approve the merger proposal without the affirmative vote of any other Rentech Nitrogen common unitholders. Accordingly, assuming the voting and support obligations are not terminated prior to the Rentech Nitrogen special meeting and the Rentech Nitrogen special meeting is held, approval of the merger proposal at the Rentech Nitrogen special meeting is assured.

Unit Ownership of and Voting by Rentech Nitrogen GP’s Directors and Executive Officers. At the opening of business on the record date for the Rentech Nitrogen special meeting, Rentech Nitrogen GP’s directors and executive officers beneficially owned and had the right to vote                     Rentech Nitrogen common units at the Rentech Nitrogen special meeting, which represents approximately     % of the Rentech Nitrogen common units entitled to vote at the Rentech Nitrogen special meeting. It is expected that Rentech Nitrogen GP’s directors and executive officers will vote their units “FOR” the merger proposal, although none of them has entered into any agreement requiring them to do so.

Rentech Nitrogen Common Unitholder Proposals. Ownership of Rentech Nitrogen common units does not entitle Rentech Nitrogen common unitholders to make proposals at the Rentech Nitrogen special meeting. Under the Rentech Nitrogen partnership agreement, only its general partner can make a proposal at the Rentech Nitrogen special meeting.

Rentech Nitrogen’s Reasons for the Mergers; Recommendation of Rentech Nitrogen Board

The Rentech Nitrogen Board has determined that the merger agreement and the transactions contemplated by the merger agreement, including the mergers, are advisable, fair and reasonable to and in the best interests of Rentech Nitrogen and its common unitholders, and has unanimously approved and adopted the merger agreement, approved the execution, delivery and performance of the merger agreement and approved the consummation of the transactions contemplated by the merger agreement, including the mergers. The Rentech Nitrogen Board unanimously recommends that the Rentech Nitrogen common unitholders vote “FOR” the proposal to approve and adopt the merger agreement and the transactions contemplated thereby.

In the course of reaching its decision to approve the merger agreement and the transactions contemplated by the merger agreement, the Rentech Nitrogen Board considered a number of factors in its deliberations. For a more complete discussion of these factors, see “Proposal 1: The Mergers—Rentech Nitrogen’s Reasons for the Mergers; Recommendation of Rentech Nitrogen Board.”

Opinion of the Financial Advisor to the Rentech Nitrogen Board

Rentech Nitrogen retained Morgan Stanley & Co. LLC (“Morgan Stanley”) to provide it with financial advisory services and a financial opinion in connection with a possible merger, sale or other strategic business combination. Rentech Nitrogen selected Morgan Stanley to act as its financial advisor based on Morgan Stanley’s qualifications, expertise and reputation and its knowledge of the business and affairs of Rentech Nitrogen. At the meeting of the Rentech Nitrogen Board on August 9, 2015, Morgan Stanley rendered its oral opinion, subsequently confirmed in writing on the same date, to the Rentech Nitrogen Board to the effect that, as of such date, based upon and subject to the assumptions made, procedures followed, matters considered and qualifications and limitations on the scope of the review undertaken by Morgan Stanley as set forth in the written opinion, the merger consideration to be received by the holders of Rentech Nitrogen common units (other than the Rentech Unitholders and CVR Partners and its affiliates) pursuant to the merger agreement was fair from a financial point of view to such holders.

The full text of Morgan Stanley’s written opinion to the Rentech Nitrogen Board, dated as of August 9, 2015, which sets forth, among other things, the assumptions made, procedures followed, matters considered and qualifications and limitations on the scope of the review undertaken by Morgan Stanley in rendering its opinion, is attached to this proxy statement/prospectus as Annex B and is incorporated herein by reference. You are encouraged to read Morgan Stanley’s opinion and the summary of Morgan Stanley’s opinion below carefully and in their entirety. Morgan Stanley’s opinion was rendered for the benefit of the Rentech Nitrogen Board, in its capacity as such, and addressed only the fairness from a financial point of view of the merger consideration pursuant to the merger agreement to the holders of Rentech Nitrogen common units (other than the Rentech Unitholders and CVR Partners and its affiliates) as of the date of the opinion. Morgan Stanley’s opinion did not address any other aspect of the Rentech Nitrogen merger or related transactions, including the prices at which CVR Partners common units will trade following consummation of the mergers or at any time, or any compensation or compensation agreements arising from (or relating to) the mergers that benefit any of Rentech Nitrogen’s officers, directors or employees, or any class of such persons. The opinion was addressed to, and rendered for the benefit of, the Rentech Nitrogen Board and was not intended to, and does not, constitute advice or a recommendation as to how holders of Rentech Nitrogen common units should vote at the Rentech Nitrogen special meeting to be held in connection with the Rentech Nitrogen merger or act on any matter with respect to the Rentech Nitrogen merger or related transactions. The summary of the opinion of Morgan Stanley set forth in this proxy statement/prospectus is qualified in its entirety by reference to the full text of the opinion.

See “Proposal 1: The Mergers—Opinion of the Financial Advisor to the Rentech Nitrogen Board.”

Voting and Support Agreement

Simultaneously with the execution of the merger agreement, CVR Partners entered into the voting and support agreement with the Rentech Unitholders, who collectively hold Rentech Nitrogen common units representing approximately 59.7% of the outstanding Rentech Nitrogen common units as of the date of this proxy statement/prospectus, which is a sufficient number of Rentech Nitrogen common units to approve the merger proposal without the affirmative vote of any other Rentech Nitrogen common unitholders.

In accordance with the voting and support agreement, subject to certain exceptions, the Rentech Unitholders have agreed, among other things, to vote or cause to be voted all of their respective Rentech Nitrogen common units in favor of the merger proposal and against alternative proposals or other proposals made in opposition to the merger proposal and other actions or transactions which might materially impede or interfere with the mergers or the transactions contemplated by the merger agreement. The Rentech Unitholders also agreed to provide CVR Partners with an irrevocable proxy over all of their respective Rentech Nitrogen common units, which will empower CVR Partners, subject to the terms of the voting and support agreement, to vote those units in favor of the mergers and the transactions contemplated thereby on behalf of the Rentech Unitholders. The foregoing obligations and proxy will terminate upon the earliest to occur of (a) the consummation of the mergers and (b) the termination of the merger agreement in accordance with its terms. Upon either a partnership change in recommendation made in accordance with the merger agreement or the issuance of an injunction by a governmental authority prohibiting the consummation of the transactions in accordance with the merger agreement or the voting and irrevocable proxy covenants described above, such covenants will have no further effect. The other covenants described above shall continue in full force and effect until the voting and support agreement is validly terminated.

The Rentech Unitholders have also agreed to certain restrictions under the voting and support agreement, including but not limited to: (i) a restriction on transferring their respective Rentech Nitrogen common units and (ii) a restriction on soliciting or encouraging alternative proposals. Furthermore, each of the Rentech Unitholders agreed to promptly notify CVR Partners of any alternative proposal that they receive and to keep CVR Partners reasonably informed regarding the material developments of any such alternative proposals. CVR Partners and the Rentech Unitholders have also agreed to a mutual two-year non-solicitation of employees commencing at the effective time.

For a more complete discussion of the voting and support agreement, see “Proposal 1: The Mergers—Voting and Support Agreement.”

Separation Agreement

It is a condition to the obligation of CVR Partners to complete the mergers that Rentech Nitrogen sell or spin off the Pasadena Facility and its related business, in each case subject to certain terms specified in the merger agreement and, if applicable, the separation agreement. The separation agreement is not expected to be executed unless the sale of the Pasadena Facility and its related businesses has not been completed by the closing date for the mergers, and certain other conditions have been met. The separation agreement, if ultimately entered into, would govern the terms of the separation of Rentech Nitrogen’s Pasadena business from its other assets and the distribution to the Rentech Nitrogen common unitholders of equity interests in a new entity holding the Pasadena business (“SpinCo”). Subject to the receipt of required governmental and other consents and approvals, in order to accomplish the separation, the separation agreement will provide for Rentech Nitrogen and SpinCo to transfer specified assets and liabilities between the two companies to separate the Pasadena business from Rentech Nitrogen’s remaining businesses. Rentech Nitrogen will retain all other assets and liabilities. For a more complete discussion of the separation agreement, see “Proposal 1: The Mergers—Separation Agreement.”

Registration Rights Agreement

Simultaneously with the execution of the merger agreement, CVR Partners and Coffeyville Resources, LLC (“Coffeyville”) entered into a registration rights agreement (the “registration rights agreement”) with Rentech Nitrogen Holdings, Inc. and DSHC, LLC (the “Rentech Subsidiary Holders”). Pursuant to the registration rights agreement, among other things, (i) no later than the 30th day following the closing date of the mergers, CVR Partners will file a shelf registration statement with the SEC to permit the public resale of the CVR Partners common units received by the Rentech Subsidiary Holders as consideration in the mergers, (ii) the Rentech

Subsidiary Holders will have certain rights to participate in certain future underwritten public offerings of CVR Partners common units and (iii) CVR Partners will be obligated to facilitate an underwritten offering of the CVR Partners common units received by the Rentech Subsidiary Holders as consideration in the mergers, subject to certain conditions. The Rentech Subsidiary Holders may assign certain of their registration rights under the registration rights agreement in certain circumstances. For a more complete discussion of the registration rights agreement, see “Proposal 1: The Mergers—Registration Rights Agreement.”

Rentech Unitholders Transaction Agreement

Simultaneously with the execution of the merger agreement, CVR Partners and Coffeyville entered into a transaction agreement (the “Rentech Unitholders transaction agreement”) with the Rentech Unitholders pursuant to which the Rentech Unitholders will have the right to appoint two directors to the board of directors of CVR Partners GP (the “CVR Partners Board”), subject to certain minimum ownership thresholds. The Rentech Unitholders transaction agreement also contains certain lock-up and standstill provisions to which the Rentech Unitholders are subject. For a more complete discussion of the transaction agreement, see “Proposal 1: The Mergers—Rentech Unitholders Transaction Agreement.”

GSO Transaction Agreement

In connection with the closing of the mergers, GSO Capital Partners LP (“GSO”) and certain of its affiliated or managed funds (collectively, the “GSO Funds”), among other things, will receive a substantial portion of the CVR Partners common units. For more information, see “—Interests of Rentech in the Mergers.” Simultaneously with the execution of the merger agreement, CVR Partners also entered into a transaction agreement (the “GSO transaction agreement”) with GSO and the GSO Funds, pursuant to which the GSO Funds are subject to certain lock-up and standstill provisions with respect to the CVR Partners common units they receive in connection with the mergers. For a more complete discussion of the GSO transaction agreement, see “Proposal 1: The Mergers—GSO Transaction Agreement.”

Commitment Letter

Simultaneously with the execution of the merger agreement, CVR Partners entered into a commitment letter (the “commitment letter”) with Coffeyville, pursuant to which Coffeyville has committed to, on the terms and subject to the conditions set forth in the commitment letter, make available to CVR Partners term loan financing of up to $150 million, which amounts would be available to fund the repayment of all of the loans outstanding under Rentech Nitrogen’s existing $50 million credit facility with General Electric Capital Corporation (the “GE Credit Facility”), the cash consideration and transaction related expenses. Such term loan, if drawn, would have a one year term. For a more complete discussion of the commitment letter, see “Proposal 1: The Mergers—Commitment Letter.”

CVR Partners Common Unitholder Approval is Not Required

CVR Partners common unitholders are not required to adopt the merger agreement or approve the mergers or the issuance of CVR Partners common units in connection with the mergers.

Ownership of CVR Partners After the Mergers

CVR Partners is expected to issue approximately 40.7 million CVR Partners common units to former Rentech Nitrogen common unitholders pursuant to the mergers. Further, the number of CVR Partners common units outstanding will increase after the date of this proxy statement/prospectus if CVR Partners sells additional common units to the public. Based on the number of CVR Partners common units outstanding as of the date of

this proxy statement/prospectus, immediately following the completion of the mergers, CVR Partners expects to have approximately 113.8 million common units outstanding. Based on the 30-day volume-weighted average price of CVR Partners common units as of August 7, 2015, the Rentech Unitholders and the GSO Funds are expected to hold approximately 8.7% and 12.5%, respectively, of the aggregate number of CVR Partners common units outstanding immediately after the mergers. For more information regarding the exchange agreement between Rentech and the GSO Funds in connection with the mergers, see “—Interests of Rentech in the Mergers.” The Rentech Nitrogen common unitholders other than the Rentech Unitholders and the GSO Funds are therefore expected to hold approximately 14.5% of the aggregate number of CVR Partners common units outstanding immediately after the mergers. Holders of CVR Partners common units are not entitled to elect CVR Partners’ general partner and have only limited voting rights on matters affecting CVR Partners’ business.

Interests of Directors and Executive Officers of Rentech Nitrogen GP in the Mergers

Rentech Nitrogen GP’s directors and executive officers have certain financial interests in the mergers that are different from, or in addition to, the interests of Rentech Nitrogen common unitholders generally. The members of the Rentech Nitrogen Board were aware of and considered these interests, among other matters, in evaluating and negotiating the merger agreement and the mergers, and in recommending to Rentech Nitrogen’s unitholders that the merger agreement be approved.

These interests include:

Interests of Rentech in the Mergers

Rentech has certain financial interests in the mergers that are different from, or in addition to, the interests of Rentech Nitrogen common unitholders generally. In connection with the execution of the merger agreement, Rentech and certain of its subsidiaries entered into a Waiver and Amendment of Certain Loan and Equity Documents (the “Waiver”). The Waiver covers (i) that certain Amended and Restated Term Loan Credit Agreement, dated as of February 12, 2015 (as amended or modified to date, the “A&R GSO Credit Agreement”), by and among certain Rentech subsidiaries, the GSO Funds, and Credit Suisse AG, Cayman Islands Branch (the “Agent”), (ii) that certain Amended and Restated Guaranty Agreement, dated as of February 12, 2015 (as

amended or modified to date, the “Guaranty”), by and among Rentech and certain subsidiaries of Rentech party thereto in favor of the Agent and (iii) that certain Subscription Agreement, dated as of April 9, 2014 (as amended or modified to date, the “Subscription Agreement”) by and among Rentech, the GSO Funds and GSO.

Pursuant to the Waiver, the lenders under the A&R GSO Credit Agreement, the Agent and GSO, as applicable, agreed to waive compliance with the A&R GSO Credit Agreement, Guaranty and certain restrictions in the Subscription Agreement, solely to the extent they restrict or prohibit Rentech, Rentech Nitrogen and Rentech Nitrogen GP’s ability to enter into the merger agreement, the voting and support agreement or the transactions contemplated thereby. The Waiver also provides that, in lieu of the repurchase of the preferred stock and repayment of the loans as provided in the Subscription Agreement and A&R GSO Credit Agreement, the GSO Funds will receive certain other consideration, including CVR Partners common units, described under “Proposal 1: The Mergers—Interests of Rentech in the Mergers.” The Waiver also attaches drafts of an amended and restated credit agreement (“A&R Credit Agreement”), amended and restated guaranty (“A&R Guaranty”) and a preferred equity exchange and discharge agreement (the “exchange agreement”) relating to the Series E Convertible Preferred Stock of Rentech, each of which would be entered into at the closing under the merger agreement. For more information, see “Proposal 1: The Mergers—Interests of Rentech in the Mergers.”

Risks Relating to the Mergers and Ownership of CVR Partners Common Units

Rentech Nitrogen common unitholders should consider carefully all the risk factors together with all of the other information contained in or incorporated by reference in this proxy statement/prospectus before deciding how to vote. Risks relating to the mergers and ownership of CVR Partners common units are described in the section titled “Risk Factors.” These risks include, but are not limited to, those described below:

Material U.S. Federal Income Tax Consequences of the Mergers

Tax matters associated with the mergers are complicated. The U.S. federal income tax consequences of the mergers to a Rentech Nitrogen common unitholder will depend, in part, on such unitholder’s own tax situation. The tax discussions contained herein focus on the U.S. federal income tax consequences generally applicable to individuals who are residents or citizens of the United States that hold their Rentech Nitrogen common units as capital assets, and these discussions have only limited application to other unitholders, including those subject to special tax treatment. Rentech Nitrogen common unitholders are urged to consult their tax advisors for a full understanding of the U.S. federal, state, local and foreign tax consequences of the mergers that will be applicable to them.

In connection with the mergers, Rentech Nitrogen expects to receive an opinion from Latham & Watkins LLP to the effect that (i) except to the extent that the Section 707 Consideration (as defined below) causes the transaction to be treated as a “disguised sale,” holders of Rentech Nitrogen common units (other than Rentech and its affiliates and any holder of the CVR Partners affiliate units) will not recognize any income or gain as a result of the Rentech Nitrogen merger (other than any (a) income or gain resulting from the actual or constructive distribution of cash, including as a result of any decrease in partnership liabilities pursuant to Section 752 of the Code, or (b) any liabilities incurred other than in the ordinary course of business of Rentech Nitrogen or any of its subsidiaries); provided that such opinion will not extend to any Rentech Nitrogen common unitholder who acquired common units from Rentech Nitrogen in exchange for property other than cash; and (ii) at least 90% of the gross income of Rentech Nitrogen for all of the calendar year prior to the year in which the mergers occur and all calendar quarters of the year in which the mergers occur ending before the closing date of the mergers for which the necessary financial information is available is from sources treated as “qualifying income” within the meaning of Section 7704(d) of the Code.

In connection with the mergers, CVR Partners expects to receive an opinion from Vinson & Elkins L.L.P. to the effect that (i) CVR Partners will not recognize any income or gain as a result of the mergers (other than any gain resulting from any decrease in partnership liabilities pursuant to Section 752 of the Code); (ii) no gain or loss will be recognized by holders of CVR Partners common units as a result of the mergers (other than any gain resulting from any decrease in partnership liabilities pursuant to Section 752 of the Code); and (iii) at least 90% of the combined gross income of CVR Partners and Rentech Nitrogen for all of the calendar year prior to the year in which the mergers occur and all calendar quarters of the calendar year in which the mergers occur ending before the closing date for which the necessary financial information is available is from sources treated as “qualifying income” within the meaning of Section 7704(d) of the Code.

Opinions of counsel, however, are subject to certain limitations and are not binding on the Internal Revenue Service (“IRS”) and no assurance can be given that the IRS would not successfully assert a contrary position regarding the mergers and the opinions of counsel. In addition, such opinions will be based upon certain factual assumptions and representations, warranties and covenants made by the officers of CVR Partners, CVR Partners GP, Rentech Nitrogen and Rentech Nitrogen GP and any of their respective affiliates. See “Material U.S. Federal Income Tax Consequences of the Mergers” for a more complete discussion of the U.S. federal income tax consequences of the mergers.

Accounting Treatment of the Mergers

In accordance with accounting principles generally accepted in the United States and in accordance with the Financial Accounting Standards Board’s Accounting Standards Codification Topic 805—Business Combinations, CVR Partners will account for the mergers as an acquisition of a business.

Listing of CVR Partners Common Units; Delisting and Deregistration of Rentech Nitrogen Common Units

CVR Partners common units are currently listed on the NYSE under the symbol “UAN.” It is a condition to closing that the CVR Partners common units to be issued in the mergers to Rentech Nitrogen common unitholders be approved for listing on the NYSE, subject to official notice of issuance.

Rentech Nitrogen common units are currently listed on the NYSE under the ticker symbol “RNF.” If the mergers are completed, Rentech Nitrogen common units will cease to be listed on the NYSE and will be deregistered under the Exchange Act.

No Appraisal Rights

Appraisal rights are not available in connection with the mergers under the Delaware LP Act or under the Rentech Nitrogen partnership agreement. See “Proposal 1: The Mergers—No Appraisal Rights.”

Conditions to Consummation of the Mergers

CVR Partners and Rentech Nitrogen currently expect to complete the mergers in the fourth quarter of 2015, subject to receipt of required Rentech Nitrogen common unitholder and regulatory approvals and clearances, the sale or spin-off by Rentech Nitrogen of the Pasadena Facility and its related business, in each case subject to certain terms specified in the merger agreement and, if applicable, the separation agreement, and to the satisfaction or waiver of the other conditions to the transactions contemplated by the merger agreement described below.

As more fully described in this proxy statement/prospectus, each party’s obligation to complete the transactions contemplated by the merger agreement depends on a number of customary closing conditions being satisfied or, where legally permissible, waived, including the following:

The obligations of CVR Partners to effect the mergers are subject to the satisfaction or waiver of the following additional conditions:

The obligation of Rentech Nitrogen to effect the mergers is subject to the satisfaction or waiver of the following additional conditions:

Regulatory Approvals and Clearances Required for the Mergers

Consummation of the mergers is subject to the expiration or termination of any applicable waiting period under the HSR Act. On August 21, 2015, CVR Partners and Rentech Nitrogen filed Notification and Report Forms with the Antitrust Division of the Department of Justice, which is referred to as the Antitrust Division, and the Federal Trade Commission, which is referred to as the FTC. See “Proposal 1: The Mergers—Regulatory Approvals and Clearances Required for the Mergers.”

No Solicitation by Rentech Nitrogen of Alternative Proposals

Under the merger agreement, Rentech Nitrogen and Rentech Nitrogen GP have agreed that they will not, and will cause their subsidiaries and their respective directors, officers and employees not to, and will use commercially reasonable efforts to cause their respective other representatives not to, directly or indirectly:

Rentech Nitrogen and Rentech Nitrogen GP agreed that any such discussions or negotiations in progress as of the date of the merger agreement had been terminated prior to the execution and delivery of the merger agreement. In addition, Rentech Nitrogen and Rentech Nitrogen GP agreed that, promptly following the date of the merger agreement, they will (i) terminate access that was granted to any person to any “data room” (virtual or physical) that was established in connection with the transactions contemplated by the merger agreement, and (ii) exercise any contractual rights available to any of them to cause each person who received non-public or confidential information of any of Rentech Nitrogen or Rentech Nitrogen GP or any of their subsidiaries to cause such persons to promptly return to Rentech Nitrogen or Rentech Nitrogen GP or destroy such information.

Notwithstanding these restrictions, the merger agreement provides that, under specified circumstances at any time prior to Rentech Nitrogen common unitholders voting in favor of the merger proposal, Rentech Nitrogen may furnish information, including confidential information, with respect to it and its subsidiaries to, and participate in discussions or negotiations with, any third party that makes a written alternative proposal (which was not solicited after the execution of the merger agreement and that did not result from a violation of the no solicitation restrictions described above) that the Rentech Nitrogen Board believes is bona fide, and (after consultation with its financial advisors and outside legal counsel) that the Rentech Nitrogen Board determines in good faith constitutes or could reasonably be expected to lead to or result in a superior proposal, provided that Rentech Nitrogen complies with certain provisions of the merger agreement as described under “The Merger Agreement—No Solicitation by Rentech Nitrogen of Alternative Proposals.”

Rentech Nitrogen has also agreed in the merger agreement that it will promptly, and in any event within twenty-four hours after receipt, advise CVR Partners in writing if any proposal, offer or inquiry is received by, any information is requested from, or any discussions or negotiations are sought to be initiated with, Rentech

Nitrogen or Rentech Nitrogen GP in respect of any alternative proposal and will, in any such notice to CVR Partners, indicate the identity of the person making such proposal, offer, or inquiry and the terms and conditions of any proposals or offers (and will include with such notice copies of any written materials received from or on behalf of such person relating to the proposal, offer, inquiry or request). In addition, Rentech Nitrogen will promptly keep CVR Partners reasonably informed of all material developments affecting the status and terms of any such proposals, offers, inquiries or requests and promptly, and in any event within twenty-four hours, provide CVR Partners with copies of any additional written materials received by Rentech Nitrogen or Rentech Nitrogen GP or that Rentech Nitrogen or Rentech Nitrogen GP have delivered to any third party who made an alternative proposal that relate to such proposals, offers, inquiries or requests) and of the status of any such discussions or negotiations.

Rentech Nitrogen has also agreed in the merger agreement that neither it, Rentech Nitrogen GP nor any of the subsidiaries of Rentech Nitrogen will enter into any agreement with any person subsequent to the date of the merger agreement that prohibits Rentech Nitrogen from providing any information to CVR Partners in accordance with the “no solicitation” provisions in the merger agreement (including those described above).

All of the standstill provisions, if any, included in each effective confidentiality agreement that Rentech Nitrogen or Rentech Nitrogen GP entered into prior to the date of the merger agreement automatically terminated upon entry into the merger agreement, by the terms of such confidentiality agreements.

Change in Rentech Nitrogen Board Recommendation

The merger agreement provides that, except as otherwise expressly provided for in the merger agreement, the Rentech Nitrogen Board will not (i) withdraw, modify or qualify (or publicly propose to withdraw, modify or qualify), in any manner adverse to CVR Partners, the recommendation of the Rentech Nitrogen Board that Rentech Nitrogen’s unitholders adopt the merger agreement, (ii) fail to include such recommendation in this proxy statement/prospectus, or (iii) publicly approve or recommend or publicly propose to approve or recommend, any alternative proposal. Rentech Nitrogen’s taking or failing to take, as applicable, any of the actions described above is referred to as a “partnership change in recommendation.”

The merger agreement also provides that the Rentech Nitrogen Board will not: (i) approve, adopt or recommend, or publicly propose to approve, adopt or recommend, or allow Rentech Nitrogen or any of its subsidiaries to execute or enter into, any letter of intent, memorandum of understanding, agreement in principle, merger agreement, acquisition agreement, option agreement, joint venture agreement, partnership agreement, or other similar contract or any tender or exchange offer providing for, with respect to, or in connection with any alternative proposal; or (ii) resolve, agree or publicly propose to, or permit Rentech Nitrogen or any of its representatives to agree or publicly propose to, take any of the actions referred to in this paragraph or the immediately preceding paragraph.

Subject to the satisfaction of specified conditions in the merger agreement described under “The Merger Agreement—Change in Rentech Nitrogen Board Recommendation,” notwithstanding the terms described above, if prior to obtaining the Rentech Nitrogen unitholder approval, Rentech Nitrogen receives a written alternative proposal (and such proposal is not withdrawn) that the Rentech Nitrogen Board believes is bona fide and which did not result from any breach of the no solicitation provisions in the merger agreement summarized above, and the Rentech Nitrogen Board, after consultation with its financial advisors and outside legal counsel, concludes that such alternative proposal constitutes a superior proposal, and that the failure to effect a partnership change in recommendation would result in a breach of its duties under applicable law, then the Rentech Nitrogen Board may at any time prior to obtaining the Rentech Nitrogen unitholder approval, effect a partnership change in recommendation.

Termination of the Merger Agreement

CVR Partners and Rentech Nitrogen may terminate the merger agreement at any time prior to the closing of the mergers by mutual written consent.

In addition, either CVR Partners or Rentech Nitrogen may terminate the merger agreement at any time prior to the effective time by written notice to the other party in the event that:

CVR Partners may terminate the merger agreement in the event that:

Rentech Nitrogen may terminate the merger agreement in the event that:

Expenses and Termination Fee

Generally, all fees and expenses incurred in connection with the transactions contemplated by the merger agreement will be the obligation of the respective party incurring such fees and expenses, except that CVR Partners will pay the expenses incurred in connection with the filings required to be made under the HSR Act and CVR Partners and Rentech Nitrogen will each pay one-half of the expenses incurred in connection with the filing, printing and mailing of this proxy statement/prospectus.

The merger agreement provides that Rentech Nitrogen will pay to CVR Partners or CVR Partners will pay to Rentech Nitrogen an amount equal to $10,000,000, as a reimbursement of expenses, upon the occurrence of certain events. Rentech Nitrogen may furthermore be required to pay to CVR Partners a termination fee of $31,200,000 under certain circumstances.

Comparison of Rights of CVR Partners Common Unitholders and Rentech Nitrogen Common Unitholders

Rentech Nitrogen common unitholders will own CVR Partners common units following the completion of the mergers, and their rights associated with those CVR Partners common units will be governed by the CVR Partners partnership agreement, which differs in a number of respects from the Rentech Nitrogen partnership agreement, and the Delaware LP Act.

Litigation Relating to the Mergers

In connection with the mergers, purported unitholders of Rentech Nitrogen have filed a class action lawsuit against Rentech Nitrogen, Rentech Nitrogen GP, Rentech Nitrogen Holdings, Inc. (“Rentech Holdings”), Rentech, CVR Partners, DSHC, LLC (“DSHC”), Merger Sub 1, Merger Sub 2, and the members of the Rentech Nitrogen Board. Among other remedies, the plaintiffs in these actions seek to enjoin the mergers. The outcome of any such litigation is uncertain.

This lawsuit is at a preliminary state. CVR Partners and Rentech Nitrogen believe that this lawsuit is without merit and intend to defend against it vigorously.

SELECTED HISTORICAL CONSOLIDATED FINANCIAL DATA OF CVR PARTNERS

The following selected historical consolidated financial data as of and for the six months ended June 30, 2015 and June 30, 2014 are derived from CVR Partners’ unaudited condensed consolidated interim financial statements and the selected historical consolidated financial data as of and for each of the years ended December 31, 2014, 2013, 2012, 2011, and 2010 are derived from CVR Partners’ audited consolidated financial statements. You should read the following data in conjunction with “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and the consolidated financial statements and the related notes thereto set forth in CVR Partners’ Annual Report on Form 10-K for the year ended December 31, 2014 and its Quarterly Report on Form 10-Q for the quarter ended June 30, 2015, which are incorporated by reference into this proxy statement/prospectus. See “Where You Can Find More Information.” You should not assume the results of operations for any past period indicate results for any future period.

SELECTED HISTORICAL CONSOLIDATED FINANCIAL DATA OF RENTECH NITROGEN

The following tables include Rentech Nitrogen’s selected summary financial data for the six months ended June 30, 2015 and 2014 and the years ended December 31, 2014, 2013, 2012 and 2011, the three months ended December 31, 2011 and 2010 and the two fiscal years ended September 30, 2011 and 2010 which are derived from the unaudited or audited financial statements of Rentech Nitrogen for the corresponding periods. During 2012, the Rentech Nitrogen Board approved a change in Rentech Nitrogen’s fiscal year end from September 30 to December 31. The statement of operations data for the calendar year ended December 31, 2011 was derived by deducting the statement of operations data for the three months ended December 31, 2010 from the statement of operations data for the fiscal year ended September 30, 2011 and then adding the statement of operations data from the three months ended December 31, 2011.

In the fiscal years ended September 30, 2011 and 2010, Rentech Energy Midwest Corporation (“REMC”), Rentech Nitrogen’s predecessor, was a wholly-owned subsidiary of Rentech. At the closing of Rentech Nitrogen’s initial public offering on November 9, 2011, Rentech Nitrogen acquired all of the member interests of REMC. For periods prior to such closing, the summary financial data presented below reflects REMC on a stand-alone or “carve-out” basis from Rentech, and certain corporate overhead costs were allocated to REMC and certain transactions between REMC and Rentech were re-categorized as if REMC were a standalone entity. Prior to the closing, REMC was not a publicly traded company and did not report its financial data in accordance with public company financial disclosure requirements. As a result, the summary financial data of REMC may not be comparable to the summary financial data of Rentech Nitrogen.

The operations of the Pasadena Facility are included below effective November 1, 2012, the date of the closing of the acquisition of Agrifos LLC (now known as Rentech Nitrogen Pasadena Holdings, LLC).

The data below should be read in conjunction with Rentech Nitrogen’s Annual Report on Form 10-K for the year ended December 31, 2014 and its Quarterly Report on Form 10-Q for the quarter ended June 30, 2015, as well as Rentech Nitrogen’s historical financial statements and notes thereto, which are incorporated by reference into this proxy statement/prospectus. See “Where You Can Find More Information.”

SELECTED UNAUDITED PRO FORMA COMBINED FINANCIAL INFORMATION

The following selected unaudited pro forma combined balance sheet as of June 30, 2015 reflects the mergers as if they had occurred on June 30, 2015. The following selected unaudited pro forma combined statements of operations for the six months ended June 30, 2015 and the year ended December 31, 2014 reflect the mergers as if they had occurred on January 1, 2014.

The following selected unaudited pro forma combined financial information has been prepared for illustrative purposes only and is not necessarily indicative of what the combined partnership’s financial position or results of operations actually would have been had the mergers been completed as of the dates indicated. In addition, the following selected unaudited pro forma combined financial information does not purport to project the future financial position or operating results of the combined partnership. Future results may vary significantly from the results reflected because of various factors. The following selected unaudited pro forma combined financial information has been developed from and should be read in conjunction with the financial statements and related notes contained in CVR Partners’ and Rentech Nitrogen’s Annual Reports on Form 10-K for the year ended December 31, 2014 and subsequent Quarterly Reports on Form 10-Q, all of which are incorporated by reference into this proxy statement/prospectus, as well as the unaudited pro forma condensed combined financial statements and accompanying notes contained in this proxy statement/prospectus. See the section titled “Unaudited Pro Forma Condensed Combined Financial Information.”

Selected Unaudited Pro Forma Combined Balance Sheet Data as of June 30, 2015

Selected Unaudited Pro Forma Combined Statement of Operations Data for the Six Months Ended June 30, 2015

Selected Unaudited Pro Forma Combined Statement of Operations Data for the Year Ended December 31, 2014

UNAUDITED COMPARATIVE PER UNIT INFORMATION

The following table sets forth (i) historical per unit information of CVR Partners, (ii) the unaudited pro forma per unit information of CVR Partners after giving pro forma effect to the mergers and the transactions contemplated thereby, including CVR Partners’ issuance of 1.04 CVR Partners common units for each outstanding Rentech Nitrogen common unit (other than certain common units held by Rentech Nitrogen or CVR Partners or their wholly owned subsidiaries (except for the CVR Partners affiliate units), which will be cancelled) and (iii) the historical and equivalent pro forma per unit information for Rentech Nitrogen.

You should read this information in conjunction with (i) the summary historical consolidated financial data included elsewhere in this proxy statement/prospectus, (ii) the historical consolidated financial statements of both Rentech Nitrogen and CVR Partners and related notes that are incorporated by reference in this proxy statement/prospectus and (iii) the “Unaudited Pro Forma Condensed Combined Financial Information” and related notes included elsewhere in this proxy statement/prospectus. The unaudited pro forma per unit information does not necessarily represent what the actual results of operations of Rentech Nitrogen and CVR Partners would have been had the proposed mergers been completed in another period or to project Rentech Nitrogen’s and CVR Partners’ results of operations that may be achieved if the proposed mergers are completed.