Gardeners often ask whether organic or inorganic fertilizers are better for plants. The truth is that plants don’t care whether the nutrients they receive are organic or inorganic as long as they receive their required 16 macro- and micronutrients in the appropriate amounts. The primary plant nutrients are nitrogen, phosphorus, potassium, calcium, magnesium and sulfur. The micronutrients are zinc, iron, manganese, boron, copper, molybdenum and chlorine. A plant acquires the final nutrients carbon, hydrogen and oxygen from the air and water.
Perhaps a better question than organic versus inorganic would be “is the soil a good medium for plant growth?” On a poor soil, no amount of fertilizer will supply plants with everything they need to grow and reproduce. A good soil has organic matter, which helps the chemicals in fertilizers exchange more efficiently through the roots of the plants. A thriving soil has a wide variety of living organisms in it such as insects, worms, beneficial fungi and bacteria. These critters break down the organic matter, which releases the nutrients to the plants. This increases the fertility level of the soil. Additionally, a soil loaded with organic matter allows better water infiltration, better water-holding capacity and protects soils from temperature extremes.
The more scientists study soils, the more they realize that feeding the soil rather than the plant is the key to plant health and success. Building up a soil for plant growth requires adding organic matter, not just inorganic fertilizer. Organic matter is one of the major keys to soil productivity and plant health. It consists of plant and animal residues in various stages of decomposition, living soil organisms and the substances created by these organisms..
Organic forms of nutrients come from living organisms. They are not necessarily more nutritious to plants than inorganic mineral fertilizers. Organic fertilizers are usually lower in nutrient value than inorganic ones, but are excellent at improving soil fertility. Again – feed the soil, not the plant. Inorganic sources contain only plant-available nutrients and therefore have no direct influence on soil structure or the presence of microorganisms. This is why agronomists generally consider it optimal to use both organic and inorganic sources together, a technique called Integrated Plant Nutrition Management (International Fertilizer Industry Association).
If you want a more flowers, fruit or vegetables, make sure you add compost and other organic matter to your soil each year. Organic or inorganic fertilizers can be used to augment soil fertility.