DuPont Pioneer is expanding once again in Johnston.

The Johnston-based seed company today will seek tax incentives from the Iowa Economic Development Authority (IEDA) for a $50 million expansion that will create an additional 100 jobs. 

The company plans to construct an additional 180,000-square-foot building for offices and laboratories, along with a 39,000-square-foot greenhouse facility. Construction of the new building will begin in the second quarter of 2013, and new employees would be added during a four-year period.

Pioneer is requesting $4.37 million in tax credits through the state’s High Quality Jobs Program from the IEDA board, which is scheduled to meet at 11 a.m. today.

The project will be the third expansion in Johnston by Pioneer in the past several years. In January, the company completed its new $40 million Beaver Creek facility on its campus, which includes space for approximately 400 research positions.

The company has also made a $32 million capital investment to remodel and double the size of its existing greenhouse facilities and add an insectary, a project that will add more than 100 full-time positions by the end of 2014.

“Our success in farmers’ fields has led to more jobs in our Iowa labs and around the world,” said Jane Slusark, a company spokeswoman. “We continue to see agriculture as a bright spot in today’s economy.”