Plants need space for their roots and leaves to spread out. When plants are crowded, they compete for water and sunlight and this can make them less healthy. If humans farm on Mars, there would be plenty of space. On Earth, the average temperature is 14 °C (57 °F), but here on Mars, the average temperature is -46 °C (-51 °F)! This is because Mars is 100 million km (62 million miles) further away from the warmth of the Sun. If humans farm on Mars, you would need to build greenhouses to keep the plants warm.
Since Mars is further from the Sun, the Sun shines with only 44% of the brightness you experience on Earth. This would reduce a plant’s ability to do photosynthesis. Photosynthesis is the process where plants convert sunlight, water, and carbon dioxide into sugar. If humans farm on Mars, you would need special lightbulbs to give the plants enough light. Plants need an atmosphere that contains carbon dioxide. During photosynthesis, plants use the carbon dioxide and water molecules to build sugar molecules. Luckily, Mars’ atmosphere contains enough carbon dioxide. But since the atmosphere is so cold, humans would need greenhouses to warm up Mars’ air.
Soil is made of mineral matter, like sand and clay, water, and organic matter. Organic matter is made by living things like earthworms and bacteria breaking down dead plants and animals. This process adds nutrients to the soil. Organic matter also allows the soil to hold water. But Martian dirt has no organic matter. To turn Martian dirt into Martian soil, humans would need to add fertilizer and compost.
How do we do that? Well, Cosmo is just about to tell you in the episode!