By Dan Charles, NPR

We’d probably like to think that clean, safe food goes hand in hand with pristine nature, with lots of wildlife and clean water. But in the part of California that grows a lot of the country’s lettuce and spinach, these two goals have come into conflict.

Environmental advocates say a single-minded focus on food safety has forced growers of salad greens to strip vegetation from around their fields, harming wildlife and polluting streams and rivers.

The heart of this conflict is the Salinas Valley, on California’s central coast. And my guide to the valley, on this beautiful spring day, is Daniel Mountjoy, an ecologist with a nonprofit organization called Sustainable Conservation. “I just love the drive down through here,” Mountjoy says, as we head southeast from Castroville, the self-proclaimed “Artichoke Center of the World.”

We can see mountains to the east and the west, but the valley itself, miles wide, is as flat as high-tech field-leveling machines could make it. The Salinas River meanders down the middle of the valley, visible as a thicket of trees.

But most of what we see, though, is mile after mile of fields. Some are bare, ready for planting, others with rows of green leaves just emerging from brown dirt. This is one of the country’s biggest sources of fresh lettuce and spinach. It’s often called America’s salad bowl.

And for the past 40 years, this valley has been the scene of a struggle to find a balance between some of the most intensive farming in the world and what’s left of nature.

When Mountjoy first came here, as a student, almost 40 years ago, farming had already taken over.

“One of my professors brought us out on a field trip,” he recalls. This scientist had invented some of the first chemical herbicides that farmers used to kill off weeds. “He was very proud of the fact that farmers had been able to eliminate and restrict all noncrop vegetation from the farms, and pointed out that you could tell a good farm from a bad farm by that fact that, from fence post to fence post, the only thing that was growing was the crop.”

Mountjoy, though, found it bleak. Ecologically, it was impoverished. There was barely any food or shelter for insects, or the birds that feed on them, or bigger animals that need even more space.

Also, when it rained, soil and fertilizer washed straight into drainage ditches, streams, and the Monterey Bay.

Mountjoy became part of a movement to change that. He went to work for the Natural Resources Conservation Service of the U.S. Department of Agriculture. It’s the arm of the USDA that promotes environmental quality. And for almost 20 years, part of his job was encouraging farmers in this valley to create a greener, more diverse landscape.

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