15: Chemigation
- Page ID
- 44311
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)- 15.1: Introduction
- This page discusses chemigation, the injection of chemicals into irrigation water for uniform application of fertilizers and pesticides. Benefits include timely use and reduced contamination, but risks involve potential water source contamination and human exposure. Safe practices require non-corrosive materials and regulatory compliance to prevent backflow.
- 15.2: Chemical Injection Pumps
- To inject chemical solutions into a pressurized irrigation water stream requires the following equipment components: An injection pump, a chemical supply tank, injection tubing and associated valves, and calibration devices. There are three main types of pumps that are commonly used for chemical injection: piston, diaphragm, and venturi injectors.
- 15.3: Backflow Prevention and Other Safety Devices
- With chemigation a primary concern is chemical contamination of the irrigation water source due to backflow of the water chemical mixture in the irrigation pipeline and/or the flow of concentrated chemical from the supply tank to the water source. Another important matter is soil contamination with concentrated chemical in the injection area.
- 15.4: Management of Chemigation Systems
- Avoiding chemigation when wind speeds are high will help with uniform sprinkler applications and avoid drift onto non-target areas such as roads and areas with high public use. Two key management requirements are calibration of the injection system and flushing the injection and irrigation systems following chemigation events.
- 15.5: Summary
- Chemigation is the practice of applying chemicals with irrigation systems. The chemicals, which include fertilizers, pesticides, and system maintenance chemicals, are mixed with the irrigation water for application. The chemicals are often injected into the irrigation water stream with a pump, but in small-scale systems chemicals can be mixed with the water in the water supply tank.
- 15.6: Questions
- Locate the label of a herbicide and a insecticide that are approved for chemigation. Are the backflow prevention equipment requirements the same on each label? Can the products be legally applied in irrigation systems that are connected to a public water supply system? Explain what it means to have a flow proportional injection system and under what conditions or situations would it be useful to use a flow proportional injection system.
- 15.7: References
- ASABE Standards. (2018). ASAE EP409.1 MAR 1989 (R2018): Safety devices for chemigation. St. Joseph, MI: ASABE. AWWA. (2015). Backflow prevention and cross-connection control, recommended practices. Manual of water supply practices M14 (4th ed.). American Water Works Association. Buttermore, G. W., & Eisenhauer, D. E. (1989). Calculation of chemical flushing times in center pivot irrigation systems. Trans. ASAE, 32(4), 1193-1196. DeTar, W. R. (1983). Travel time for chemicals in an irrigation sys