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Document Type

Thesis - University Access Only

Award Date

2008

Degree Name

Master of Science (MS)

Department

Agricultural and Biosystems Engineering

First Advisor

Hal D. Werner

Abstract

Competition for water is increasing while a growing world population requires more food production. Some irrigators are already faced with limited water supplies, particularly in poor years . It is critical to develop and implement efficient deficit irrigation strategies, and to predict the impacts of deficit irrigation on yield. South Dakota State University Management Software was used to simulate center pivot irrigation and com growth and yield at seven locations across the Great Plains. Sixteen to 24 years of weather data were used for each site. Thirty irrigation strategies were evaluated across three soil water holding capacities and three pumping rates. Evapotranspiration was calculated with the tall reference Penman-Monteith equation and dual crop coefficients for com. The yield ratio, calculated with a normalized transpiration ratio, was used along with water use data to evaluate irrigation strategies.
Strategies with high water use efficiencies performed well across all treatments and locations. The recommended maximum yield strategy is 30-60-30 (strategies were defined by the minimum available soil water (%) for early, middle, and late season). Using the recommended maximum yield strategy resulted in water savings and either increased or slightly decreased yields . Recommended deficit strategies are 15-50-0, 0- 30-0, and 0-15-0 for minimal, moderate, and severe water restrictions. Annual variation in yield is greatest when water is most limited. For deficit irrigation, the benefit of high water holding capacity soils may be limited to sites with frequent large rainfall events (>25 mm). Pumping rate had a small effect on the general yield-irrigation relationship, although limited pumping rates resulted in limited maximum yields for arid locations. Evapotranspiration forecasting was not found to be necessary for good irrigation management. Simulating irrigation and crop growth appears to be an effective way to evaluate deficit irrigation strategies.

Library of Congress Subject Headings

corn irrigation
deficit irrigation evaluation

Description

Includes bibliographical references (57-62)

Format

application/pdf

Number of Pages

106

Publisher

South Dakota State University

Rights

Copyright © 2008 Derek M. Heeren. All rights reserved

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