Original: 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.
Simplified: 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.