Plant nutrition

https://www.bhg.com/gardening/yard/soil/soil-amendments-nutrients/

Basic Nutrition in Plants

Plants need a balance of soil nutrients for healthy growth. Fertilizers, or complete plant foods, contain all of the basic macronutrients in soil: nitrogen, phosphorus, and potassium. Each chemical plays a vital role in plant development. For example, nitrogen promotes leaf and stem growth. Phosphorus encourages root growth, disease resistance, and flower color. Potassium assists in fruit and seed production. These nutrients are listed on packaged plant foods in percentages of N-P-K. If your soil is low in nutrients, don't fret. The following organic fertilizers, when added to soil, supply specific nutrients needed by plants.

Soil Nutrients: Nitrogen (N) Sources

• Alfalfa meal
• Blood meal (blood and bone)
• Composted manure
• Cottonseed meal
• Feather meal
• Fish meal or emulsion (Seasol)
• Mushroom compost
• Rice hulls

Soil Nutrients: Phosphorus (P) Sources

• Bat guano
• Bonemeal (blood and bone)
• Rock phosphate

Soil Nutrients: Potassium (K) Sources

• Dolomite lime
• Greensand
• Kelp meal
• Oyster-shell lime
• Rock dust
• Seaweed
• Wood ashes