Course Modules

Water Rights

Flood Irrigation

Drip Irrigation under black plastic

Drip Irrigation under white plastic

Holding Ponds

Drip Irrigation with fertilizer injection

Drip Irrigation with fertilizer

Furrow Irrigation

Ebb & Flood

Texas Water Policy

Clean Water

Major Aquifers

Minor Aquifers

Aquifer Pumpage

Watersheds in Texas

Assignment 8

Water Rights (and Responsibilities)

Learning Objectives

• Examine the role of water in horticultural crop production and landscape management.
  
• Read about the characteristics of different irrigation methods.
  
• Explore the ownership of surface and subsurface water.
  
• Study the legal framework for Texas water policy.
  
• Complete and submit Assignment #8.

Introduction
Water is the "universal growth regulator." Too much or too little at the wrong time in the cropping or growth cycle can be disastrous for horticultural crops. Access to a continuous supply of high quality water is an absolute imperative for horticultural production. Industrial and municipal water use will out-compete agriculture for water in the future.

Water Characteristics
Irrigated agriculture depends on several sources of water. Water can be withdrawn from flowing streams or rivers, provided by canals from major rivers, pumped from lakes and reservoirs formed by building dams on major rivers, pumped from lakes, ponds and tanks formed by collecting rainwater, and pumped from ground water.

"Water quality" generally refers to the presence or absence of dissolved substances that the water contains. Some of the substances of concern include:

• salts such as NaCl, and Ca, Mg carbonates;
  
• salts derived from fertilizers, including nitrates, phosphates, and sulfates;
  
• pesticides;
  
• heavy metals;
  
• fecal coliforms

Irrigation Methods
Irrigation has been practiced in various froms since the earliest days of crop production. The crop characteristics, availability of power, capital investment, and ability to manage technology must be considered when determining which technology will be used. Efficiency of water use varies drastically depending upon the system used.

flooding: levees are drawn around the area to be irrigated, and the area is flooded periodically to satisfy crop demands. furrow irrigation: crops are planted on ridges or beds in level fields, and water is flooded into the furrows between rows; subirrigation: drainage ditches are dammed and flooded so that irrigation water "backs up" into the drainage system and penetrates into root zone by capillary action; overhead irrigation: water under pressure is sprayed (sprinklers, irrigation gun,or center pivot) or dripped (LEPA (low energy precision application)) onto crops from overhead; micro-sprinklers: water under low pressure is sprayed from low volume emitters located at the base of trees or in containers; drip irrigation: water under low pressure is "leaked" from plastic tubes (T tape) or porus rubber tubes; fertilizer may be added (fertigation); subsurface drip irrigation: as in drip irrigation except the drip tubes are buried under rows within the root zone; hand watering; water is applied by worker using hose and hose-end water breaker; watering robot; water is applied in greenhouse by overhead boom fitted with coarse nozzles that traverses benches periodically; capillary matting: water is dripped onto water-retentive porus matting upon which pots are placed; pots take up water by capillary action; sand beds often used for same purpose in outdoor nursery container production; ebb and flood: greenhouse containers are placed in water proof trays fitted with drains; trays are flooded periodically (daily or every-other day), and pots take up water (and nutrients) by capillary action; after watering cycle, solution drains into storage tank where it is held until the next irrigation cycle;

Click on images to see larger view.

Factors Affecting Decisions on Irrigation Technology
The decision on which method to use is dependent upon many factors including:

1. cost of the technology (equipment and management intensity) relative to the cropping system;
   
2. availability of water;
   
3. water quality;
   
4. potential problems caused by leaf wetting;
   
5. leaching of contaminants into ground water;
   
6. skill of management required.
   Ebb & flood movie
   requires QuickTime.

Continue to Texas Water Policy section of module.

Continue to the Clean Water section of module.

Take the Irrigation Methods Sample Quiz

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