COMMITMENTS

We lease certain plants, warehouses, terminals, office facilities, railcars and various types of equipment under operating leases, some of which include rent payment escalation clauses, with lease terms ranging from one to ten years. In addition to minimum lease payments, some of our office facility leases require payment of our proportionate share of real estate taxes and building operating expenses.

In 2013, we entered into an ammonia supply agreement with CF (the “CF Ammonia Supply Agreement”) that commenced in 2017, under which Mosaic agreed to purchase approximately 545,000 to 725,000 tonnes of ammonia per year during a term that may extend until December 31, 2032 at a price tied to the prevailing price of U.S. natural gas.

We have long-term agreements for the purchase of sulfur, which is used in the production of phosphoric acid, and natural gas, which is a significant raw material, used primarily in the solution mining process in our Potash segment and used in our phosphate concentrates plants. Also, we have agreements for capital expenditures primarily in our Potash segments related to our expansion projects.

A schedule of future minimum long-term purchase commitments, based on expected market prices as of December 31, 2018, and minimum lease payments under non-cancelable operating leases as of December 31, 2018 is as follows:



(in millions)	Purchase Commitments		Operating Leases
2019	$	2,586.5	$	97.5
2020	588.9		76.8
2021	495.7		54.7
2022	375.5		36.6
2023	261.1		28.1
Subsequent years	1,437.9		30.9
	$	5,745.6	$	324.6

Rental expense for 2018, 2017 and 2016 was $270.3 million, $114.0 million and $111.0 million, respectively. Purchases made under long-term commitments in 2018, 2017 and 2016 were $2.0 billion, $1.9 billion and $1.6 billion, respectively.

Most of our export sales of potash crop nutrients are marketed through a North American export association, Canpotex, which may fund its operations in part through third-party financing facilities. As a member, Mosaic or our subsidiaries are contractually obligated to reimburse Canpotex for their pro rata share of any operating expenses or other liabilities incurred. The reimbursements are made through reductions to members’ cash receipts from Canpotex.

We incur liabilities for reclamation activities and Gypstack closures in our Florida and Louisiana operations where, in order to obtain necessary permits, we must either pass a test of financial strength or provide credit support, typically in the form of cash deposits, surety bonds or letters of credit. The surety bonds generally expire within one year or less but a substantial portion of these instruments provide financial assurance for continuing obligations and, therefore, in most cases, must be renewed on an annual basis. As of December 31, 2018, we had $497.7 million in surety bonds outstanding, of which $203.3 million is for reclamation obligations, primarily related to mining in Florida. In addition, included in this amount is $233.7 million, reflecting our updated closure cost estimates, delivered to EPA as a substitute for the financial assurance provided through the Plant City Trust. The remaining balance in surety bonds outstanding of $60.7 million is for other matters.