Question: where is the best farming soil in the us and where did all the dirt come from
[{'answer': 'The Black Dirt Region', 'provenance': [{'wikipedia_id': '12953702', 'title': 'Black Dirt Region', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 21, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'from an ancient glacial lake bottom augmented by decades of past flooding of the Wallkill River'}, {'provenance': [{'wikipedia_id': '12953702', 'title': 'Black Dirt Region', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 322, 'bleu_score': 0.963949056609222, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 15090550998171448367}, 'section': 'Section::::Abstract.'}]}]