Never mind the government regulators. When it comes to influencing the way farmers grow their crops, the real power someday may be Walmart, the nation’s largest food retailer.

Walmart pledges to double sales of locally grown food by 2015 and also is taking steps to ensure that all the food it sells is produced in sustainable ways. Walmart wants to measure and set farm-to-fork standards for the energy and natural resource impacts of food production.

 The company hasn’t been specific yet about what these initiatives will mean for farmers in Iowa. Work on the sustainability standards for domestically produced foods has just started.

But Walmart says it is interested in improving soil quality and conserving water and fossil fuels. In the run-up to announcing the plan last month, top Walmart executives flew into Iowa at least twice and toured three Iowa farms that either follow organic methods or are known for innovative environmental practices.

“They seemed to get it,” said Ron Rosmann, an organic farmer near Atlantic. He said the Walmart executives talked knowledgeably about hot-button issues such as antibiotic usage in livestock and the environmental benefits of organic practices. “They were saying this is what we need more of,” he said.