Usable forms of nitrogen can intentionally be increased in the soil by lightning.

Question

planting more trees.
planting fewer beans.
allowing organic matter to decompose.

Answer 1

Usable forms of nitrogen in the soil can be intentionally increased primarily by:

• Allowing organic matter to decompose.

Decomposing organic matter releases nitrogen in forms that plants can utilize, such as ammonium and nitrate.

While lightning does convert atmospheric nitrogen into usable forms through the formation of nitrates, it is a natural process and not a method that can be intentionally controlled for increasing soil nitrogen levels.

Planting more trees or fewer beans does not directly increase usable nitrogen in the soil as effectively as allowing organic matter to decompose. In fact, legumes (like beans) have the ability to fix atmospheric nitrogen, which can enhance soil nitrogen levels. Therefore, planting more beans can actually help increase nitrogen in the soil.