Keeping non-GM grain separate from GM grain is much like growing identity preserved grains. In this case, the non-GM grain is the grain whose identity we seek to preserve. Make a list of possible sources of mixing and take steps to avoid mixing. Good communication and good written records are imperative.
Consider harvesting non-GM crops first if maturity date allows. When harvesting non- GM crops in fields adjacent to GM crops also consider treating a few passes at the edge of these fields as though they were GM crops to reduce the possibility of harvesting grain cross-pollinated with GM stock.
Thoroughly clean the combine when switching from GM crops to non-GM crops. The grain tank is, of course, the area that comes to mind. Combined with the clean grain elevator, threshing system augers and gathering mechanisms, a combine can hold as much as two to three bushels of the previous crop.
Trucks and other crop transportation vehicles are typically the easiest link in the system to clean. Any hauling vehicle that includes augers, though, should be cleaned thoroughly. Grain receiving pits, augers or conveyors, elevator legs, dryers and bins are all possible sources of mixing. Clean in and around these parts of the system to minimize mixing. Run some non-GM grain at maximum capacity through the system to clean out and dilute GM grain to reduce mixing.
Remember that the potential for mixing occurs at every step in the process from planting to harvest and from storage to delivery. Keep samples of everything including the seed that went in the ground, samples of what has been harvested, and samples of what’s been delivered until you have all the documentation you need to know that the buyer is satisfied.
Inform all employees of the importance of preserving the identity of non-GM grain.
Consider labeling bins and delivery systems with permanent color-coded labels and
instructions to avoid mixing GM grain with non-GM grain. When two or more
completely separate storage systems are available, consider segregating grain by storage
site. On farms with systems large enough to duplicate many types of equipment, devote
duplicated equipment to either GM grain or non-GM grain.