Green manures usually perform multiple functions , that include soil improvement and soil protection : Leguminous green manures such as clover and vetch contain nitrogen-fixing symbiotic bacteria in root nodules that fix atmospheric nitrogen in a form that plants can use .

Green manures usually perform several functions , that include soil improvement and soil protection : Leguminous green manures such as clover contain nitrogen-fixing symbiotic bacteria in root nodules that fix atmospheric nitrogen in a form that plants can use .
