Finding nutrition for plants on Mars will prove very difficult as the soil of Mars is composed of mostly minerals with high amounts of salts and sulfides. Although there are high amounts of those toxic minerals, there are also high amounts of nitrogen, phosphorus and potassium, the three main nutrients that plants require for growth. The air is also filled with carbon dioxide which enables photosynthesis. The only key ingredient for a healthy plant population is sunlight, which Mars has a distinct lack of due to the greater distance from the sun and dust storms that can last for months, making the sky a deep red, void of almost any light for long periods of time.