United States Department of Agriculture - Agricultural Research Service
	Northwest Irrigation & Soils Research Lab,  Kimberly, ID
	Water and Nutrient Cycling

• Water is essential in the process of weathering primary minerals (rocks or geologic parent materials), transforming the minerals into secondary minerals (clays and silts), and dissolving mineral nutrients into the soil water solution.

 
• Water is the transport medium for nutrients absorbed by plant roots and transported throughout the plant tissues (transpiration).

 
• Water evaporation (transpiration) from the plant leaves helps cool the plant, similar to how perspiration (to sweat) does to humans.

 
• Almost all physiological processes in plants take place in the presence of water, and water is commonly the most limiting factor in plant growth.

 
• Water supplies the hydrogen which joins with the carbon dioxide to form sugar by the process of photosynthesis.

 
• Land plants (on average) require about 400 pounds of water for each pound of dry plant material produced.

 
• Water dissolves nutrients in decaying plant material and animal products and transports the nutrients into the soil to be recycled or when water runs off the land, into streams or lakes.

 
• Water also physically transports soil into water bodies. This is called erosion.

 
• When too many nutrients occur in water bodies, algae and aquatic plants may grow abundantly. In slow-moving water, as the algae and aquatic plants decay, oxygen can become limited to fish and other organisms. This natural process is call eutrophication.

 
• Hyper-eutrophication causes water to be unfit for drinking or swimming.

Last update on 17 April, 2001