Waste
Agriculture in the United States accounts for approximately 80% of the Nation's consumptive water use. This is an astronomically high number which translates into one of the most energy intensive industries in the world today.
Despite that large energy investment, the USDA estimates that Americans waste around 27% of their food (and some sources estimate that the number is closer to 40%). This waste translates into approximately 350 million barrels of oil just being discarded, a large number by any calculation.
Solutions
One solution to the large amount of food waste is to simply be more efficient in your food purchasing and consumption. By not eating excessive amounts of food and planning your grocery shopping trips better, you can avoid bringing home more food than you could eat. This will not only reduce wasted food and help the environment, but it will also save you money.
Composting - Composting is a wonderful alternative to throwing food you will not be eating into the garbage. Compost loosens clay soils and helps sandy soils retain water. Adding compost improves soil fertility and stimulates healthy root development in plants. The organic matter provided in compost provides food for microorganisms, which keeps the soil in a healthy, balanced condition. You cannot compost everything (such as meat and dairy products), but you can return a great deal of kitchen waste directly into the environment instead of sending it to a landfill.
Resources
EPA - The EPA's guide to composting.
Compost 101 - Another source of information for those looking to start a compost bin.