Exam 2

25% water 25% air 50% soil solids

-all pore space is filled with water -water will actively drain from soil due to gravity

-soil moisture that remains after excess water has drained -some small air pockets in pore spaces

-there is water in the soil, but it is so tightly adhered to soil particles that plants can’t access it

-as dry as the soil can get when exposed to air -a small amount of soil moisture remains

-no water left in soil -all pore spaces filled with air

-amount of water available to plants -AWHC= Field Capacity (FC) - Permanent Wilting Point (PWP)

-amount of water that exists in soil at a particular time -changes daily as plants take up water in their normal growth processes -may be measured as % water by mass, % water by volume, or inches of water per foot of soil

-amount of water that’s below field capacity -SMD=FC-SMC

-% varies by crop/situation -the percentage of available water holding capacity that management allows to be used up before irrigation

-the largest SMD is allowed to become before an irrigation -SMD max= AWHC x MAD

clay-highest soil water tension silt-moderate soil tension sand-low soil water tension

-hand move or wheel move sprinkler systems -furrows and border strips with long runs or sandy soils -specific plant requirements: moisture stress for almonds, citrus, cotton, wine grapes

-irrigation systems capable of small, frequent irrigations -irrigation with saline (salty) water -uncertain water supply -specific plant requirements: root crops (carrots, onions and potatoes), stone-fruit (cherries, peaches), strawberries and corn

Cohesion- water molecules are attracted to each other Adhesion- water molecules are attracted to others Capillary Action- when liquid flows through narrow spaces without external forces like gravity Polarity- unequal sharing of molecules

there is a limited amount of freshwater to accommodate to everyone’s needs

loss off water from evaporation from the surface of the soil or bodies of water

water pools on soil surface and gathers in bodies of water

water seeps into the ground

water stored in the ground

an area of land that channels rainfall, snowmelt, and runoff into a common body of water

a body of rock or sediment that holds groundwater

Irrigation

Domestic