id	keyword
american_scientific_journal-4005	nitrogen
american_scientific_journal-4005	rainfall
american_scientific_journal-4005	soil
american_scientific_journal-4005	irrigation
american_scientific_journal-4005	fertilization
american_scientific_journal-4005	water
american_scientific_journal-4005	model
american_scientific_journal-4005	nitrates
american_scientific_journal-4005	class