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.

Water Quantity and Quality Requirements for Agriculture

Crop water quantity considerations Crop water quality considerations Topics: Crop water quantity considerations Crop water quality considerations 4

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’.

Why is the water resource so important?

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 Date Short Crop ET (in) Tall Crop ET (in) Cool Season Grass ET (in) Warm Season Grass ET (in) Pan Evaporation (in) 08-02-13 0.31 0.41 0.29 0.19 0.42 08-01-13 0.24 0.22 0.15 0.30 07-31-13 0.25 0.21 0.14 0.27 07-30-13 0.28 07-29-13 0.17 0.12 07-28-13 0.23 07-27-13 0.20 Total 1.61 1.97 1.50 1.00 2.05

Question: I’m having a well drilled on my property 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

Pecan Water Requirements Height Age (years) Volume (gallons/day) Less than 5’ 1-3 1 – 4 5’ 3 – 5 2 – 5 10’ 4 – 7 3 – 7 15’ 6 – 8 7 – 10 20’ 8 – 10 13 – 17 25’ 10 – 12 21 – 27 30’ 12 – 13 31 – 39 35’ 15 42 – 53 40’ 25 55 – 70 50’ 40 86 – 108 60’ 50 + 125 - 155

Question: I have a one acre pond I want to use for irrigation 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

Ideal: 0-300 ppm TDS (total salts) Good for most crops: 300-600 ppm 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

Water sources may or may not be suitable for specific farm needs. 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. 20