1. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Unit 38 Irrigation Technology

2. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Benefits of Irrigation Water can be added to supplement precipitation Water can be added when precipitation does not fulfill the crop’s needs Plant nutrients can be added to the water Pesticides can be added Can reduce frost damage Can be used to distribute liquid manure Can cool crops on excessively hot days

3. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Considerations Before investing in the high cost of irrigation, you must consider –profits from normal precipitation –yields from irrigation –what you can afford –energy requirements –sufficient time, labor, and management expertise –risks –sufficient water supply –suitable soil –possible problems –consult a system designer

4. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Water Requirements Acre inch: basic measurement of irrigation water use; the amount of water needed to cover 1 acre of land with 1 inch of water Without runoff, it takes 27,000 gallons to cover 1 acre with 1 inch of water To meet the possible demands, a system must be able to supply peak-use demands every day for an extended period of time

5. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Sources Sources of irrigation water –streams –rivers –lakes –ponds –reservoirs –irrigation district pipes or canals –deep wells

6. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Irrigation Systems Surface irrigation: adding water to the soil surface by means of gravity –methods: flooding or furrows Sub-irrigation: addition of water to soil below the surface –methods: open ditch or perforated pipes Trickle: application of water onto or below the surface of soil through small tubes or pipes –works well for individual plants and container-grown plants

7. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Irrigation Systems (continued) Sprinkler: dispersion of water in droplets to simulate rain –Sprinkler heads spread water droplets evenly over the soil –Good for golf courses, nurseries, field crops, vegetables, and orchards

8. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. System Management Apply water in accordance with crop needs –Remember that peak demand will occur when crops are growing quickly and producing seed Place water where it will be most useful Only use water when needed Use moisture sensors

9. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Important Terms Transpiration: release of water through leaves Precipitation: rain or snow Irrigation: human-controlled watering systems Pesticide: substance to control pests Seasonal demand: amount of acre inches of water required by a crop Emitters: nozzles that release water

10. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Important Terms (continued) Wetted zones: small or locally watered areas Humidistat: measures humidity in air Solenoid valve: actuated by an electromagnet Sprinkler heads: break water into droplets Moisture sensors: placed in soil to indicate moisture content Tensiometer: a type of moisture sensor