Organic crops must be protected from potential contamination by adjoining conventional farms, as well as from non-organic fields in split operations. The drift and run-off of prohibited substances, as well as the pollen drift from GMO varieties, can compromise the farm’s organic certification status. The certifying agency can require water, soil, and plant testing in cases where contamination is suspected. Preventative strategies include the use of buffer zones and barriers, altering drainage patterns, posting “no spray” signs, and cooperating with neighboring conventional farmers. Growers with split operations must take additional steps to prevent the commingling of.