id	keyword
american_scientific_journal-2546	nitrogen
american_scientific_journal-2546	technology
american_scientific_journal-2546	production
american_scientific_journal-2546	energy
american_scientific_journal-2546	model
american_scientific_journal-2546	case
american_scientific_journal-2546	environmental
american_scientific_journal-2546	bio
american_scientific_journal-2546	research
american_scientific_journal-2546	economic
american_scientific_journal-2546	biomass