(Radio Iowa) A major upgrade is planned for the Koch Fertilizer plant near the Webster County town of Duncombe to boost ammonia production. The upgrades will boost yearly production by 85,000 tons. The work on the project will begin next year with completion by the fall of 2022. The cost of the project is estimated at $140 million. Koch officials did not say if there will be any new jobs with the upgrade. The plant has been in operation for over 50 years.