Nitrogen and Root Damage

Plants Need Nitrogen

• Nitrogen is an essential part of all living cells. Plants use nitrogen to form important proteins and enzymes. Without nitrogen, plants cannot make chlorophyll and, subsequently, cannot perform the metabolic process photosynthesis. A deficiency in nitrogen causes stunted growth, yellowed leaves that are small and that prematurely drop off, poor yields of fruits and seeds and an increased susceptibility to disease. However, excess nitrogen damages plants more than it helps them.

Root Damage

• Applying nitrogen fertilizer close to seeds or young seedlings damages the tender roots and kills the plants. Plants that manage to survive the damage from nitrogen in the root zone are often too damaged to take up any nutrients from the soil. Nitrogen fertilizers need water and time to break down into a plant-usable form of nitrogen that is safe for roots. To prevent root damage, apply nitrogen fertilizers a couple of weeks before planting, working the fertilizer into the soil and adding water to begin the nitrogen cycle. Do not put nitrogen directly on plant roots.

Other Damage

• Nitrogen deficiencies cause growth problems, but an excess of nitrogen causes more permanent damage. In carrots, overuse of nitrogen causes branching and hairy, fibrous roots. In tomatoes, it contributes to physiological leaf roll, blossom end rot and catfacing, which is a malformation of the blossom end of the fruit. In flowering plants, excess nitrogen causes a premature dropping of flower buds.

Environmental Damage

• Improperly applied nitrogen fertilizers cause damage to the environment. Irrigating at the time of application begins the nitrogen cycle, but overwatering causes surface nitrogen to run off into waterways and leaches soil nitrogen further into the soil and down into ground waters. This excess nitrogen causes an overgrowth of algae in lakes and streams. The algae deplete these waterways of oxygen, killing fish and other wildlife and upsetting the ecosystem.