Question: what is the largest source of nitrogen on earth
[{'answer': "Earth 's atmosphere", 'provenance': [{'wikipedia_id': '59414', 'title': 'Nitrogen cycle', 'start_paragraph_id': 1, 'start_character': 400, 'end_paragraph_id': 1, 'end_character': 420, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '59414', 'title': 'Nitrogen cycle', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 634, 'bleu_score': 0.598102167989472, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 9155507699857878699}, 'section': 'Section::::Abstract.'}]}]