Alternative (more efficient) Irrigation Systems David A. Bainbridge Author: 2007. A Guide to Desert and Dryland Restoration. Island Press. Retired, former Associate Professor, Alliant International University, San Diego, California Water shortage! • The problem of water shortage continues to grow - both locally and globally • At the same time the need for restoration of dry lands and increasing food production from deserts and dry lands are both rising • This led to my twenty five year adventure with alternative irrigation systems Desertification Desertification: now affects 1 billion people Northern Mexico The First Step • This is not a “new” problem so I started with an extensive literature search • I also interviewed scientists and farmers who visited the Dry Lands Research Institute (at UC Riverside) • Several interesting candidates emerged, and have proved useful! Buried Clay Pot Irrigation • One of the most studied, and very effective systems uses a buried clay pot full of water to irrigate plants • The capillary flow of water is regulated by demand - so little water is wasted • Highly recommended! For restoration, gardens, landscaping, farming Simple and Effective • Clay pots worked well even in the lowest, hottest desert in California • Excellent for seedlings or for starting seeds or cuttings Getting Started • Regular red clay pots work well • Seal the bottom hole with a cork or sealant • Use a lid with a small hole drilled in it to capture rainwater Place the pot • Set the pot in the soil so the rim is above ground • You don’t want the dirt and leaves to wash in • Firm the soil around the pot -- and plant A Long Tradition • The agricultural text Fan Sheng-chih Shu, describes the use of buried clay pot irrigation in China more than 2,000 years ago • Excerpts from this book provided my inspiration--writing does speak across time • I later found work and use of clay pots in Iran, Pakistan, Mexico and other countries Fewer Weeds • Another great advantage of buried clay pots (and other deep watering systems) is reduced weed growth • In one study weeds were cut 87% • This means less work - and less wasted water! • The second biggest problem for small farmers after water shortage is time shortage Buried clay pots • Buried clay pots have also proved to be very effective when saline water must be used - or when salt is a problem in the soil • The steady moisture reduces salt buildup in the root zone and damage Starting Cuttings • Double clay pots are ideal for starting cuttings • The inner pot is sealed and filled with water • The moisture is maintained in the soil at an ideal level • BCP are good for starting cuttings in the field as well Deep Pipe Irrigation • This method of irrigation was suggested by a traditional system from India - where water was placed in the hollow stem of a dead plant to water deeper in the soil • Subsequent research found one study and one report from India • This has been our best system for restoration work -- cheap, durable and very effective Deep pipe installation • The pipe may be about 14-16” long, 2” diameter, set vertically • Small holes are drilled on the plant side below soil level • A screen lid is glued on to protect wildlife Deep pipe drip • Where a drip system can be set up it can also be used in a deep pipe • Smaller pipes can be used with the emitter inserted in the pipe No waste • Little water evaporates because the water is placed in the deep soil • Little time is wasted because it is fast and easy to fill the pipe • It works very well on slopes • It develops large root systems Excellent Results • Survival is excellent with very little water • Mesquite trees were started with a total of only 5 gallons of water in the first year - not five gallons a week or two gallons an hour Wick Irrigation • Wick systems were also described in reports from India • Wicks were traditionally combined with clay pots to water orchard trees • After trying several types of wicks I think this may be the next great thing! Wick options • Wicks can be used in a capillary form, where water is wicked from a reservoir to the plant through a raised section by capillary forces (as little as 20 ml day) • Or in a gravity feed form, with the reservoir above the wick (a hose clamp can be used to adjust the flow rate) Wick options • Wick with clay pot • With a riser tube in bottom hole • Capillary wick from buried bottle in plastic tube More wick options • Half inch diameter gravity wick with a larger reservoir • Installed with treeshelter and wire cage for jack rabbit protection • Seedlings topped treeshelter at 3 weeks! Wick Material • The best material has been old, used 812 mm solid braid nylon rope (5/16”-1/2”) • Fresh nylon rope can be used if it is washed with detergent to remove oils but it is not as good as old rope • Fabric ca also be used • Cotton was used in India, but tended to mold in my early tests Porous Hose • This system uses a vertically placed leaky or porous hose section • It performs a bit like a clay pot--only it is cheaper and smaller • These hoses are made of recycled rubber and hold up well • It has to be high flow rate hose to work at low pressure head Porous hose • This can be fed by a bottle • Or attached to a drip type line • Both have worked reasonably well • A fast rate hose is needed to work at low pressure Tree shelter • Watering into a tree shelter is also effective • This can be done by hand or using a drip type system Perforated Pipe • Sub-irrigation can also be done with slotted drain pipe • The pipe is laid deep in the soil and filled with water using a water truck • Best for lines of plants - good for landscaping Porous Capsules • A modern adaptation of buried clay pot irrigation was developed in Brazil • The clay is formed into a capsule that can be placed on a water line • These worked well for me -- but were more costly to make Types • PC made by gluing two red clay pots together • Clay pots made by a staffer using a beer bottle mold Porous capsules • These are easy to plumb in a system • Or they can be gravity fed from a bottle or tank • These are very efficient indeed • A range of smaller porous irrigation systems are sold for container plants Microcatchments • A microcatchment is a specially contoured area with slopes and berms designed to increase rain runoff and concentrate it in small dams or depressions • Rain falling on the catchment area drains into a planting basin where it infiltrates and is effectively "stored" in the soil profile • Used for millennia - very effective if it rains! A Microcatchment • Microcatchments can be shaped to look more natural, but do entail disturbing the soil surface • More appropriate in agriculture - but has worked well on restoration projects Problems with drip • Drip irrigation has been very effective in agriculture and is often the best choice, but we can do better for the hundreds of millions of farmers who cannot afford drip • Water for drip must be filtered and pressurized and maintenance is critical • It is also not as efficient as these alternatives - some may be 2-4 times more water efficient than surface drip Drip problems • Drip is not well suited for remote sites - due to animal damage • Even when open water is nearby animals will chew on drip tubing • Insect, root and salt clogging and other problems also occur regularly The best system? • It depends • All have been very good • Deep pipes have been most commonly used • Perforated pipe is now used in some situations (linear plantings Mojave) • My current research is focusing on wicks - low cost, durable Container type • The container type and planting system make a difference in irrigation choice • Tall pot, half high, deep pot, plant band or supercell? • Watering interval • Goals for survival and growth How efficient? • My goal has been to irrigate plants with minimal water use -- perhaps a quart a month for species like mesquite • This has been possible if they are also planted with a tree shelter to reduce temperatures and exposure to the wind • They don’t grow much - but they survive until it rains Restoration in remote places • My goal has been to reduce water use during establishment to a low enough level to be done by hand carrying water • Or using a mule, many miles from the water source It is possible Planted 1995, photo 2008 More information • A wide range of papers and web sites • Try ecocomposite.org • Sakia.org • And for more information on desert Restoration www.desertrestore.org www.desertrestore.org June 2007 You Can Help • Try these systems -- figure out how to make them better, cheaper and more efficient • Find out what works and what doesn’t and let me know sustainabilityleader@gmail.com • Send money to support research • Buy my book on desert and dryland restoration and send it to a library or university in Africa, Mexico, Asia Thanks • To friends, students (AIU, SDSU, UCR, WCIU), staff, funders, vendors and family who have helped along the way • To the traditional farmers who figured most of this out -- and shared information and ideas freely • Special thanks to Steve Mitchell, Wes Jarrell, Ross Virginia, Mike Allen and John Rieger who made this possible • And to the many scientists and extension specialists who have provided insight and descriptions of traditional irrigation systems