Plants need water to grow. Irrigation means giving them that water instead of relying on rains, which might or might not come. With controlled amounts of water the plants are able to grow as much as possible.
crop rotation
cropping
To ensure you grow enough food for a year, plan your garden carefully, choose high-yield crops, rotate your crops, use proper fertilization and watering techniques, and consider preserving excess produce for later use.
high yield products from your local nursery has a specific product for this
Probably tobacco and sugar cane.
scientific research on increasing food supply ;)
In order to have healthy crops the Egyptians used irrigation techniques to water their crops. Irrigation is the artificial application of water to crops.
This stands for High Yield Variety, a crop cultivated using HYV seeds is called so.
Low-yield crops and a hilly terrain prevented major agriculture operations in Mexico until the 1950's when the Green Revolution allowed for high-yield crops and the establishment of mechanized farms.
Irrigation water has dissolved salts and minerals. Those salts and minerals are left behind as the water evaporates. Soil that is high in salt is not favorable for growing most crops.
Type your answer here... The Palous Area of Washington state is one of the highest yield in bushels per acre for non irrigated wheat crops.
Monoammonium phosphate (MAP) and diammonium phosphate (DAP) are two good examples.