IAFNR Plant and Soil Sciences Module Soil Irrigation IAFNR Plant and Soil Sciences Module

What’s with Water? Covers ¾ of the earth’s surface Major part of the bodies of plants and animals Formed from two gasses, Hydrogen and Oxygen. H2O- two Hydrogen atoms and one Oxygen atom Exists in three forms Liquid- between 32º and 212º F Gas or Vapor- above 212º F Solid- below 32º F Universal Solvent Can dissolve almost everything Image retrieved from: http://gcdevelopmentllc.com/healthy_living

The Water Cycle The water cycle (or hydrologic cycle) describes the continuous movement of water throughout the surface of the earth and the atmosphere. As you can see from this diagram water also changes its form throughout the cycle. Image retrieved from: http://www.tutorvista.com/content/biology/biology-iv/ecosystem/water-cycle.php

Did you know water was responsible for these actions in plants?! Role Of Water in Plants Water performs vital functions in plants Necessary for all living plant cells and tissues Medium and solvent for nutrients in soil Chemical reactant for metabolic processes Like photosynthesis Responsible for stiffness in cell Function for stomata and cell expansion Coolant and Temperature buffer Did you know water was responsible for these actions in plants?!

Which classification of plants thrive in Do you Remember? Which classification of plants thrive in flooded conditions? dry conditions? Answers… Hydrophytes Xerophytes

Precipitation Water in the form of rain, snow, sleet, or hail Meteorologists use probabilities to indicate that degrees of confidence for precipitation to occur in a given area. Forecasts are important to management decisions for Planting Harvesting Irrigation

Water in Plants Water Loss Water Storage Water Movement Directly proportional to the surface area (leaf area) exposed to air Water passes in and out of leaves as vapor When plants lose more water than they bring in they wilt Plant adaptions and management practices to minimize loss Desert plant with small leaves Farmers fallow fields Water Storage Stored in soil Capillary water Used by plants and moves freely through the soil Water Movement Translocation- from soil through plant Transpiration- evaporation from leaf and plant surfaces Image retrieved from: http://gardeningunlimited.com/2013/07/12/am-i-over-watering-my-plants/

Water in Soil Evapotranspiration Percolation Irrigation Total water lost through evaporation from the soil surface and from transpiration through the plant Directly related to crop yields Percolation Movement of water through soil layers of material Irrigation Can provide the optimum amount of water for soils to avoid excess loss from Evapotranspiration Needs to be managed properly to avoid percolation

irrigation Irrigation Applying water to crops in such a way as to keep them wet but not too wet Optimal rainfall reduces the requirement for irrigation Used to ensure a productive crop Requires management and knowledge of precipitation and Evapotranspiration There are multiple methods of irrigation systems Selection depends on land slope, soil water intake, water holding capacity, water tolerance, and effect of wind Image retrieved from: http://texasbeautyscapes.com/irrigation/

Flood Irrigation Used where land is level Often used for orchards, vineyards, cereal grains Water enters through a head ditch and released into checks by siphons, gates, and valves. Image retrieved from: http://www.painetworks.com/previews/jp/jp0927.html

Furrow Irrigation Widely used method for crops Water runs down furrows between plant rows Water is more uniformly applied and allows for uniform maturity of crops Efficient, but very expensive Image retrieved from: http://luirig.altervista.org/naturaitaliana/viewpics.php?title=Level+furrow+irrigation+on+lettuce,+Yuma,+Az.

Sprinkler and Drip Systems Widely used method of irrigation Sprinkler Uses sprinklers on hand lines, wheel lines, and center pivots (see photo) Can be adjusted for water application rates, sprinkler spacing, and droplet size Drip Uses line source or point-source emitters Can be underground or on plant surface Image retrieved from: http://tlirr.com/products/center-pivot/ Image retrieved from: http://www.mzungudays.com/mzungudaysrevisited/chapters/sisterp.htm

Irrigation Efficiency and Timing 15% of irrigation water is lost to evaporation in sprinkler systems Drip systems are more efficient because they are not affected by evaporation Drip rated at 90% efficient Sprinkler at 75% Furrow system is very efficient, but also very expensive Timing To determine when irrigation is needed, manager needs to be aware of soil moisture Multiple ways to test for this Climate and precipitation

References Parker, R. (2010). Plant and Soil Science: Fundamentals and Applications. Clifton Park, NY: Delmar.