A consortium consisting of Hitachi Ltd. and nine other companies has found ways to eliminate harmful nitrate nitrogen from soil, officials of the companies said. Joint meeting with the University of Tsukuba in Ibaraki Prefecture, Japan has proved the effectiveness of the consortium's methods, the officials said. The substance is considered harmful when ingested in large quantities. A government environmental council this month recommended adding nitrate nitrogen to a list of toxic substances to be checked for when testing water quality.