Research has been done to see where food waste occurred. The researchers looked at the food industry of the United States and found that food was wasted at the beginning of the food production. From planting, crops can be subjected to pest infestations and bad weather, which cause losses before harvest. Natural forces such as temperature and rainfall are the main influences on the growth of crops. For this reason, all forms of outdoor agriculture is subject to losses beecause of these influences. The use of machinery in harvesting can cause waste, as harvesters may be unable to discern between ripe and immature crops, or collect only part of a crop. Food is also wasted because it does not meet certain standards or regulations for quality and appearance As a result, certain crops that do not meet these standards are not harvested; left in the field, they can provide fertilizer, or food for animals.