True or False: Ammonium nitrogen is generally available for plant uptake but does not accumulate in soil.

Ammonium nitrogen is indeed a form of nitrogen that plants can readily uptake. It is essential for various physiological processes in plants, including protein synthesis and growth. One of the key characteristics of ammonium nitrogen is that it is more stable and less mobile in the soil compared to other forms of nitrogen, such as nitrate. This stability allows it to be available for plant uptake, but it does tend to be converted to other forms of nitrogen through microbial processes.

While it is true that ammonium does not accumulate indefinitely in the soil due to its potential to be converted to nitrate or lost through processes like volatilization, it can still be present in the soil for a limited time. The statement suggests a complete non-accumulation, which aligns with the understanding that ammonium is only temporarily available in the soil system before being transformed or utilized by plants.

Therefore, this understanding of ammonium nitrogen's behavior in the soil and its availability for plant uptake supports the assertion that ammonium nitrogen is generally available for plant uptake but does not have the capacity for long-term accumulation, making the answer true.