Publications on the Center for Agriculture, Food and the Environment site.
Page with information on Management Guides - some are printed publications that can be ordered from the UMass Extension Bookstore; some are available online in part or in full.
Selected parts of the USDA:
The Commonwealth of Massachusetts, the U.S. Federal govenment and many international organizations (United Nations, etc.) publish reliable information on many topics. Here are a few relevant liinks to their websites.
See box below for US Department of Agriculture links.
Use science.gov to search federal governmental information for agriculture and allied areas.
Food & Agriculture Organization of the United Nations