costs for ingredients and packaging materials adversely affected results for second quarter and first half 2022, higher volumes did provide some benefit as certain plant manufacturing overhead costs are generally fixed and do not change significantly when volume increases.
Our supply chain has continued to be extremely challenging in 2022, as our supplier lead times have expanded greatly, or our suppliers have been unable to meet promised delivery dates, some of which is due to rail and truck delivery limitations and constraints. In some cases, we are unable to secure timely delivery of additional ingredients and packaging materials to meet our higher demand in 2022, and therefore, are limiting our customer sales order volumes of some products. Company Management is continuing to focus on the supply chain and possible delays and disruptions, but this area continues to have much less predictability compared to past history. Although we are cautiously optimistic, it is possible that supply chain disruptions could result in the temporary shut-down of one or more manufacturing lines resulting in lost sales and profits in 2022. The Company has been able to meet substantially all of its labor needs to date for our seasonal increases in production and we believe that we will meet this challenge in 2022, but again, the current tight labor market has created more uncertainty than in the past.
Certain cost and expense reductions, which include Company initiatives to reduce costs, mitigated some of the cost increase in adjusted product cost of goods sold in second quarter and first half 2022 compared to the corresponding period in the prior year. The Company is focused on the longer term and therefore is continuing to make investments in plant manufacturing operations to meet new consumer and customer product demands, achieve product quality improvements, and increase operational efficiencies in order to provide genuine value to consumers.
Selling, marketing and administrative expenses were $20,674 in second quarter 2022 compared to $32,378 in second quarter 2021, and first half 2022 selling, marketing and administrative expenses were $47,747 compared to $59,187 in first half 2021. Selling, marketing and administrative expenses include $(11,693) and $5,208 of certain deferred compensation expenses (credits) in second quarter 2022 and 2021, respectively, and $(17,029) and $8,244 of certain deferred compensation expenses in first half 2022 and 2021, respectively. As discussed above, these expenses (credits) principally result from changes in the market value of investments and investment income from trading securities relating to compensation deferred in previous years, and are not reflective of current operating results. Adjusting for the aforementioned deferred compensation expenses (credits), selling, marketing and administrative expenses increased from $27,170 in second quarter 2021 to $32,367 in second quarter 2022, an increase of $5,197 or 19.1%; and selling, marketing and administrative expenses increased from $50,943 in first half 2021 to $64,776 in first half 2022 an increase of $13,833 or 27.2%. As a percentage of net product sales, adjusted selling, marketing and administrative expenses decreased from 23.7% in second quarter 2021 to 22.8% in second quarter 2022, a favorable decrease of 0.9 percentage points as a percent of net product sales, and adjusted selling, marketing and administrative expenses decreased from 23.5% in first half 2021 to 23.0% in first half 2022, a favorable decrease of 0.5 percentage points as a percent of net sales. The aforementioned more favorable expenses as a percentage of sales reflect the benefits of higher sales against certain expenses that are generally fixed and do not change significantly with changes in sales volumes.
Selling, marketing and administrative expenses include $14,156 and $12,437 for customer freight, delivery and warehousing expenses in second quarter 2022 and 2021, respectively, an increase of $1,719 or 13.8%, and $30,694 and $22,576 in first half 2022 and 2021, respectively, an increase of $8,118 or 36.0%. These expenses were 10.0% and 10.9% of net product sales in second quarter 2022 and 2021, respectively, and were 10.9% and 10.4% of net product sales in first half 2022 and 2021, respectively. The aforementioned increase in first half 2022 expense principally reflects increasing costs for over-the-road carriers relating to customer freight and delivery, including higher diesel fuel prices which are passed on to us in higher fuel surcharges. Labor shortages in the trucking industry have also are contributed to higher freight and delivery costs in first half 2022.
Earnings from operations were $26,978 in second quarter 2022 compared to $6,904 in second quarter 2021, and were $47,813 in first half 2022 compared to $17,314 in first half 2021. Earnings from operations include $(12,558) and $5,471 of certain deferred compensation expenses (credits) in second quarter 2022 and 2021, respectively, and include $(18,163) and $8,660 of certain deferred compensation expenses (credits) in first half 2022 and 2021, respectively, which is discussed above. Adjusting for these deferred compensation costs and expenses (credits), adjusted earnings from operations were $14,420 and $12,375 in second quarter 2022 and 2021, respectively, an increase of $2,045 or 16.5%; and adjusted operating earnings were $29,650 and $25,974 in first half 2022 and 2021, respectively, an increase of $3,676 or 14.2%. As a percentage of net product sales, these adjusted operating earnings were 10.1% and