Some farmers are pressing for changes to proposed agricultural rules aimed at protecting Lake Champlain, but environmental advocates told lawmakers that the rules don't go far enough. The required agriculture practices, which have been the subject of multiple meetings and public hearings, include rules for small farm certification, storing and managing manure, soil health and vegetated buffer zones on fields near water and ditches. The Legislative Committee on Administrative Rules is reviewing the rules to make sure they are not beyond the authority of the agency and not contrary to legislative intent, among other criteria. The committee on Thursday put off a vote until Nov. 17. The state agriculture agency says livestock farms and farms growing annual crops in flood plain areas will be most affected by the requirements. The requirements include increasing vegetated buffer widths on streams from 10 feet to 25 feet for small farms and creating 10-foot-wide vegetated buffers on field ditches for all farms. The required agricultural practices are part of Vermont's commitment to reduce phosphorus runoff into Lake Champlain, and agriculture is the state's biggest contributor at more than 40 percent, state officials said.