Past use of persistent organic pesticides, for example DDT and dieldrin, means that some agricultural soils are contaminated with chemical residues. In broadacre farming, these chemicals were used directly on soil or were applied to crops, contaminating soil via runoff or spray drift. Pesticide contamination might cause residues in stock or crops raised on affected land. Soil residue tests determine if pesticides are present and at what levels, so that the risk to livestock or crops can be assessed and remedial actions focused on affected areas. This primefact describes the pocess of sampling soils and sending them back to the laboratory to be tested for pesticide residues.