ABSTRACT
There is no known record of the beginning of irrigated agriculture. It was most likely started on a very small scale by someone trying to keep a wilted plant alive by pouring water on the soil around its base. Then, ways were found to keep more plants supplied with water when they were remote from the water supply. However, carrying water from a spring or a stream to supply many plants is heavy work. By scraping small furrows from a stream to the plants, irrigation could be practiced with a greatly reduced labor input. The practitioners soon realized that they could produce more food by keeping an adequate supply of water available to their plants at all times. The availability of more food from irrigated plants meant that more people could live in a smaller area and communal living could be practiced. Communities could grow into cities and cities could grow into nations. When governments were organized, public resources were available to construct the necessary infrastructure to supply water to all suitable lands. It is certain that irrigation became a necessity as population increased in arid or semiarid areas. In many areas, the season of limited rainfall corresponds to the season of maturity of food crops. If the crops are short of water at that time, yields are severely depressed. It therefore became important to develop irrigation systems that could supply water to crops in seasons of rainfall shortage. With irrigation, it is possible to grow crops in areas of very low rainfall or areas where nearly all the precipitation falls in the non-growing season. Irrigation is a means of taking advantage of the productive capacity of suitably fertile soils which lack only adequate water for crop plants in their normal growing season.
