Webrat is assuming that your start_date field is a date select, which Rails implements as three drop downs: one each for day, month, and year. The "1i" postfix is how Rails manages to combine those three input fields into the single date attribute. This is called multipart parameter assignment; here's a good post about how this works and why: http://www.spacevatican.org/2008/12/3/dates-params-and-you

You'll have to tell Webrat that you're using a single text field as your start_date input element. I'm not sure how you do this, but I'm sure it's possible.