Agriculture and Water  Humans depend on water in many ways, well
beyond the few liters needed daily for drinking. Water is also
essential for the production of food. Various forms of
agriculture, practiced on about half of Earth's land surface,
provide the vast majority of food that over 6 billion people
eat. Agriculture also provides much of the fiber for cotton,
wool, and linen clothing.  Rain-fed Agriculture  One of the
primary ways in which humans use water is by planting important
crops in places where they can capture natural rainfall as rain-
fed agriculture. Some forms of agriculture, such as intensive
rice and corn production, can be practiced only in rainy
climates. Such agricultural forms are much more productive than
others, such as cattle and sheep herding, which are usually
relegated to semiarid climates.  One of the primary reasons
rain-dependent forms of agriculture are more productive than
dry-land forms is that they have sufficient water to allow
plants to grow to their maximum potential. The