-Which of the following is a source of human-fixed nitrogen?
I. industrially produced fertilizers
II. cultivation of soybeans
III. irrigation agriculture
A) only I
B) only II
C) only III
D) only II and III
E) only I and II

Question

-Which of the following is a source of human-fixed nitrogen?
I. industrially produced fertilizers
II. cultivation of soybeans
III. irrigation agriculture
A) only I 
B) only II 
C) only III 
D) only II and III 
E) only I and II

Quizplus · Accepted Answer

Industrially produced fertilizers are a direct source of human-fixed nitrogen, as they often contain nitrogen compounds that are synthesized through processes like the Haber-Bosch process. The cultivation of soybeans, and other legumes, involves symbiotic relationships with nitrogen-fixing bacteria, which convert atmospheric nitrogen into forms usable by plants, thus increasing the nitrogen content of the soil through biological means. Irrigation agriculture does not inherently fix nitrogen; it is a method of water application to crops and does not directly contribute to nitrogen fixation.

-Which of the Following Is a Source of Human-Fixed Nitrogen