14.1: Introduction
- Page ID
- 44677
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Microirrigation is a rapidly increasing method of irrigation, particularly for high value crops like vegetables and fruit and nut trees. A paramount question for a producer considering whether to invest in an expensive microirrigation system is whether or not the increase in crop production will be sufficient to pay for the system. A second concern is, Can the system be designed to filter the irrigation water to prevent the small emitters from clogging? Another important decision is which emitters, from the large array available, are appropriate for the intended purpose. Solving these issues will provide an excellent irrigation system for decades.
Microirrigation systems deliver water at low flow rates through various types of water applicators by a distribution system located on the soil surface, beneath the surface, or suspended above the ground. Water is applied as drops, tiny streams, or spray, through emitters, sprayers, or porous tubing and then flows through the soil by capillarity and gravity. Water pressure within the delivery lines is reduced by the design of the applicator to create a low discharge. Microirrigation is characterized by water being applied: (1) at low rates, (2) over prolonged periods of time, (3) at frequent intervals, (4) near or into the plant root zone, and (5) at relatively low pressure.
Most crops are adaptable to microirrigation. However, because the initial cost of these systems is high, microirrigation is best suited for high-valued crops, expensive land, or where environmental concerns are significant. Microirrigation systems are found on all soil types. These systems are particularly useful on very sandy and rocky soils that have a low water holding capacity or on salt-affected soils. Microirrigation is also excellent on steeply sloping land or where evaporation from the soil surface is a concern.
Potential advantages of microirrigation over other irrigation systems include: increased beneficial use of available water; enhanced plant growth, quality, and yield; reduced salinity hazards to plants; improved application of fertilizer and other chemicals; limited weed growth; decreased energy requirements; utilization of odd shaped areas; and improved cultural practices. Potential disadvantages include high initial costs, persistent maintenance requirements, restricted plant root development, and salt accumulation near plants (Bucks et al., 1982).
Microirrigation systems can be highly efficient and typically operate over prolonged periods of time; thus, low to moderate discharging water supplies can be utilized. This system offers maximum flexibility in chemigation. Frequent or nearly continuous application of plant nutrients, insecticides, fungicides, or other chemical amendments along with the irrigation water is feasible, and in most cases, beneficial for crop production. The low water discharge rates dictate a water applicator design with small openings; this can lead to clogging problems. Solutions to clogging include emitters that require less maintenance, adequate filtration of the water supply, and chemical treatment of the water.