With crude oil prices soaring, shares in coal and fertilizer companies have also been climbing for the past year. Barron's offers a survey of the momentum plays, pointing out some opportunities and risks when investing in coal and fertilizer stocks.

Talking about risks, Barron's underlines the fact that it can be difficult for investors to put their hard earned money into a stock that is already trading near its highs. But as they say, the trend is up unless proven otherwise, and we might take this into account when picking our trades. For example, back in April, it looked like Mosaic Co. (NYSE: MOS) was facing technical weakness, but this did not last long and the company was able to rebound.

Now let's take a took at the coal sector. Data shows that the Dow Jones U.S. coal index gas gained more than 50% for the past year. While James River Coal Co. (NASDAQ: JRCC) has quadrupled this year, Peabody Energy Corp. (NYSE: BTU) has been seeing some weakness, and this might be a sign that the sector could face tough times ahead. The first concern tied to supply and demand appeared for Peabody when we began to notice that volume on rally days slipped, while volume on declining days has increased.