Fertilizer isn't sexy. Fertilizer companies do not have the same luster and popular fascination that Tesla Motors and Apple have. Consequently, they aren't as commonly discussed (or traded) among casual investors. What Agrium (NYSE:AGU), CF Industries (NYSE:CF), Potash Corp (NYSE:POT) and other big fertilizer companies lack in broad appeal, however, is made up for with a consistent commodity market that equates to consistent earnings. Potash Corp and the other biggest fertilizer companies have the potential to grow, and they may be worth planting in your portfolio.

There is no love for fertilizer
In general, fertilizer does not see a lot of investment activity. Agrium and CF Industries are both big companies by most any definition, having respective market caps of $12.3 billion and $11.8 billion. Their average daily trading volumes hover around the 1 million mark. By comparison, smaller but flashier companies like First Solar see daily trading volumes nearly 4x greater. 'Sexier' large-cap companies like Tesla see daily volumes topping 10 million. A lot of analysis can go into trading volume, but from the simplest view, Agrium and CF Industries are just not that actively traded.

If the unwritten rule states that fertilizer companies can't be sexy, then Potash Corp is the clear exception to the rule.

Who can you love?
Commodity markets favor companies that produce the largest amount of the product at the lowest cost. Potash Corp is the biggest of the big fertilizer companies, and that alone makes it a considerable play in the sector. It provides one-fifth of the global supply of potash, a market that is projected to increase at a moderate 3.5% rate over the next few years.

Nonetheless, like its competitors in the field, Potash Corp has seen a big hit to its stock price in the past few months due to a complex set of issues including questions over corn prices, political uncertainty in Belarus and the US, and saturation of the fertilizer market, among other issues. All of these issues intermingle to affect potash sales.

As a result, Potash Corp recently lowered its third quarter guidance. What investors should not lose sight of are the general trends in earnings over the past several quarters, as well as the fact that third quarter earnings projections are still relatively positive at $0.41 per share. Combined with a generous dividend currently at 4.4% and an active share buyback program, Potash Corp is one of the safest players in the fertilizer market, regardless of short-term market conditions.

Agrium and CF Industries have seen similar declines in market value since the beginning of the year. Unlike with Potash Corp, the decline isn't as directly correlated to the Belarus debacle due to both companies having significantly less presence in the potash market. Agrium and CF Industries are more rooted in the North American market, which is more nitrogen- and phosphorous-based, as opposed to the more international potash market. In any case, both Agrium and CF Industries have followed Potash Corp's lead through the offering of dividends, while demonstrating consistent earnings and attractive earnings ratios in otherwise uncertain economic conditions.

The takeaway
While Potash Corp and other fertilizer companies may not be fodder for discussion around the proverbial water cooler, dependable earnings and strong dividends make all of these companies worthy of consideration to feed into your portfolio. Potash Corp, being the biggest of the bunch and having recently taken a hit in market value, makes a strong addition to most portfolios looking for steady, long-term returns.

Fool contributor Shamus Funk has no position in any stocks mentioned. The Motley Fool owns shares of CF Industries Holdings and PotashCorp. 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.