Home player Carlota Ciganda had five kinds of lead to Stark before the final lap on the Los Naranjos track, a lead that did not shrink more than that Ciganda could win by four strokes before the Swede.
During the final round, Stark went 66 strokes, six under par.
For second place in the competition, she received the equivalent of SEK 559,000 in prize money.
The top five on the European Tour this year will get a place in the final qualifying round of the biggest golf tour for women, the LPGA.
Strong became six.
"Being so close to the top five hurts a little, that was my goal for the week.
I knew I had to win and I had nothing else in mind.
It was close but Carlota played very well, so I can not be sorry for that.
I will try again next year, says the 21-year-old in a press release.
"And not doing a single bogey on the last day when going for every stick, that's pretty good."
Stark became a professional this summer and this autumn took his first two victories as a professional.