To familiarize yourself with key concepts related to Agricultural History, check out reference materials such as encyclopedias, dictionaries, and subject bibliographies. This will help orient you and narrow the scope of your research.
Here are a few dictionaries and encyclopedias on agriculture to orient you with various ideas and topics related to your research.
Encyclopedia of American Agricultural History by 
Encyclopedia of Rural America by 
Dictionary of AgricultureDictionary of Agriculture: From Zbaca to Zoonosis
Encyclopedia of Agricultural, Food, and Biological Engineering
Encyclopedia of Soil Science
American Horticultural Society Encyclopedia of Plants and Flowers
