usable forms of nitrogen can intentionally be increased in the soil by..... A. allowing organic matter to decompose B. planting fewer beans C. lightning D. planting more trees
A. allowing organic matter to decompose
Usable forms of nitrogen can be increased in the soil through the process of decomposition. When organic matter such as dead plants, leaves, and animal wastes decompose, microbes break down the complex molecules into simpler compounds. Through this process, nitrogen is converted from organic forms to inorganic forms, such as ammonium (NH4+) and nitrate (NO3-), which plants can readily uptake and use for growth.
Lightning (C) can also fix atmospheric nitrogen into a form that plants can use, but it is not a process that can be intentionally controlled. Planting fewer beans (B) would not increase usable nitrogen; in fact, beans and other legumes actually help to increase soil nitrogen through their association with nitrogen-fixing bacteria. Planting more trees (D) can have various effects on soil nitrogen, depending on the type of trees and the existing soil conditions, but it is not the most direct method to intentionally increase available nitrogen in the soil through the decomposition process.