The Agriculture Department has exempted a genetically engineered grass from federal regulation, a decision that some critics say could portend a loosening in oversight of biotech crops.

The department said that an herbicide-tolerant Kentucky bluegrass being developed by Scotts Miracle-Gro was not subject to federal regulation because its creation did not entail use of any plant pests.

The decision, issued late Friday, frees Scotts to sell the grass, which is meant for lawns, without federal approval. The company also does not need federal permits to conduct field trials, even though a different type of genetically engineered grass escaped from company test plots in the past and established itself in the wild.

The genetically engineered bluegrass contains a gene that allows it to tolerate the widely used herbicide Roundup, also known as glyphosate. That allows the chemical to be sprayed to kill weeds without harming the grass.