Sub-surface Drip Irrigation and Modern Agriculture Elliott W. Rounds April 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 $ /ac – USDA programs available Most are 50% cost share

80” tape spacing in cotton Place 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 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 – $ /year maintenance fee Covers Western Equipment tower rent, electricity and other costs

References Ayars, J.E., D.A. Bucks, F.R. Lamm, and F.S. Nakayama Introduction. p 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 Minimal system requirements for SDI. Kansas State University. Manhattan, KS. Lawless, J.W Crop System Specialist. Western Equipment – John Deere 4501 E. Main P.O. Box 391 Weatherford, OK (580) McGuire, C.C Designs/Consultant. Eco-Drip Subsurface Drip Irrigation. P.O. Box 460 Abernathy, TX (940)

Questions?