Suburban Bancorporation reported yesterday second-quarter earnings of $3.3 million (74 cents a share), up 19.8 percent from $2.8 million (62 cents) a year ago.

For the first six months, income before securities transactions was $6.2 million ($1.38 a share) compared with $5.2 million ($1.16) a year ago.

Suburban Chairmna Robert Tardio said a 14 percent increase in average earning assets was a major factor in the increase in earnings. A bank holding company based in Hyattsville, Suburban operates Suburban Trust Co., the largest bank in the Maryland suburbs of Washington.

Maryland National Corp., holding company for the Maryland National Bank, the state's largest, reported second-quarter earnings of $5.4 million (75 cents a share) compared with $4.4 million (61 cents) a year ago.

First-half income before securities transactions increased 23 percent to $10.7 million ($1.50 a share) from $8.7 million ($1.22) a year ago.

Chairman Robert Harvey attributed the earnings increase to improved net interest income and a positive contribution from the corporation's non-bank subsidiaries, which include mortagage and realty companies.

First & Merchants Corp. reported its highest second-quarter earnings in more than three years. Income before securities transactions was $2.8 million (86 cents a share), an increase of 12 percent over the second quarter of 1977.

For the first-half, income before securities transactions increased 10 percent from a year ago to $5.1 million ($1.55 a share). F & M Chairman Coleman McGhee said increased net interest income was the major factor contributing to the improvement in earnings.

Rowe Furniture Corp. reported second-quarter earnings of $205,000 (9 cents a share) compared with a loss of $415,000 (17 cents) for the second-quarter in 1977.

For the six months, the Salem, Va. based manufacturer of medium-priced upholstery and occasional furniture reported earnings of $350,000 (15 cents a share) compared with a loss of $196,000 (8 cents) a year ago.

Chairman Gerard Birnbach said Rowe's segment of the furniture market "is plagued by excess capacity which is creating great competitive pressure" preventing the company from earning the higher profit margins of a few years ago.

American Furniture Co. of Martinsville, Va. reported yesterday a second-quarter profit of $413,410 on new sales of $16.6 million.

For the first-half earnings were $318,739 on sales of $30.6 million compared with $45,797 on sales of $26.2 million a year ago.

The Ryland Group Inc., based in Columbia, reported yesterday a drop in second-quarter earnings to $2.0 million (58 cents a share) from $2.3 million (68 cents) a year ago.

For the first-half, earnings dropped to $2.4 million, (72 cents a share from $3.1 million (93 cents a year ago).

Ryland Chairman James Ryan and President Robert Gaw said the volume and quality of the firm's backlogged orders should result in a substantially better second half.