Nutrients from the Soil Most living things need three basic things to survive: food, water, and air. If you said that plants get their nutrients and water from the soil, you are right! Although all green plants make their food by photosynthesis, they also need to get nutrients from the soil. The nutrients are formed in the humus. These dissolve in water and are taken up by the roots of the plant. The most important plant nutrients are nitrogen (N), phosphorous (P), and potassium (K). Nitrogen helps above-ground leafy growth and gives dark green color to leaves. Phosphorous encourages plant cell division. Without phosphorous, flowers and seeds could not form. Phosphorous also helps root growth and protects the plant from disease. Like phosphorous, potassium increases the plant's resistance to disease and encourages root growth. Potassium is needed for the making of chlorophyll. Now use your new knowledge to solve Mystery #2.