The Hydrologic Cycle

Summary

• Water is a limited resource.

• Growers (farmers) have a responsibility to conserve water.

• Water can be conserved by capturing more water, using it more efficiently, and reducing consumptive use.

• Reduce, Reuse and Recycle Water

• Keep water clean

Water Quality

Pollution• Point sources

– Factories

– Sewage plants

– Manure storage

– Feedlots

Toxicity – everybody is responsible to prevent it

Water Quality (continued)

Pollution• Nonpoint sources

– Nutrients

– Pesticides

– Manure applications

Water Quality (continued)

Ways to avoid pollution:• Reduce runoff• Reduce erosion• Reduce fertilizer losses• Reduce pesticide use• Store and apply manure properly• Maintain wetlands• Practice drainage management• Install conservation buffers

Drainage and Irrigation

• Are tools to increase the productivity of land that is too wet or too dry

• More than 70% of world food are produce using I&D

• I&D strives to increase Water Productivity index of crop by increasing Irrigation efficiency.

Wetlands

• Areas that are wet long enough and often enough to support vegetation adapted to saturated soils are called “wetlands.”

• They have:– Hydric soils– Wetland hydrology– An environment that hosts wetland vegetation

Wetlands (continued)

Wetlands play a role in:• Water control• Water quality• Wildlife habitat• Recreation and education

Wet Soils

• Have fewer ecological functions than wetlands

• Make up 25% of farmland

• Are identified by:– Standing water– Presence of water-loving plants– Soil color – Percolation testing

Artificial Drainage

• Surface drainage– Collect excess water– Channel water away– Collect excess irrigation water

• Subsurface drainage– Collect water through underground pipes

Irrigation

Brings water to dry soils

Irrigation Systems

• Subsurface irrigation– Watering from below

• Surface irrigation– Border-strip irrigation– Furrow irrigation

Irrigation Systems (continued)

• Sprinkler irrigation– Hand-move irrigation– Solid-set irrigation– Traveling-gun irrigation– Center-pivot irrigation– Wheel-move irrigation

Irrigation Systems (continued)

Irrigation Systems (continued)

• Micro-irrigation– Drip irrigation– Micro-spray irrigation

Irrigate When

• 50–60% of available soil water has been used

• Soil moisture measurements indicate soil water is too low

• Evapotranspiration loss since last rain is high

• A set schedule is appropriate

Soil Moisture Can Be Judged By

• “Feel Test” and ribboning

• Potentiometer

• Evaporation pans

How Much Water?

Dictated by:• Soil texture• Rooting depth

Saving Water

• Use the most water-efficient system available

• Level land carefully

• Use well-designed systems to fit the soil, crop, and terrain

• Use sealed ditches

• Use measuring devices

Saving Water (continued)

• Use the correct amount of water

• Use the most efficient amount of water

• Schedule irrigation according to crop needs

• Use computers to automate systems

Water Quality

Considerations• Suspended solids• Boron• Soluble salts

Natural Moisture Regimes

Soil moisture conditions throughout a

growing season are considered when

implementing a natural moisture control

regime. These systems include:

• Xeric—dry

• Mesic—average

• Hydric—wet

Summary

• Drainage and irrigation can be used to increase soil productivity.

• Drainage takes excess moisture away; irrigation supplies water to dry areas.

• There are a variety of methods for both operations.

• The goal is to avoid water stress to plants.