Net sales for our market pulp segment decreased 9.0% to $150.1 million in 2011 from $164.9 million in 2010, reflecting a 6.0% decrease in the average sales price per ton combined with a 3.2% decrease in sales volume compared to 2010.
Net sales for our other segment increased 22.5% to $153.6 million in 2011 from $125.4 million in 2010. The improvement in 2011 is due to a 14.9% increase in the average sales price per ton combined with a 6.6% increase in sales volume compared to 2010.
Cost of sales. Cost of sales, including depreciation, amortization, and depletion, was $1,585.6 million in 2011 compared to $1,538.2 million in 2010. Our gross margin, excluding depreciation, amortization, and depletion, was 15.2% for 2011 compared to 12.1% for 2010, reflecting higher average sales prices during 2011. Depreciation, amortization, and depletion expenses were $125.3 million for 2011, compared to $127.4 million for 2010.
Selling, general, and administrative. Selling, general, and administrative expenses increased to $78.0 million in 2011 from $71.0 million in 2010, primarily due to inflation of personnel related costs and certain non-recurring costs including professional fees and severance.Interest expense. Interest expense was $126.6 million in 2011, compared to $128.1 million in 2010. Goodwill impairment. Results for 2011 included a goodwill impairment charge of $18.7 million, which represents a write-off of the full balance of goodwill. Restructuring and other charges. Restructuring and other charges of $24.5 million in 2011 reflect the permanent shut down of the No. 2 coated groundwood paper machine at our mill in Bucksport, Maine, and two supercalendered paper machines at our mill in Sartell, Minnesota. These charges include $15.0 million of severance and benefit costs, $7.1 million of accelerated depreciation, and $2.3 million due to write-off of spare parts and inventory. Other loss (income), net. In 2011 other losses, net included $26.1 million in pre-tax net losses related to the early retirement of debt in connection with our debt refinancing. The results for 2010 included other income, net of $0.9 million. Reconciliation of Net Income to Adjusted EBITDA The agreements governing our debt contain financial and other restrictive covenants that limit our ability to take certain actions, such as incurring additional debt or making acquisitions. Although we do not expect to violate any of the provisions in the agreements governing our outstanding indebtedness, these covenants can result in limiting our long-term growth prospects by hindering our ability to incur future indebtedness or grow through acquisitions.