Soil Salinity and Sodicity

Salts are the bane of both irrigated agriculture and of civilizations that are based on irrigated agriculture, particularly if irrigation water and soil drainage are improperly managed. During the course of human history, thriving civilizations whose existence was based on irrigated agriculture have declined or disappeared, in part due to poor irrigation water management practices. For example, the Harappa civilization in the Indus Plain region of India and Pakistan, the inhabitants of the lower Viru Valley in Peru, and the Hohokam Indians in the Salt River region of Arizona have all succumbed to the degradative effects of soil salinization. However, nowhere in the recorded history of man is the influence of poor water management more graphically illustrated than in the desert region of the Middle East occupied by present day Iraq. The land between the Tigris and Euphrates Rivers in southern Iraq, known as the “cradle of civilization,” ancient Mesopotamia (“the land between the rivers”), or Sumer in ancient times, is now desolate and barren, consisting of saltencrusted soils. At one time (beginning over 6000 years ago) this region, a desert then as it is now, consisted of lush and productive fields of cereal grains, palm groves, and forage for livestock. The Sumerians colonized and transformed the desert by diverting water from the Euphrates River through a series of canals. They introduced irrigated agriculture to the region. The irrigation practices that were begun by the Sumerians continued under subsequent dynasties, such as the Akkadians and the Assyrians.