2 minute read


Nitrates, Phosphorus, Potassium, How Do Plants Obtain Minerals?, Helping Soil and Plants

Plants make most of their food by photosynthesis. But they also need minerals to be healthy. Plants cannot make minerals. They get them from the soil. Some of the minerals they need include the following:


Nitrates provide nitrogen. Nitrogen helps plants grow. All living cells contain nitrogen. Nitrogen is also part of chlorophyll, the pigment that traps sunlight. No nitrogen means no photosynthesis. You can tell if a plant does not have enough nitrogen. It will be small. Its older leaves will be yellow.

Food from the Sun Farmers spray fertilizers onto their crops. The fertilizers usually contain nitrates.

Food from the Sun Plants will not grow properly if they have certain mineral deficiencies. You can check the condition of the plant's leaves.


Phosphorus is important for photosynthesis, respiration, and growth. It encourages roots to grow well. You can tell if a plant does not have enough phosphorus. Its roots will be stunted. Its younger leaves will be purple.


Potassium helps chemicals called enzymes to work. Enzymes are needed in photosynthesis and respiration. Potassium can also protect a plant from disease. You can tell if a plant does not have enough potassium. Its leaves will be yellow. They will have dead parts on them.

Food from the Sun The soil in this field has been overused by a farmer. Crops may not grow well here unless the farmer adds fertilizer.

How Do Plants Obtain Minerals?

Plants get water through their roots. This is how they get minerals, too. From the roots, the minerals travel to the stems and leaves.

When plants die, the minerals go back to the soil. This keeps the soil rich. But sometimes a plant is part of a crop. Then it will be harvested by a farmer. This means that the minerals won't go back to the soil. Eventually, the soil is exhausted of minerals.

Helping Soil and Plants

But minerals can be added to soil to make it rich again. This can be done with fertilizers. Fertilizers can be natural or human-made. Natural fertilizers include manure, seaweed, and rock powders. Human-made fertilizers are mixtures of chemicals.


Some people will not eat plants that have been grown using artificial fertilizers. They think it is unhealthy. They eat only plants grown without any human-made chemicals. These plants are called organic.

Soil can also be improved by resting the land. The farmer does not grow any crops on a piece of land for a year. Or, different crops can be grown on the land in different years. Both ideas can repair the damaged soil.

Food from the Sun These people are harvesting seaweed. They will use it as a fertilizer for plants.

Additional topics

Science Encyclopedia for KidsFood from the Sun