Plants obtain the nitrogen they need primarily from the soil through their roots.
Nitrogen Acquisition by Plants
Plants don't directly absorb nitrogen gas from the atmosphere like some bacteria do. Instead, they take up nitrogen from the soil in two forms:
- Ammonium ions (NH₄⁺): Although plants can absorb ammonium, it's not the dominant form in most agricultural soils.
- Nitrate ions (NO₃⁻): This is the main form of nitrogen absorbed by plants in agricultural soils due to the process of nitrification.
How Nitrate Gets to Roots
- Nitrification: This process is common in agricultural soils, where microbes convert ammonium into nitrate. This leads to nitrate being the most abundant available form of nitrogen.
- Water Movement: Nitrate is water-soluble, meaning it moves freely with water toward plant roots as they absorb water.
Understanding the Process in Detail
| Form of Nitrogen | How it's Absorbed | Importance |
|---|---|---|
| Ammonium (NH₄⁺) | Absorbed by roots | Available, but less dominant in agricultural soils |
| Nitrate (NO₃⁻) | Absorbed by roots | Primary source of nitrogen for plants due to nitrification and mobility in soil water. |
Key takeaways:
- Plants rely heavily on nitrogen for growth, using it to make essential compounds like chlorophyll and proteins.
- Nitrate is the form of nitrogen most often utilized by plants, due to its mobility in the soil, despite plants being able to absorb ammonium.
