Precision Irrigation: An Opportunity for Dramatically Increasing

Agricultural Water Use Efficiency

George Vellidis

www.vellidis.org

Precipitation Map

Precipitation Map

Apr-Sept

Long term avg = 26 inches

2013 = 29 inches

2012 = 22 inches

2011 = 15 inches

2010 = 22 inches

2009 = 33 inches

Why Irrigate Crops?

• Increase yield/profit in low rainfall years

• Yield stability across years

• Safeguard investment (seed, tech fees, fertilizer, etc.)

• Risk management

• Pest control (pre-emerge and systemics)

• Optimize use of applied nutrients

Center Pivots in Georgia 2006

1970 – 8700 ac

87 center pivots

2013 > 1,300,000 ac >13,000 center pivots

The “Water Wars”

The “Water Wars”

• Oct 2013 - Florida Gov. Rick Scott and that state’s attorney general filed suit in U.S. Supreme Court claiming Georgia withdraws too much water from the Chattahoochee River system north of Lake Lanier to serve the growing Atlanta region.

• Also claim that irrigation withdrawals in the Lower Flint affect flows to Florida.

Why Precision Irrigation?

• Cannot realize benefits from variable rate fertilization, lime, seed, etc. if we do not first properly manage water.

• Research shows water is the most important crop input in many regions of the world.

• Water conservation and water use efficiency are critical issues.

• Already regulatory actions restrict agricultural water use.

• It is EXPENSIVE to irrigate.

• Total area = 228 ac

• Not cropped area = 84 ac (37%)

• 84 ac × 12 in irrigation = 1008 ac-in

► 27.3 million gallons / year

• 6000 pivots in the Lower Flint

Variable-Rate Irrigation

• Also called VRI or precision irrigation

• VRI refers to the application of different volumes or rates of water to different segments of a field

► rates are based on perceived or measured water requirements of sub-field zones

Variable-Rate Irrigation

• Sprinklers cycle on and off to meet target application rates

► for 100% rate, sprinklers on all the time

► for 50% rate, sprinklers on for 30s of every minute in 30s intervals

► on 30s – off 30s – on 30s ….

• Variable pivot speed

• Retrofits existing pivots

• Total area = 228 ac

• Not cropped area = 84 ac (37%)

• 84 ac × 12 in irrigation = 1008 ac-in

► 27.3 million gallons / year

• 6000 pivots in the Lower Flint

Agronomic Benefits?

Agronomic VRI Implementation

• 87 ac (35 ha) field

• Screven County Georgia

• VRI controls on all sprinklers and end gun

• Some zones require extra water

• 7.5% water savings

• or 1,420,000 gal (5400 m3) per year

► calculated using 8 irrigations of 1 inch (2,5 cm) as a base

University of Georgia Smart

Sensor Array (UGA SSA)

04/16/13

electronics

3 Watermark® sensors

The UGA SSA’s

flexible antenna

allows field vehicles

to pass directly over

the sensor node.

Sensor nodes of

commercially available

systems impede

tractors, sprayers, and

other field vehicles.

Gateway

Mesh Networks Used for Communication

Soil

water

tension at

8, 16, 24 in

Temp on

circuit

board,

ambient,

soil

Battery

volts,

life

Node number

Leary Fields

Colquitt Fields

Welcome to the University of Georgia SSA Data Portal Field 1

Corn

7 2

8

3

Can be changed to

account for climatic

forecast

see poster

Precipitation Forecasts

Emily Christ, Ga Tech Ph.D. student

Dr. George Vellidis, Professor

Crop and Soil Sciences Department

University of Georgia

2360 Rainwater Road

Tifton, GA 31793-5766

USA

office: +1.229.386.3442

mobile: +1.229.402.1278

email: yiorgos@uga.edu

www.vellidis.org