Organic Agriculture Research Act of 2018 This bill amends the Food, Agriculture, Conservation, and Trade Act of 1990 to: (1) reauthorize through FY2023 the Organic Agriculture Research and Extension Initiative, and (2) increase mandatory funding for the program above the FY2018 level. (The program is administered by the Department of Agriculture and provides grants for research, education, and extension programs that enhance the ability of producers and processors who have adopted organic standards to grow and market organic agricultural products.)