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Irrigation water management 111012011501
This document outlines topics to be covered in a three-day course on irrigation water management for CNMP development. The course will cover determining the volume of water needed for crops including consumptive use, net irrigation requirements, and management allowed depletion. It will also discuss irrigation scheduling and the importance of considering crop, soil, climate and irrigation system factors. Finally, the document outlines three levels of conducting irrigation system evaluations for clients.
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Irrigation water management 111012011501
- 1. CNMP Development CourseNovember 16-18, 2004 Irrigation Water Management
- 2. CNMP Development CourseNovember 16-18, 2004 Irrigation Water Management • Irrigation Water Management is the process of determining and controlling the volume, frequency, and application rate of irrigation water in a planned, efficient manner.
- 3. CNMP Development CourseNovember 16-18, 2004 Irrigation Water Management • Why is Irrigation Water Management Important? – Manage soil moisture to promote desired crop response. – Optimize the use of available water supplies. – Minimize irrigation induced erosion. – Decrease non-point source pollution of surface and groundwater resources. – Manage salts in the crop root zone. – Manage air, soil or plant micro-climate.
- 4. CNMP Development CourseNovember 16-18, 2004 Irrigation Water Management • Minimum Documentation: – Crops to be Grown, Cropping Sequence and Soils Information. – Volume of Water Needed per Irrigation and for the season. – Application rate of irrigation water. – Records Showing Date and Amount of Water Applied. • Include type of irrigation scheduling technique used by the client. – Evaluation of the Irrigation System – Environmental Considerations
- 5. CNMP Development CourseNovember 16-18, 2004 Irrigation Water Management • Determining Volume of Water Needed
- 6. CNMP Development CourseNovember 16-18, 2004 Irrigation Water Management • Determining Volume of Water Needed – Crop Consumptive Use (CU) The amount of water used by the crop in transpiration and building of plant tissue, and that evaporated from adjacent soil or intercepted by plant foliage. It is expressed as depth in inches or as volume in acre inches per acre. It can represent the daily, design, monthly, or seasonal quantity of water needed for plant growth. Often referred to as Crop Evapotranspiration (ETc ).
- 7. CNMP Development CourseNovember 16-18, 2004 Irrigation Water Management • Determining Volume of Water Needed – Net Irrigation Water Requirements (Fn ) • Crop Evapotranspiration (ETc ). • Auxiliary water needs such as leaching, temperature modification and crop quality (Aw ). • Effective precipitation (Pe ). • Groundwater contribution (GW). • Change in soil water content for the period of consideration (ΔSW).
- 8. CNMP Development CourseNovember 16-18, 2004 Irrigation Water Management • Determining Volume of Water Needed – Net Irrigation Water Requirements (Fn ), Auxiliary Water Needs for Salinity Management • Soils in arid areas have the potential to become saline or sodic. • Saline or sodic soils will cause poor seed germination and reduced yields. • Additional water must be added to soils with a potential to have saline or sodic problems to leach excess salts. • Where the soluble salt content of wastewater is high enough to cause problems, the wastewater must be diluted with good quality water or applications must be limited.
- 9. CNMP Development CourseNovember 16-18, 2004 Irrigation Water Management MAD is defined as the percentage of the available soil water that can be depleted between irrigations without serious plant moisture stress. MAD is expressed as: – a percentage of the total Plant Available Water Capacity (AWC), – a soil-water deficit (SWD) in inches, or – an allowable soil-water tension level. • Determining Volume of Water Needed – Management Allowed Depletion (MAD)
- 10. CNMP Development CourseNovember 16-18, 2004 Irrigation Water Management • Irrigation Scheduling
- 11. CNMP Development CourseNovember 16-18, 2004 Irrigation Water Management • Irrigation Scheduling Important factors to keep in mind when developing a irrigation scheduling tool for a client: • The scheduling tool must consider information about the crop, soil, climate, irrigation system, water deliveries and management objectives. • An irrigation scheduling tool needs only be accurate enough to determine how much water to apply and when. • A good rule of thumb to follow when developing an irrigation scheduling tool is to keep it simple and easy for the client to understand.
- 12. CNMP Development CourseNovember 16-18, 2004 Irrigation Water Management • Irrigation System Evaluation
- 13. CNMP Development CourseNovember 16-18, 2004 Irrigation Water Management • Irrigation System Evaluation Irrigation system evaluation is the analysis of any irrigation system and management based on measurements taken in the field under normal conditions and management. There are three levels of irrigation system evaluations that can be performed: Simplified Abbreviated Detailed
- 14. CNMP Development CourseNovember 16-18, 2004 Irrigation Water Management • Irrigation System Evaluation There are 3 levels of Irrigation System Evaluations: Simplified – This type of evaluation provides enough information to the landowner/operator to make management and operation decisions. This evaluation usually takes a few hours to complete. Abbreviated – This type of evaluation provides enough information for the landowner/operator to make management and operation decisions plus identify any problems with the system. This evaluation takes a half to full day to complete. Detailed – This type of evaluation provides the landowner/ operator with a report and a comprehensive irrigation system operation and maintenance plan. This evaluation can take up to one to five days to complete.
- 15. CNMP Development CourseNovember 16-18, 2004 Irrigation Water Management • Learning Exercise Refer to the packet of materials in your course notebook for the learning exercise.
- 16. CNMP Development CourseNovember 16-18, 2004 Thank You!
Editor's Notes
- #2 CNMP Core Curriculum Speaker Notes : The student should become familiar with the basic concepts of irrigation water management and what is required for documentation. Required Course Materials : United States Department of Agriculture - Natural Resources Conservation Service. 1997. National Engineering Handbook, Part 652, Irrigation Guide, Chapter 9, Irrigation Water Management. Washington, D.C. Available at: www.info.usda.gov/CED/. Accessed 30 June 2004. United States Department of Agriculture - Natural Resources Conservation Service. 2004. National Statement of Work for Irrigation Water Management, Washington, D.C. Available at: www.nrcs.usda.gov/technical/standards/nhcp.html. Accessed 30 June 2004. Supplemental Resources : Local Irrigation District Water Management Plans and Irrigation Guides. United States Department of Agriculture - Natural Resources Conservation Service. 1997. National Engineering Handbook, Part 652, Irrigation Guide, Washington, D.C. Available at: www.info.usda.gov/CED/. Accessed 30 June 2004. United States Department of Agriculture - Natural Resources Conservation Service. 1997. National Engineering Handbook, Part 623, Irrigation, Section 15, Chapters 1 through 12, Washington, D.C. Available at: www.info.usda.gov/CED/. Accessed 30 June 2004. Suggested Learning Exercise : Provide the following information : Soil Name and physical soil properties table. Crop name, effective rooting depth, managed allowed deficit, and peak irrigation water requirement. Irrigation system efficiency and acres irrigated. At the end of the presentation have the students calculate total available soil water capacity, net irrigation water requirement, irrigation frequency, gross irrigation requirement and the required flowrate needed using the information provided.
- #3 CNMP Core Curriculum Speaker Notes : Present the definition of Irrigation Water Management shown on this slide to the students.
- #4 CNMP Core Curriculum Speaker Notes : Discuss why Irrigation Water Management is important when developing resource management plans.
- #5 CNMP Core Curriculum Speaker Notes : Discuss the minimum documentation requirements for Irrigation Water Management taken from the Statement of Work- Crops to be Grown, Cropping Sequence and Soils Information is to be obtained during the inventory process of developing the CNMP. Volume of Water Needed per Irrigation and for the season can also be obtained during the inventory process of developing the CNMP if there is good documentation available for the design of the irrigation system. Records Showing Date and Amount of Water Applied including the type of irrigation scheduling technique used by irrigator. If available this information will also be obtained during the inventory process of developing the CNMP. If this information is not available a record keeping system for irrigation scheduling will have to be developed for the landowner/operator. Evaluation of the Irrigation System should be done during the inventory process to develop the CNMP or for the design and application of irrigation water management as a single practice. Environmental Considerations are addressed during the inventory process for applying irrigation water management and are related to water quality, cultural resources and endangered plants and animals.
- #6 CNMP Core Curriculum Speaker Notes : This slide introduces section on how to determine the amount of water needed.
- #7 CNMP Core Curriculum Speaker Notes : Discuss the definition of Crop Consumptive Use (CU) as presented on this slide.
- #8 CNMP Core Curriculum Speaker Notes : Discuss the components of Net Irrigation Water Requirements as presented on this slide.
- #9 CNMP Core Curriculum Speaker Notes : Discuss the need to increase the net irrigation requirement for leaching excess salts. Saline Soil – This soil contains salts that provide an electrical conductivity of the soil-water extract, ECe of mor than 4.0 mmho/cm, and an exchangeable sodium percentage (ESP) of less than 15. The principal anions are cloride, sulfate, small amounts of bicarbonate, and occasionally some nitrate. Saline-Sodic Soil – This soil contains salts that provide an ECe of more than 4.0 mmhos/cm and an ESP or more than 15. It is difficult to leach because the clay colloids are dispersed. Nonsaline-sodic Soil – This soil contains stalts that provide an ECe of less than 4.0 mmho/cm and an ESP of more than 15. Soil with these characteristics are commonly referred to as “black alkali” or “slick spots”.
- #10 CNMP Core Curriculum Speaker Notes : Discuss the definition of the Management Allowed Depletion (MAD) presented on this slide. Mention that clay soils will store more water that sandy soils but do not release soil water as easily as sandy soils so the plant has to work harder to get water from clay soils. The objective is to allow the plant to extract water from the soil without causing it to work so hard to do so it does not produce the intended growth response.
- #11 CNMP Core Curriculum Speaker Notes : This slide presents the introduction to irrigation scheduling. Explain that irrigation scheduling involves monitoring soil-water content and/or crop water use.
- #12 CNMP Core Curriculum Speaker Notes : This slide presents important factors to keep in mind when developing an irrigation scheduling tool.
- #13 CNMP Core Curriculum Speaker Notes : This slide presents the introduction to Irrigation System Evaluations.
- #14 CNMP Core Curriculum Speaker Notes : This slide presents the basic definition of a irrigation system evaluation. Also presented are the three levels of irrigation system evaluations that can be performed. The simplified evaluation is the minimum requirement for designing the irrigation water management pracitice.
- #15 CNMP Core Curriculum Speaker Notes : This slide presents the definition of the three levels of irrigation evaluations that can be performed and the estimated time required for each level of evaluation.
- #16 CNMP Core Curriculum Speaker Notes : Present the learning exercise. This exercise should take approximately 15 minutes to complete.
- #17 CNMP Core Curriculum