Research plot combines are designed for growers who produce small plots of numerous species or multiple accessions of widely used species. They are also widely used by researchers studying cultural practices for native species or conducting plant materials development programs. These combines have the same features as large grain combines except they are very narrow. They usually have special instrumented weighing systems to accurately record seed weight for each plot. They are designed for level cropland and should not be operated on rocky, rough, or sloping land.