| Disaggregation of revenue |
The following table presents the Partnership’s revenue, disaggregated by major product: | | | | | | | | | | | | | | | | | | | | | | | | | Three Months Ended June 30, | | | | Six Months Ended June 30, | | | | (in thousands) | 2020 | | 2019 | | 2020 | | 2019 | | Ammonia | $ | 36,765 | | | $ | 49,954 | | | $ | 50,911 | | | $ | 63,306 | | | UAN | 55,294 | | | 73,542 | | | 102,308 | | | 137,606 | | | Urea products | 3,535 | | | 5,006 | | | 7,068 | | | 9,677 | | | Net sales, exclusive of freight and other | 95,594 | | | 128,502 | | | 160,287 | | | 210,589 | | | Freight revenue | 6,954 | | | 7,139 | | | 14,677 | | | 15,157 | | | Other revenue | 2,543 | | | 2,019 | | | 5,208 | | | 3,787 | | | Net sales | $ | 105,091 | | | $ | 137,660 | | | $ | 180,172 | | | $ | 229,533 | |
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| Summary of deferred revenue activity |
A summary of the deferred revenue activity for the six months ended June 30, 2020 is presented below: | | | | | | | | | (in thousands) | | | | | Balance at December 31, 2019 | $ | 27,841 | | | | | Add: | | | | | New prepay contracts entered into during the period (1) | 18,025 | | | | | Less: | | | | | Revenue recognized that was included in the contract liability balance at the beginning of the period | 26,949 | | | | | Revenue recognized related to contracts entered into during the period | 15,943 | | | | | Other changes | 308 | | | | | Balance at June 30, 2020 | $ | 2,666 | | | |
(1) Includes $16.6 million where payment associated with prepaid contracts was collected as of June 30, 2020.
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