One of the more benign minerals miners go for is potash, which is a catch all term for mineral salts that contain the element potassium. Originally, potash was made by soaking ash in pots, and that’s how potassium got its name. So important is the mineral, that BHP Billiton Limited (ASX: BHP) is said to have earmarked it as a possible “fifth pillar” along with coal, oil, copper and iron ore.

1) 95% of the world’s potash is used in fertilizers, as plants need the chemical in order to grow. As farmland becomes more and more degraded due to hundreds of years of intensive farming, fertilizers become increasingly important. On top of that, climate change and environmental degradation are reducing the amount of arable land, all while the world population continues to grow, making it likely that our acute reliance on fertilizers will increase in the future.

2) Unlike the vast majority of smaller miners, giants like BHP and Rio Tinto Limited (ASX: RIO) can afford to take a long term outlook. BHP doesn’t see a particularly bright future for potash prices until the current oversupply shakes out, but anticipates there will be more demand than supply, from around 2020. That they are developing potash mines 5 – 10 years in advance of anticipated lack of supply, demonstrates the companies long term outlook.

3) BHP has already spent well over $1.2 billionon its Jansen project in Canada, which has the potential to become the world’s biggest potash mine, although it won’t be in production for some years yet. Potash is seen as a growth area, whereas coal is in decline. To quote BHP CEO Andrew McKenzie in 2013: “we’re probably finished for a time investing in coal.”

Like uranium, potash resources are far from scarce. That means that it will be the big companies that profit from the resource far more than the little ones, as efficiencies of scale will favour larger producers. On top of that, Reuters reports that potash producer Mosaic Co (NYSE: MOS) is laying off works due to falling prices for the mineral and that the company’s CEO, Jim Prokopanko said the market looked to be oversupplied for the next 3 years. However, there are some signs prices might be close to strengthening.

Either way, the ASX is littered with loss-making potash explorers, touting their potential and frequently raising capital from investors. Hopeful potash explorers include Highfield Resources Ltd(ASX: HFR), Reward Minerals Ltd (ASX: RWD), which has seen a director selling options on market, Potash West NL (ASX: PWN), which had less than $800,000 cash at the end of the March 2014 quarter, and more diversified explorers such as Rum Jungle Resources (ASX: RUM).

It’s clear in my mind that BHP is the best way to get exposure to potash, though I prefer resource companies like this one, positioned to profit fromthe impending gas boom, which should arrive earlier than the potash boom. In any event, small miners are unlikely to be successful, unless they have assets that are in high demand.