An October 1 Baltimore Sun B’More Green blog post discusses new restrictions on applying fertilizers to lawns that took effect October 1.  The post also discusses the contention of one scientist that most lawns should not be fertilized at all.

The Fertilizer Use Act of 2011 restricts the nutrient content of all grass food sold in Maryland, barring phosphorus from most lawn-care products and setting limits on how much nitrogen should be applied. Though passed two years ago, its onset was delayed until now to give lawn-care companies time to train and certify their employees to meet new requirements.  …

But Tom Fisher, a professor at the University of Maryland Center for Environmental Science, challenges that premise. He argues that the best remedy for the bay would be to ban chemical lawn fertilizers altogether, except in very limited circumstances.  …

Fisher says studies show thick lawns do prevent sediment runoff better than scraggly yards, especially on slopes. But he says research also has found that nitrogen runs off fertilized lawns, in some cases at rates on par with runoff from farm fields.

“The devil’s in the details on this,” he said, “but there are lots of situations where fertilized lawns can lose as much nitrogen and phosphorus as a cornfield. So from the environmental perspective, that’s something we can’t afford right now.”

The post also reports that representatives from the lawn-care industry have challenged Professor Fisher’s assertions.