With the onset of frigid winter weather, the Iowa Department of Agriculture and Land Stewardship reported Thursday that the price of natural gas in Iowa rose 21 cent, ending the week at $4.53 MMbtu. Propane prices rose two cents compared to last week’s price with a statewide average of $1.96 per gallon. However, home heating oil fell six cents from last week’s figures, ending with a statewide average of $3.42. On the motor fuel side, the department said Tuesday’sprice for regular unleaded gasoline averaged $3.24 a gallon across Iowa — according to AAA. That was down two cents a gallon from last week and up 12 cents from one year ago. The national average on Tuesday was $3.31 per gallon, down two cents from last week’s price. Retail diesel fuel prices in Iowa were up two cents with a statewide average of $3.80 per gallon.