The problem of water

No matter how well the soil is cared for, with crop rotation and good fer­tilizers and protection against soil ero­sion, it still must have water or plants will not grow. Land without water is desert. Land with water is fertile. Even the Sahara Desert would be a rich farm­ing country if enough water could be supplied to it. Many parts of the world do not have enough rainfall during the year to grow the food the people need. Where there is plenty of rain, the climate is likely to be tropical and too hot for men's com­fort or health.

Even where there is nor­mally water enough for farming, a dry year, or drought, will come along now and then. This used to cause famine in big countries like China and India, where at best people hardly have enough to eat. Where nature does not supply enough water for farming, the problem can often be solved by irrigation. This is the bringing of water to farmlands from rivers or wells nearby. The oldest way of irrigating land is to dig ditches or trenches to carry water from a river or stream. They were doing this thousands of years ago in Egypt.

The great rice fields of China and other countries in the Orient are formed by irrigation. There are other ways of irrigating fields. Sometimes big pipes are laid on the ground, with holes punched in them every few inches. Water is pumped through the pipes, and as it flows through it sprays out of the holes and waters the fields. Another way is to drive a tank truck between the rows of plants, spraying them much as trucks sprinkle city streets—or the way you would water a garden with a watering can, except on a much larger scale. Many things we love to eat depend on a large supply of water. Tomatoes and oranges and lemons must be juicy to be good, and this means there has to be plenty of water for the plants to suck up. The government is constantly build­ing dams and aqueducts to store the water of rivers and carry it to the farms when it is needed.