As discussed in Note 1, we primarily derive our revenues from the sales of various chemical products. The following table presents our net sales disaggregated by our principal markets, which disaggregation is consistent with other financial information utilized or provided outside of our consolidated financial statements:

	Three Months Ended
	March 31,
	2020		2019
	(Dollars In Thousands)
Net sales:
Agricultural products	$	41,458	$	46,820
Industrial acids and other chemical products		35,206		37,850
Mining products		6,747		9,482
Total net sales	$	83,411	$	94,152

Although most of our contracts have an original expected duration of one year or less, for our contracts with a duration greater than one year, the average remaining expected duration was approximately 15 months at March 31, 2020.

Liabilities associated with contracts with customers (contract liabilities) primarily relate to deferred revenue and customer deposits associated with cash payments received in advance from customers for volume shortfall charges and product shipments. We had approximately $4.2 million and $3.6 million of contract liabilities as of March 31, 2020 and December 31, 2019, respectively. For the three months ended March 31, 2020 and 2019, revenues of $0.5 million and $1.4 million, respectively, were recognized and included in the balance at the beginning of the respective period.