Sunflower Army Ammunition Plant The Sunflower Army Ammunition Plant ( or SFAAP ) was a smokeless powder and propellant manufacturing facility in northwest Johnson County , Kansas , south of De Soto , owned by the United States Government and operated under contract , primarily by Hercules Aerospace Company . History . The Sunflower Army Ammunition Plant was originally known as the Sunflower Ordnance Works . Established in 1941 on 10 , 747 acres ( 43 . 492 km² ) , it was the world ' s largest smokeless powder plant . Although owned by the U . S . government , the plant was operated by the Hercules Powder Company under a contract signed on May 11 , 1942 . Construction then began immediately and was followed by the first production of propellant 10 months later . During World War II , the Sunflower Ordnance Works produced more than 200 million pounds ( 91 , 000 , 000 kg ) of propellants and employed as many as 12 , 067 people . Following the war , the plant was placed on partial standby . And in March 1947 , the contract with Hercules Powder Company expired . When the plant was placed on complete standby in June 1948 , the government took over maintenance and security . In 1951 , the Sunflower Ordnance Works was brought out of standby due to the Korean War . Once again , on June 30 , 1952 , the operation of the plant was contracted out to Hercules . This time the plant produced more than 166 million pounds ( 75 , 000 , 000 kg ) of propellants , with employment of up to 5 , 374 . The plant then went into standby again in June 1960 . The name of the plant was changed from the Sunflower Ordnance Works to Sunflower Army Ammunition Plant ( SFAAP ) on August 1 , 1963 . Two years later , on August 20 , 1965 , the plant was reactivated to aid the Vietnam War by producing in excess of 145 million pounds ( 66 , 000 , 000 kg ) of propellants before ceasing operations in June 1971 . While operating during this time , the plant employed up to 4 , 065 people . In 1972 , the plant was returned to standby status . A major facility modernization program was started in August 1967 . The program included the construction , between 1975 and 1979 , of a facility for the production of nitroguanidine . This facility was the first of its kind in North America and began production in 1984 and continued until 1992 , when the plant was again placed on standby . Nitroguanidine ( NQ ) is an essential component of triple - base gun propellant . In addition to being an oxidizer and energy carrier , it is loaded with hydrogen and this provides cooling in the gun tube which reduces the erosion rate of the tube metal so more rounds can be fired before refit . NQ was shipped out in fiberboard drums to another army facility where the triple - base is prepared , Alliant Techsystems won a contract on March 10 , 1995 to market the use of the Sunflower Army Ammunition Plant facilities . Also in February 1995 , the Environmental Protection Agency proposed that the site be placed on the National Priorities List , but it was never listed . Early in 1998 , SFAAP was declared excess by the U . S . Army , and the General Services Administration began the process of selling the site . As of October 1 , 2001 , the Army changed to a maintenance contractor and reduced the number of buildings used to an office building , an environmental laboratory , the old guard headquarters as a records repository , and the guard shack at the main gate .