Andrew Ristvey The University of Maryland Extension programs are open to any person and will not discriminate against anyone because of race, age, sex, color, sexual orientation, physical or mental disability, religion, ancestry, national origin, marital status, genetic information, political affiliation, and gender identity or expression.
Making the Plant Happy Objectives for this topic include: What you should know before irrigating Water quality Water quantity Irrigation efficiency
Irrigation Water Quality It is essential to have your water tested!
Irrigation Water Quality Alkalinity is a measure of a water's capacity to neutralize acids is not a measure of calcium and magnesium that s Hardness
Irrigation Water Quality Alkalinity is a measure of a water's capacity to neutralize acids Major chemicals contributing to alkalinity: Bicarbonate ions (HCO3- ) calcium bicarbonate (Ca(HCO3)2) sodium bicarbonate (NaHCO3) magnesium bicarbonate (Mg(HCO3)2) Carbonate ions (CO3- - ) calcium carbonate (CaCO3)
High Alkalinity May cause a gradual increase in the growing media ph. It may be necessary to inject mineral acid (phosphoric or sulfuric) into the water or acidic media amendments, such as sulfur or acid-forming fertilizers, may be needed.
Low Alkalinity May be deficient in calcium, magnesium or sulfate and additional supplements may be needed. A fertilizer program that alternates a potentially basic fertilizer with a low potential acidity fertilizer can help prevent ph crashes in the growing media.
Other concerns of irrigation water quality Dissolved Micronutrients Check levels and assure that concentrations are below those indicated. If the water source does contain high concentrations of these micronutrients, adjustments in the fertilization program should be made to prevent an overabundance of the elements. Micronutrient toxicities are more probable when the ph of the substrate solution is low, rendering the micronutrients more available for plant uptake.
Other concerns of irrigation water quality Dissolved Micronutrients Capacity factor Aluminum (Al) Boron (B) Copper (Cu) Fluoride H (F - ) Iron I (Fe) Manganese (Mn) Upper limit for greenhouse use 0 to 5.0 ppm is normal range 0.5 ppm 0.2 ppm 1.0 ppm 0.2 to 4.0 ppm 1.0 ppm Molybdenum ---- Zinc (Zn) 0.3 ppm http://www.ces.ncsu.edu/depts/hort/hil//hil-557.html
Other concerns of irrigation water quality Dissolved Micronutrients Capacity factor Aluminum (Al) Boron (B) Copper (Cu) Fluoride H (F - ) Iron I (Fe) Manganese (Mn) Upper limit for greenhouse use 0 to 5.0 ppm is normal range 0.5 ppm 0.2 ppm 1.0 ppm 0.2 to 4.0 ppm 1.0 ppm Molybdenum ---- An important nutrient but too much is toxic Toxicity shows as orange-brown necrosis along the margins of older leaves Zinc (Zn) 0.3 ppm http://www.ces.ncsu.edu/depts/hort/hil//hil-557.html
Other concerns of irrigation water quality Dissolved Micronutrients Capacity factor Aluminum (Al) Boron (B) Copper (Cu) Fluoride H (F - ) Iron I (Fe) Manganese (Mn) Upper limit for greenhouse use 0 to 5.0 ppm is normal range 0.5 ppm 0.2 ppm 1.0 ppm 0.2 to 4.0 ppm 1.0 ppm Safe for most crops but toxic for many members of the lily family Molybdenum ---- Zinc (Zn) 0.3 ppm http://www.ces.ncsu.edu/depts/hort/hil//hil-557.html
Other concerns of irrigation water quality Dissolved Micronutrients Capacity factor Aluminum (Al) Boron (B) Copper (Cu) Fluoride H (F - ) Upper limit for greenhouse use 0 to 5.0 ppm is normal range 0.5 ppm 0.2 ppm 1.0 ppm Chamaedorea Chlorophytum Ctenanthe Dracaena Marantha Spathiphyllum Iron I (Fe) 0.2 to 4.0 ppm Manganese (Mn) 1.0 ppm Molybdenum ---- Zinc (Zn) 0.3 ppm Toxic levels of fluoride causes scorch of the tips of older leaves. http://www.ces.ncsu.edu/depts/hort/hil//hil-557.html
Other concerns of irrigation water quality Dissolved Micronutrients Capacity factor Aluminum (Al) Boron (B) Copper (Cu) Fluoride H (F - ) Iron I (Fe) Manganese (Mn) Upper limit for greenhouse use 0 to 5.0 ppm is normal range 0.5 ppm 0.2 ppm 1.0 ppm 0.2 to 4.0 ppm 1.0 ppm Molybdenum ---- Although 4 ppm is maximum for plants, even as little as 0.3 ppm can lead to iron rust stains on foliage if water is used for overhead irrigation Zinc (Zn) 0.3 ppm http://www.ces.ncsu.edu/depts/hort/hil//hil-557.html
We re good at knowing when to turn the water on
maybe not so much at knowing when to turn the water off.
Application Uniformity Check Catch cans - use 16 or more.
Do audit to sample application uniformity several places.
Application Uniformity Check
Application Uniformity Check Catch cans Irrigation Lateral Production Bed Hoop House, Flower Bed Must run all laterals that cover catch area.
Lower Quarter Distribution Uniformity, DU LQ List in descending order. Mark smallest quarter. Average of total and smallest 1/4. Sketch of laterals and sprinklers. Show catch cans and amounts of water. [Divide Average of ¼ by Average of total] x 100
Readings: (use 16, 20, 24 or more) 0.32 0.34 0.32 0.34 0.30 0.28 0.25 0.30 0.33 0.30 0.27 0.33 0.36 0.24 0.31 0.37 Total of all = 4.96 Average All= 0.31 Total small 1/4 = 1.04;Average 1/4 = 0.26 DU LQ = [0.26 / 0.31] x 100 = 84 %
Lower Quarter Distribution Uniformity, DU LQ List in descending order. Mark smallest quarter. Average of total and smallest 1/4. Sketch of laterals and sprinklers. Show catch cans and amounts of water. [Divide Average of ¼ by Average of total] x 100 [0.26/0.31] x100= 84%
Doing the Math easy! We calculate the Lower Quarter Distribution Uniformity, DU LQ DU LQ = [Avg of smaller 1/4 readings / Avg of all readings] x 100 Tells us how close the lowest (dry) readings are to all readings. Less than 70-75 percent is not so good.
Summary Correct pressure and nozzle/emitter flow rates are important factors in overall uniformity of a system. The Lower Quarter Uniformity Distribution gives us a measure of the uniformity of application.
Christiansen s Coefficient of Uniformity Determines the overall efficiency of an irrigation system
UC= [ 1-( Average deviation from the average volume of application) ] Overall average volume of Application x 100%
Reading Average Absolute DEV 0.32 0.31 0.01 0.30 0.31 0.01 0.33 0.31 0.02 0.36 0.31 0.05 0.34 0.31 0.03 0.28 0.31 0.03 0.30 0.31 0.01 0.24 0.31 0.07 0.32 0.31 0.01 0.28 0.31 0.03 0.27 0.31 0.04 0.31 0.31 0.00 0.34 0.31 0.03 0.30 0.31 0.01 0.33 0.31 0.02 0.37 0.31 0.06 0.31 0.43 Average = 0.31 Avg Abs Dev = 0.03 [1 (0.03/ 0.31)] x 100 X 100 UC = 99%
Christiansen s Coefficient of Uniformity For high value, shallow rooted or containerized crops, the UC value should be more than 87%. For field crops the UC should be higher than 81% Deep rooted orchard crops, the value should be greater than 72%
Check out your system soon
Gypsum blocks Tensiometers Wave propagation sensors Portable dielectric probes (PDP) Time domain reflectometry (TDR) Capacitance Probes
Tensiometers Determines soil moisture status Can tell you when to turn water on and off Relatively inexpesive Should only be used for soils
Capacitance probes Determines soil moisture content Can tell you when to turn water on and off Can be used for soils and substrates Systems can be expensive
Questions? Contact me Andrew Ristvey aristvey@umd.edu