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Water Needs for Horticultural Crop Production. Jim Shrefler, Extension Horticulture, OSU. Acknowledgement.
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Water Needs for Horticultural Crop Production Jim Shrefler, Extension Horticulture, OSU
Acknowledgement • This presentation was adapted from “Water Quantity and Quality Requirements for Agriculture” presented by Mr. Steve Upson, Horticulture Consultant, Samuel Roberts Noble Foundation, at the Agriculture Water Source Development Seminar held in Ardmore Oklahoma on August, 6, 2013.
Topics: • Crop water quantity considerations • Crop water quality considerations
A common question received by Agricultural Extension Agents and Consultants: ‘I want to grow (name the crop). Can you help me?’ If it is a horticultural crop, the response will often be: ‘Tell me about your irrigation source’.
The standard water application recommendation for crop production in Oklahoma is one acre inch per week. 1 acre = 43,560 sq ft 1 inch Volume equivalent = 27,000 gallons
Water in a Harvested Crop • How much water is in a watermelon crop • 30,000 lbs. of fruit per acre • 93% water • = 27900 lbs. of water • Water is 8 lbs. per gallon • 3487 = gallons of water
Why is water so important ? • Required for Photosynthesis • Mode of transport for mineral nutrients and photosynthate • Cools plant via transpiration
Factors determining amount of water to apply include: • Evapotranspiration rate • System efficiency • Rainfall
Seasonal Single Site Evapotranspiration (ET) Table - Ardmore, OK
Question: I’m having a well drilled on my property. The driller has informed me there isn’t much of an aquifer to draw from. What is the minimum yield a well needs to make to supply an irrigation system? Assumptions: • Well can be pumped continuously • Answer: 5 gallons per minute (gpm) per acre • 15 gallons per acre is a preferred minimum
Question: I have a one acre pond I want to use for irrigation. How many acres of pecan trees can I irrigate? Assumptions: • Annual requirement = 54 acre inches • Water from rainfall is not accounted for • 66% utilization rate • Avg. depth = 7 ft • Answer: 0.75 acres
Crop water quality issues: • Sand and silt • Organic particulate matter: weed seed, algae, etc. • Mineral precipitates/pH • Salinity
Crop Irrigation water salinity standards: • Ideal: 0-300 ppm TDS (total salts) • Good for most crops: 300-600 ppm • Caution: 600-1,000 ppm • Avoid: > 1,000 ppm total salts • Other measurements: Sodium, Chlorine, SAR
Ag Water Requirement Resources Classification of Irrigation Water Quality http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-2223/PSS-2401web.pdf Understanding Your Irrigation Water Test Report http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-4630/L-323.pdf Consider Pecan Trees' Water Needs During Drought http://www.noble.org/ag/horticulture/pecanwaterneeds Water is the Most Important Nutrient http://www.noble.org/ag/livestock/waterimportantnutrient Livestock Water Guidelines http://www.noble.org/ag/livestock/livestock-water-guidelines Agriculture Testing Services: Water Testing http://www.noble.org/ag/testing-services/water-testing
Summary: • Water requirements on the farm can vary in terms of quantity and quality needed. • Water sources may or may not be suitable for specific farm needs. • Understand these requirements before investing your time and money in purchasing a property or developing a water resource.