What are the two forms of nitrogen available for plant uptake?

The correct answer identifies ammonium and nitrate as the two key forms of nitrogen available for plant uptake. Ammonium (NH4+) is a positively charged ion that plants can directly absorb through their root systems. It is often found in fertilizers and soil as a result of decomposition and microbial activity.

Nitrate (NO3-), on the other hand, is a negatively charged ion that is highly mobile in the soil and is also readily absorbed by plants. Nitrate is formed through the process of nitrification, where soil bacteria convert ammonium into nitrate. This form of nitrogen is particularly important because it is the preferred nitrogen source for many plants, especially during the growing season when they require significant nutrients for growth and development.

Understanding these two forms helps in effectively managing soil nutrient levels to promote healthy plant growth, as both ammonium and nitrate have different roles and availability in the soil ecosystem.