|Special Technologies :: Good Agricultural Practices (GAP)|
GAP for Growers
A farmer who practices Good Agricultural Practices implements proactive food safety control measures to prevent crop contamination. GAP guidelines can be grouped into four categories; health and hygiene, water quality, soil supplements, and environmental hazards. A brief discussion of each is discussed.
Health and Hygiene – Growing fresh produce requires a significant amount of hand contact during harvesting, sorting, and packing. A worker who shows signs of diarrhea, vomiting, or sudden yellowing of the skin or eyes may have a disease that can be transmitted through food and should not handle fresh produce. Every food handler should wash his or her hands before starting work, after breaks, and especially after using the restroom. It may be difficult to provide the necessary sanitary facilities, but clean, accessible, and appropriately stocked restroom and hand washing stations are essential for preventing product contamination.
Water quality—Water has a many pre- and post-harvest uses for irrigation, pesticide application, washing harvested produce, cleaning harvest containers, and for drinking and hand washing. Food safety risks are greatest when surface water from ponds, streams, or rivers comes into contact with the edible parts of fruits and vegetables. Ground or well water is usually a safer choice, but it should be tested regularly and wells should be inspected to make sure they are intact and not located in areas that are subject to runoff during storms or floods. Municipal water is the safest source because you can be sure it has met government safety requirements. The choice of water to use and the level of risk is determined by the timing and application method. For instance, a safer source of water should be used as harvest time approaches or when overhead irrigation is used since the edible portions of the plant is likely to come into contact with the water just before harvest. Water used after harvesting should be free of human pathogens. If the safety of the water is in doubt, a sanitizer should be added to the water.
Soil supplements—Healthy soils contain abundant populations of microorganism and most are harmless to people. In fact, they are beneficial to crops because they break down organic matter into more readily available plant nutrients. However, when animal manure is used as a soil conditioner or a source of nutrients, contamination risks increase. It should be assumed that all raw manure contains microorganism that can make people sick. Therefore, proper manure management and application techniques are essential. If raw manure is applied to fields where fresh produce is grown, allow a minimum of 120 days between manure application and harvest. Working it into the soil in the fall of the previous year is even better since long term exposure to the elements greatly reduces pathogen levels. A better choice when using animal manures is to follow established aerobic composting techniques that will raise core temperatures to above 130oF for at least 5 days. Turn the pile several times to ensure even heat exposure to all parts of the pile. It is also important to store raw and incompletely composted manure as far away as possible from crop growing areas and to prevent runoff after heavy rains or flooding.
Field and Packinghouse Hazards—Farms and packing houses are by no means sterile environments and there are ample opportunities for contamination from harvest equipment and containers, harvest implements, packing equipment, storage facilities, and during transportation. Growers need to be aware of potential contamination sources from adjacent properties such as junk yards, toxic waste sites, and dairy or cattle operations and, to the extent possible, keep wild animals away from the crop. Harvest containers and totes should be cleaned before each use and stored so they are protected from sources of contamination.
The voluntary recommendations described above are applicable to all fresh produce growers. But growers who supply fresh produce to grocery stores and restaurants are increasingly being asked to supply documented evidence that GAP standards are being followed. An inspection from an independent third party auditor is typically required at some point during the harvest season.
There are resources available to those who have received certification notices from their wholesale buyers. A new United States Department of Agriculture audit service is available that is supported by funds from the Pennsylvania Department of Agriculture. Currently under development from Penn State Extension and the Department of Food Science is a training program that will help growers understand farm food safety risks and develop a food safety plan.