Which plants don't like nitrogen?

Certain plants, particularly legumes such as beans and peas, generally do not require or benefit from additional nitrogen fertilization; in fact, applying nitrogen to these plants can reduce their yield.

Why Legumes Don't Need Extra Nitrogen

Legumes possess a remarkable ability to produce their own nitrogen. This is due to a fascinating symbiotic relationship they form with specific bacteria, known as Rhizobia, found in the soil. These bacteria live in specialized structures on the plant's roots called nodules. Within these nodules, the Rhizobia convert atmospheric nitrogen (N2), which plants cannot directly use, into a usable form of nitrogen, a process called nitrogen fixation.

Because legumes are highly efficient at fixing their own nitrogen, external application of nitrogen fertilizer is often unnecessary. In fact, providing them with readily available nitrogen from external sources can sometimes inhibit their natural nitrogen-fixing process, leading to a counterproductive effect on their growth and productivity.

Impact of Nitrogen on Legumes

When nitrogen is applied to legumes, it can:

• Reduce Yields: The plant may divert energy from forming productive root nodules and focusing on flowering and fruiting towards absorbing the readily available nitrogen, which can lead to lower overall yields of vegetables like beans and peas.
• Inhibit Nitrogen Fixation: High levels of external nitrogen can signal to the plant that it doesn't need to maintain its symbiotic relationship with nitrogen-fixing bacteria, thus reducing or even stopping the vital process of nitrogen fixation.
• Promote Leafy Growth: While nitrogen is essential for leafy green growth in many plants, an excess in legumes can lead to abundant foliage at the expense of developing pods or beans.

Common Legumes That Dislike Added Nitrogen

It is generally recommended to avoid applying additional nitrogen to areas where legumes are planted. Here's a list of common legumes that typically do not require supplemental nitrogen:

• Beans:
  • Green Beans (Bush and Pole varieties)
  • Lima Beans
  • Soybeans
  • Fava Beans
  • Kidney Beans
  • Navy Beans
• Peas:
  • Garden Peas
  • Snap Peas
  • Snow Peas
  • Chickpeas (Garbanzo Beans)
• Other Legumes:
  • Lentils
  • Peanuts
  • Clover
  • Alfalfa

Understanding Nitrogen Needs

While legumes are unique in their nitrogen requirements, most other plants do benefit significantly from nitrogen, as it's a primary nutrient essential for vegetative growth, healthy leaf development, and photosynthesis. Always consider the specific needs of your plants and soil conditions before applying any fertilizer.