Sub-surface Drip Irrigation and Modern Agriculture

Elliott W. RoundsApril 18, 2008

SOIL 4213

Outline

• Introduction– What is SDI– Benefits– Disadvantages– Design– Cost

• Research results– Rice work in Beaumont, TX

• Other equipment

Introduction

What is SDI?• Subsurface Drip Irrigation• Irrigation system where

water is supplied to roots only

• System is buried beneath the soil surface

Why SDI• Reduction in total water

used• Nearly zero evaporation

– Lower evapotranspiration• Large cities looking for

sources of fresh water– Beginning to buy water

normally designated for agricultural use

Benefits of SDI

• Increased Water Use Efficiency (WUE)– WUE = (total DM

produced/total water consumed)

• Increased yield and quality– Reduced stress– Constant water in

rooting zone

• Lower energy required– Pressures lower

• Reduced non-beneficial use– Less soil volume watered– Little evaporation and

run off• Reduced deep

percolation

Benefits of SDI• Increased cultural

practices– Field remains dry– Ability to apply

agrochemicals during irrigation• Pivot systems must turn off

irrigation and apply after field dries or aerial

– Weed control increased • Small fraction of soil

watered• Most weed seeds on surface

• Able to use other water sources– Saline water

• Soil water more diluted• Salts move beyond active plant

root zone• Inappropriate water/seed

placement could increase salt stress by moving salt into root zone

– Biological effluent– Treated waste water– Pathogens and toxins in water

should be addressed before use

Benefits of SDI

• Improved chemical application– Fertilizer application• Increased fertilizer use efficiency

– Reduced leaching and runoff• Makes the environmental wackos happy

– Reduced cost because not driving applicator rig across field at a cost of >$3.00/gal of diesel

Disadvantages of SDI• High costs

– Installation, operation and maintenance largest constraint– USDA programs to help – Environmental Quality Incentive Program (EQIP)

• High maintenance– 1° - emitter clogging– 2° - leaks caused by animals, personal or machinery

• Salt accumulation near plants– In arid environments the salts are not moved out of root zone by rain fall

• Restricted root growth– Root growth can be limited to the zone

• Restricted crop rotation– Row direction (orientation) and spacing set – Can not be changed

• Can not catch up if water demand increases– Constant watering of root zone– Volume of water pumped is much lower compared to pivot system

Schematic

SDI Design

Installation • Most common system

– 80” tape spacing– 7/8” tape– 27” emitters

• Cost– Eco-Drip custom designs for

each field• No cookie cutter designs

– Average range is $150-250/ac

– USDA programs available• Most are 50% cost share

80” tape spacing in cottonPlace the tape in the middle of every other row

Research Results

• Does SDI work?• A lot of work done in dryland crops– Cotton, corn and soybeans

• Rice – high demand for water because rice is flooded• Lower Colorado River Authority (LCRA) instituted

research with Texas A&M University Agrilife Research and Extension Center at Beaumont to look at SDI in rice production– Study by Dr. Ted Wilson and Jim Medley

Water Use

0

5

10

15

20

25

30

35

1-Mar 21-Mar 10-Apr 30-Apr 20-May 9-Jun

Date

Wate

r App

lied (

inche

s)

Flooded PlotsDrip Irrigated Plots

PermanentFlood

• Water Savings – Drip tape plots compared

to the flooded plots• 2002 – 55%• 2003 – 47%• 2006 – 48%

Permanent Flood

Date

Yield

• No difference between flood and drip tape

• In the drip tape plots– Significant difference

observed between the tape and above the tape

Other Considerations• Auto-steer (RTK)

– Not essential but helps– Mostly important because

of seed placement not damage to system

– Tech Research Farm kid was working ground and tore up system

• RTK Needs– Base station (signal)– Hydraulic steering– Guidance package

• RTK Cost– Base station

• $10,000 plus cost of structure

• Only 1 per farm needed– Hydraulic steering

• $5,000 to convert to hydraulic steering

• All tractors made since 2005 have hydraulic steering

– Guidance package• $23,000• GPS display

RTK in Altus• Western Equipment

– Set up base station to service the region• Sell the signal

– This omits the $10,000 base station set up cost

– $1,500/year (4 yr contract) for each tractor

– $500-600/year maintenance fee• Covers Western

Equipment tower rent, electricity and other costs

ReferencesAyars, J.E., D.A. Bucks, F.R. Lamm, and F.S. Nakayama. 2007. Introduction. p. 1-26. In Lamm, F.R., J.E.

Ayars, and F.S. Nakayama (Eds.) Microirrigation for Crop Production: Design, Operation, and Management. Developments in Agriculture Engineering 13. Elsevier. New York.

Lamm, F.R. and D.H. Rogers. 2002. Minimal system requirements for SDI. Kansas State University.

Manhattan, KS.

Lawless, J.W. 2008. Crop System Specialist. Western Equipment – John Deere4501 E. Main P.O. Box 391Weatherford, OK 73096

(580) 772-5578http://jddealer.deere.com/westernequipment/

McGuire, C.C. 2008. Designs/Consultant. Eco-Drip Subsurface Drip Irrigation.P.O. Box 460

Abernathy, TX 79311(940) 864-4657

http://www.eco-drip.com/index.html

Questions?