Dividend investing is a tried-and-true strategy for generating strong, steady returns in economies both good and bad. But as corporate America's slew of dividend cuts and suspensions over the past few years has demonstrated, it's not enough simply to buy a high yield. You also need to make sure those payouts are sustainable.

Let's examine how Southern Co. (NYSE: SO) stacks up in four critical areas to determine whether it's a dividend dynamo or a disaster in the making.

1. Yield
First and foremost, dividend investors like a large yield. But if a yield gets too high, it may reflect investors' doubts about the payout's sustainability. If investors had confidence in the stock, they'd be buying it, driving up the share price and shrinking the yield.

Southern yields 4.8% -- moderate, but not necessarily cause for alarm.

2. Payout ratio
The payout ratio might be the most important metric for judging dividend sustainability. It compares the amount of money a company pays out in dividends to the amount it generates. A ratio that's too high -- say, greater than 80% of earnings -- indicates that the company may be stretching to make payouts it can't afford.

Southern's payout ratio is a fairly high 80%.

3. Balance sheet
The best dividend payers have the financial fortitude to fund growth and respond to whatever the economy and competitors throw at them. The interest coverage ratio indicates whether a company is having trouble meeting its interest payments -- any ratio less than five is a warning sign. Meanwhile, the debt-to-equity ratio is a good measure of a company's total debt burden.

Let's examine how Southern stacks up next to its peers:

Company

Debt-to-Equity Ratio

Interest Coverage Ratio

Southern

119%

        4 times

Exelon (NYSE: EXC)

97%

        6 times

Duke Energy (NYSE: DUK)

81%

        4 times

NextEra Energy (NYSE: NEE)

146%

        3 times

Source: Capital IQ, a division of Standard & Poor's.

Like many of its peers, Southern bears a fairly significant debt load, which it is able to bear in part because of the stability of the industry.

4. Growth
A large dividend is nice; a large growing dividend is even better. To support a growing dividend, we also want to see earnings growth.

Over the past five years, Southern has grown earnings per share by 2% annually and its dividend at a rate of 4%.

The Foolish bottom line
Because of its fairly high payout ratio, the key factor for Southern's dividend investors looking for income growth will be whether the company is able to improve earnings growth.

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Ilan Moscovitz doesn't own shares of any company mentioned. You can follow him on Twitter @TMFDada. The Motley Fool owns shares of NextEra Energy. Motley Fool newsletter services have recommended buying shares of Exelon and Southern Co. Motley Fool newsletter services have recommended creating a covered strangle position in Exelon. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.