Chapter 6Chapter 6

Soil and the Soil and the Hydrologic CycleHydrologic Cycle

How does water move around How does water move around on this planet? on this planet?

97% of our world’s water is in the ocean97% of our world’s water is in the ocean our ground water only makes up another .7%our ground water only makes up another .7% of the .05% of the other water, 60% is in lakes of the .05% of the other water, 60% is in lakes

and 33% trapped in the soiland 33% trapped in the soil

How does water move around on How does water move around on this planet?this planet?

Most of the clouds are therefore formed form the Most of the clouds are therefore formed form the oceans by evaporation and transpiration oceans by evaporation and transpiration together these two avenues of water into the together these two avenues of water into the atmosphere are called evapotranspiration (ET).atmosphere are called evapotranspiration (ET). This rain then falls on areas we call watersheds This rain then falls on areas we call watersheds

usually defined as river area bounded by mountains usually defined as river area bounded by mountains or hills that divide the waters movement from one or hills that divide the waters movement from one another.another.

We utilize the Tuolumne River watershed with Don We utilize the Tuolumne River watershed with Don Pedro the primary storage site with Modesto and Pedro the primary storage site with Modesto and Turlock reservoirs the secondary storage site.Turlock reservoirs the secondary storage site.

How does water move around on How does water move around on this planet?this planet?

Reducing ET and EvaporationReducing ET and Evaporation Remove unwanted vegetationRemove unwanted vegetation Fallow periods for water replenishingFallow periods for water replenishing Vegetative mulches and crop residuesVegetative mulches and crop residues Plastic mulchesPlastic mulches ????

How does water move around on How does water move around on this planet? this planet?

Water infiltration and percolationWater infiltration and percolation If water does not move into the soil, then run-If water does not move into the soil, then run-

off occursoff occurs Water that is in the soil moves downward into Water that is in the soil moves downward into

least water potential area.least water potential area.• If the downward movement is impeded then the If the downward movement is impeded then the

water backs up until it forms a lake or moves into water backs up until it forms a lake or moves into another lower area.another lower area.

• Drainage can reclaim high water saturated areasDrainage can reclaim high water saturated areas Surface draining – Ditches and slopeSurface draining – Ditches and slope Sub-surface -Sub-surface -

DrainageDrainage

What do we do with What do we do with our tail water?our tail water?

What is the problem What is the problem with tail water?with tail water?

How does water move around on How does water move around on this planet? this planet?

Water infiltration and percolation (cont’d)Water infiltration and percolation (cont’d)• Water and the dissolved elements move with the Water and the dissolved elements move with the

water to lowest areawater to lowest area• Applications for septic tanksApplications for septic tanks

Enough percolation to have water move into the soilEnough percolation to have water move into the soil But not too fast as the soil cannot filter out the solids But not too fast as the soil cannot filter out the solids

(150cm per hour)(150cm per hour)

How does water move around on How does water move around on this planet? this planet?

Irrigation methodsIrrigation methods Water is getting scarcer and more people Water is getting scarcer and more people

want it we must use the present water in a want it we must use the present water in a more efficient manner.more efficient manner.

IrrigationIrrigation 1. How do we measure water?1. How do we measure water? 2. How do we decide what method to 2. How do we decide what method to

use?use? A. ClimateA. Climate B. Type of cropB. Type of crop C. Cost of water (availability)C. Cost of water (availability) D. Slope of fieldD. Slope of field E. Physical properties of soilE. Physical properties of soil F. Drainage capabilityF. Drainage capability G. Salinity or other problemsG. Salinity or other problems

IrrigationIrrigation

1. Flood1. Flood 2. Sprinkler2. Sprinkler 3. Drip3. Drip

Flood - TypesFlood - Types

1. Checks1. Checks 2. Furrow2. Furrow

A. Plastic or Alum. PipesA. Plastic or Alum. Pipes

B. Gated PipeB. Gated Pipe

C. Poly PipeC. Poly Pipe

D. Permanent pipe (valves)D. Permanent pipe (valves)

Sprinkler - TypesSprinkler - Types

1. Hand Set1. Hand Set 2. Permanent Set2. Permanent Set 3. Wheel Line3. Wheel Line 4. Center Pivot4. Center Pivot 5. Hose Drag5. Hose Drag

Drip - TypesDrip - Types

1. Micro Emitters1. Micro Emitters 2. In-Line Emitters2. In-Line Emitters 3. Adjustable Emitters3. Adjustable Emitters 4. Drip Tape4. Drip Tape 5. Many more types5. Many more types

Soil Moisture BehaviorSoil Moisture Behavior 1. Saturation (1/10 Atmosphere)1. Saturation (1/10 Atmosphere)

2. Field Moisture Capacity (1/3 2. Field Moisture Capacity (1/3 Atmosphere)Atmosphere)

3. Permanent Wilting Percentage (15 3. Permanent Wilting Percentage (15 Atmosphere)Atmosphere)

How does water enter the soil?How does water enter the soil?

through pores in the soilthrough pores in the soil sandy soils have the largest pores, but are sandy soils have the largest pores, but are

often filled with other materialoften filled with other material medium textured soils (loamy) have good medium textured soils (loamy) have good

water entry propertieswater entry properties clays, pores swell shut when they get wetclays, pores swell shut when they get wet

How does water move around on How does water move around on this planet? this planet?

Use of water for management of high salt Use of water for management of high salt soilssoils Perhaps improved drainage to remove excess Perhaps improved drainage to remove excess

waterwater Use more water to leach out the salts as long Use more water to leach out the salts as long

as there is a good clean source of water is as there is a good clean source of water is available.available.

Salt movement in soil.Salt movement in soil.

Salt movement in soil.Salt movement in soil.