p. 1

circles of life conservingresources improvinglife .

[close]

p. 2

contents 3 5 7 10 11 12 13 14 17 18 20 22 overview forms of irrigation water efficiency environmental impact minimizing infrastructure water losses and efficiency management of soil salinity versatility of cropping economic benefits conclusions about valmont appendix front cover sugar cane field in mauritius at right top aerial view of center pivots in colorado usa growing more

[close]

p. 3

food with less water a particularly difficult challenge will be to improve the efficiency of agricultural water use to maintain crop yields and output growth while at the same time allowing reallocation of water from agriculture to rapidly growing urban and industrial uses how this will be managed could determine the world s ability to feed itself mark rosegrant international food policy research institute international irrigation management institute 2

[close]

p. 4

overview growing more food with less water is becoming a critical challenge for agriculture across the world in the 21st century rising populations decreasing water quality and increasing water scarcity are creating burdens on agriculture first a larger population needs more food and fiber second the water quality has decreased due to contamination many times from traditional agricultural methods third agriculture has a diminishing supply of irrigation water to meet these rising demands improving how water is delivered to farms and put to use in fields is essential for meeting the changing needs of global populations improved water management can enhance both food security food safety and human nutrition tremendous inefficiencies in global irrigation methods are numerous and difficult to manage addressing these problems creates many opportunities for progress and economic growth especially in the developing world some environmental problems have been attributed to irrigation overuse of water can indeed cause shortages in river basins or deplete an underground water supply overwatering and lack of proper drainage can load soils with salt damaging the land s productive capacity improperly applied crop chemicals can also leach into groundwater or contaminate surface water above different crops can be grown under a single pivot by dividing the crop circle into segments as in this field in kenya upper left center pivot on barley upper middle valley precision corner upper right valley pivot on jatropha.

[close]

p. 5

irrigated agriculture is becoming more and more important as the nutritional needs of the world grow with our population yet irrigated agriculture faces many formidable challenges however with modern irrigation management advanced agronomic practices and more refined decision-making systems countries facing these challenges can create a more productive and profitable agricultural base societies that capitalize on these opportunities will meet the nutritional needs of their populations and at the same time they can become more competitive in the global marketplace at the most basic level the way that people take care of water must change before they can realize other benefits of enhanced agriculture to grow more food the water farmers use must be managed more carefully mechanized irrigation saves more energy and uses less water and labor than other forms of irrigation it has proven to have the lowest operating costs and longest lifespan of any irrigation equipment available by using irrigation equipment that is more durable and efficient farmers are able to increase their revenue their crop yields and even the land area they farm mechanized irrigation can also help solve other problems such as waterlogged soils salinity and water contamination modernizing irrigation practices then has both economic and environmental benefits mechanized irrigation is an excellent place to begin as countries seek ways to grow more food with less water and human toil at the most basic level the way that people take care of water must change before they can realize other benefits of enhanced agriculture to grow more food the water farmers use must be managed more carefully 4

[close]

p. 6

forms of irrigation development of drip irrigation drip irrigation was first introduced in 1917 by dr lester kellar to irrigate avocados in california in the 1960s this method began to be widely used in israel where the desert conditions and limited water supply created the need for a water-saving agricultural irrigation system drip irrigation allows water to drip out from small emitters to the soil the water travels at low pressure through a network of perforated plastic tubing installed on or below the surface of the soil drip irrigation has been described as the leaking faucet technique since it applies water non-uniformly over a long period of time drip irrigation systems deliver water directly to the soil where it should be most beneficial they also require less water and allow for easier field access than furrow and flood irrigation systems drip systems are particularly suited to the production of vegetable crops that are grown on raised beds including strawberries carrots and tomatoes drip irrigation requires rather intensive management by operators and a sizable initial capital investment drip system operators inspect their fields frequently for problems that affect watering uniformity such as plugs and leaks filters used with drip irrigation to keep particles from clogging the emitters must be flushed regularly drip irrigation systems are relatively expensive with costs as high as $4,000 a hectare for a basic system labor comparison between subsurface drip irrigation and center pivots timing daily maintenance weekly maintenance monthly maintenance annual maintenance sdi center pivot flush filter flush lines chlorinate flush lines grease swivel check oil levels in gearboxes filter check valves confirm emitter performance chlorinate check oil levels in centerdrives

[close]

p. 7

development of sprinkler irrigation in the 1920s sprinkler irrigation was developed sections of small pipeline fitted with vertical tubes topped by sprinklers were moved into newly planted fields then removed prior to harvest in some cases farmers towed these pipelines by tractor from one field to another next came side-roll sprinkler systems the main water line served as the axis for the wheels so it was easier to move however this method still required considerable labor because the system had to be moved every few hours generally these side-roll wheel move sprinklers were used only on shorter crops such as alfalfa potatoes sugar beets and vegetables taller crops could not be grown with those systems introduction of center pivot irrigation by the middle of the 20th century agriculture was ready for a better kind of sprinkler system it was invented in 1952 ­ the selfpropelled center pivot sprinkler over that next decade this new design was gradually accepted as a superior form of irrigation the center pivot concept is simple a long pipeline attached to a central point travels over a field in a circle as it passes over crops sprinklers spaced along the pipeline emit water nourishing the crop below by the mid-60s center pivots irrigated a wide range of crops in the western and central united states valmont founded the center pivot industry and is now the world leader in the manufacturing and development of mechanized irrigation technology valley® brand equipment irrigates more than 5 million hectares in over 90 countries the company s products have been improved through several design generations today the equipment is known for being simple to operate highly reliable long lasting and extremely precise in operation unlike surface irrigation center pivots do not require the extra tillage to prepare a field for furrow or flood irrigation eliminating this tillage saves money and time plus it also allows the farmer to immediately plant another crop in the field ­ a key factor in the success of multiple cropping after one crop is harvested farmers can prepare the field and seed a new crop they can then turn on the center pivot and irrigate the field so that the seeds quickly germinate a benefit the drip systems cannot offer upper left sprinkler packages should be customized to fit terrain and soil conditions rotating sprinkler heads as in this pivot in the pacific northwest united states are well-suited to hilly terrains and heavy soils which have a slow infiltration capacity upper right the low drops and overlapping sprays promote uniformity on this cotton field 6

[close]

p. 8

water efficiency across much of today s world irrigation methods are similar to techniques used as far back as 6,000 years ago some farm families still move water by hand conveying it through earthworks down furrows and across the surface of small plots of land although innovative in ancient times when compared to modern irrigation technologies traditional irrigation uses far more water and human resources than is necessary employing appropriate modern irrigation technology in developing countries is the way for progress increasing agricultural yields improving national economies and empowering farm workers to become more productive with their work time irrigation potential adoption of more efficient irrigation practices ­ along with improvements in water conveyance systems ­ will increase food security modern irrigation practices can improve productivity per unit of water used while changes in conveyance systems will get more water to farms traditional irrigation systems face a number of problems such as low efficiency in water distribution and use unreliable water delivery vandalism of structures poor maintenance and insufficient cost recovery steps taken to improve the productivity of such irrigation projects have generally fallen into three categories · the first concerns timeliness of water delivery predictable distribution ensures that water is available when crops need it most this helps reduce stress-related yields and quality losses reliable supply also encourages farmers to make higher levels of investment in their cropping operations both improvements can increase the value of cropland output · another way project managers try to enhance productivity is by storing unused water and applying it on newly irrigated land · a third kind of improvement involves the reduction of waterlogging and salinity problems these problems decrease yields and degrade productive land eliminating over-application of water can result in production increases due to reduced salinity levels and improved aeration in crop root zones water saved through efficiency can go to other areas that are underserved a fourth trend should be added ­ conversion to mechanized irrigation traditional flood irrigation methods waste a great deal of water besides low water efficiency over-watering also leads to low crop yields especially as salts are brought up into the crop root zone the precise water application afforded by mechanical move irrigation uses half as much water as flood and allows control of leaching of salts when water is applied uniformly across a field and in the exact amounts needed by the crop the crop yields can be dramatically higher and the soil does not become water logged or overly salinized fresh water conservation a recent world bank report stated that unless current trends in water use are reversed the world s water crisis will worsen the world needs a healthy and growing food-producing sector irrigation will provide enormous value in terms of food security with growing concerns over the world s fresh water supply mechanical move machines provide a sensible alternative to inefficient forms of water application such as surface flood irrigation water use in irrigation could be lowered dramatically with no loss in food production mechanical move machines greatly reduce excess water use by applying precise amounts of water to crops at the right times and in the right quantities modern mechanized equipment is extremely water efficient specialists define irrigation system efficiency as the ratio between the water applied by irrigation system and the water used by the plants on that field traditionally surface irrigation methods achieve efficiencies ranging from 40 to as high as 70 if field runoff is collected in holding ponds for reuse in much of asia surface irrigation efficiency typically is 25 to 40 losses of water in the distribution system and in farm fields account for this inefficiency the irrigation efficiencies achieved by center pivot and linear move machines range from 75 to 95 depending on sprinkler package design irrigation scheduling valley pivot on sugarbeets.

[close]

p. 9

initial investment cost comparison 4500 4000 cost per hectare in us dollars 3500 3000 2500 2000 1500 1000 500 0 surface pivot drip $4075 $2465 $1350 irrigation technology based on a 50 hectare center pivot data from dumler troy j o brien daniel m and rogers danny h irrigation capital requirements and energy costs kansas state university october 2007 low clearance low pressure sprinkers used for precise water application crop input application center pivots and linear move irrigation equipment apply water precisely as do well-managed drip irrigation systems precise water application ensures that crops get the right amount of water at exactly the right time rather than too much or not enough water the precise water application capabilities of mechanical move irrigation equipment can also be used to apply other crop inputs for example fertilizer can be mixed with irrigation water and applied during the growing season pivots and linears can thus deliver nutrients to crops as well as water when the growing plant needs them most applying nutrients during the growing season reduces the need to apply heavy doses of fertilizer before the crop is planted it is in the early part of the season ­ when soils lay bare to wind and water ­ that the risk of erosion is greatest when the soil washes away so do fertilizer and crop inputs this is one way in which water quality can be compromised fertilizing plants later in the season when a crop canopy protects the soil helps keep fertilizer where it belongs other chemicals can also be applied through center pivot or linear move irrigation equipment farmers can thus treat insect outbreaks or control weeds as they apply irrigation water once again applying chemicals only when they are needed helps keep them in fields and out of aquifers streams rivers and lakes hay grown under a pivot and other agronomic practices practices such as lepa low energy precision application can optimize the water efficiency of mechanical move irrigation technology exact quantities of water are delivered to crops and with proper design runoff and evaporation losses are nearly eliminated mechanical move irrigation technology such as pivots and linears ranks side by side with drip irrigation as the most water-efficient forms of irrigation available today another problem with surface irrigation is the lack of uniform application water must be overapplied on one side of a field so it can flow to all parts of a field this leads to waterlogging lower yield and quality and soil degradation uneven water distribution in surface irrigation is a key cause of reduced crop quality and yields a center pivot or linear machine can apply water at 88 to 95 uniformity compared to 40 to 70 uniformity with surface irrigation complementary agronomic advances delivering water to crops at the optimal time and efficiently applying it in exactly the right amounts are only part of the answer as irrigation becomes more reliable farmers become less susceptible to risk because they know the water will be there when they need it optimizing water use should be accompanied by the adoption of complementary agricultural inputs unless farmers use improved seed fertilizers pesticides and new cultural practices in addition to modern irrigation they will not maximize the potential benefits which modern technology offers 8

[close]

p. 10

water availability and scarcity in total there is enough water to support a world population many times larger than the present one unfortunately water is unevenly distributed across the surface of the earth many regions lack access to sufficient affordable fresh water competition among fresh water users in the agricultural domestic and industrial sectors is increasing as their water demands grow agriculture accounts for approximately 70 of human water usage today however the agricultural share of the water supply will decline as the water demand of households and industry increases the united nations environment programme unep defines as water stress those countries where local water supplies average less than 1,700 m3 per person per year and water scarce as those less than 1,000 m3 in 2007 about 450 million people lived in 29 countries where the internal renewable water supplies were less than 1,700 m3 per person per year by 2025 one in three people will live in water stressed areas and 1.8 billion people will live in areas with absolute water scarcity fao in general africa and asia are already showing signs of a worsening shortage in freshwater availability and water quality is also declining globally countries and regions where water resources are under particularly strong pressure are especially good candidates for increased food imports and irrigation modernization.

[close]

p. 11

environmental impact the world has approximately 280 million hectares of irrigated land if just 1 of this land was converted from traditional irrigation methods to precision methods more than 7 million cubic meters of water could be conserved annually this is equal to enough water for nearly 103,000 households per year worldwide these savings would make a major contribution in solving water shortages around the globe precise uniform application not only conserves water it also increases crop yields quality and revenue modern irrigation methods can help the world grow more food with less water water quality one of the major issues facing surface irrigation is water contamination from chemicals fertilizers pesticides and other pollutants can leach into groundwater and pollute streams lakes and rivers when chemical-laden irrigation water is over-applied and flows from farm fields into other waters mechanized irrigation enhances environmental safety by applying only as much water as the soil can absorb runoff is eliminated or reduced significantly using mechanized irrigation to apply crop inputs permits more precise control of irrigation rates and timing which increases the effectiveness of crop chemicals and fertilizer potential treatment needs may be reduced also more effective irrigation improves plant health lush crops can shade weeds and better withstand insect pressure making some treatments unnecessary in similar fashion the equipment can be used to apply growth regulators and harvest enhancement products on crops such as cotton research has also shown that center pivot irrigation equipment can draw on groundwater that is contaminated by fertilizers and filter that water through the crop root zone cleaner water is the result another benefit to using mechanized irrigation is that there is no need for tillage to prepare cropland to convey water in furrows more protective crop residue cover can be left on fields since most water pollution is caused by soil sediment increased crop residue helps keep soil in place to reduce erosion when cropland is tilled chemical contaminants are often carried into waterways on soil particles controlling soil erosion thus also contributes to reduced chemical contamination in some areas wastewater treatment is a major challenge center pivots and linear move equipment can apply partially treated wastewater onto cropland again crop roots filter the nutrients and clean the water this results in major savings by avoiding added costs for additional capacity in sewage systems reduced runoff from irrigation can also help protect the productive capacity of soils water soaks into the soil rather than running off the field preventing soil erosion the center pivot compliments the modern trend towards minimum tillage farming practices with less tillage needed under center pivots less soil will blow away in the wind mechanized irrigation helps protect the soils that are so critical to farmland productivity there are many ways that mechanized irrigation can contribute to enhanced environmental quality ­ using less water reducing runoff and potential chemical contamination and solving soil erosion problems opposite page upper left canola irrigated under a pivot in australia bottom left lepa irrigation with drag socks and low drops ensure efficient application of water bottom right map from fao nations unies world resources institute wri current page upper right the valley 3-wheel drive offers a traction and flotation solution 10

[close]

p. 12

minimizing infrastructure the traditional view of the infrastructure required for irrigation has slowed or stopped development in many cases due to the scope in size and/or energy requirements to deliver sufficient water to meet a plant s water requirement surface irrigation requires twice as much water as modern irrigation technology due to field losses storage reservoirs intake structures canals turn outs and other components need to be sized accordingly to handle this large volume if traditional sprinkler irrigation is being used 50 more water is delivered than required by the plants however the delivery pressure in the field may be as high three bar or more this requires large high pressure pumping stations and a high pressure water delivery structure also the annual operator costs are much higher due to the additional power required precision irrigation such as drip or mechanical move requires a delivered volume of only 10 to 15 more water than required by the plant at a pressure of 1.0 to 1.5 bars drip has a higher infrastructure requirement due to the filtration needed to protect the many water outlets in the lines and tubes from plugging mechanical move has a low energy requirement due to requirements for 1.0 to 1.5 bar in the field and does not have a high filtration requirement since the water application of mechanical move irrigation does not use small orifices to control flow typically filters for mechanical move irrigation range from 2.4mm to 4.0mm if necessary at all in contrast the typical filter size for drip irrigation is .08 to .10mm in addition to minimizing the infrastructure requirements for new development mechanical move irrigation also can utilize existing infrastructure that may have deteriorated over time this reduces the need for upgrades or improvements due to the low energy requirements and the low volume needed to be delivered to the field above a 90 95 water application uniformity can be achieved with proper sprinkler package design many variables must be taken into account including the water needs of the crop soil intake capacity the available water pressure wind heat and soil salinity.

[close]

p. 13

water losses and efficiency water losses irrigation efficiency is determined by the ratio between the water used by plants and the water applied to the field this illustration shows where water losses occur it should be the irrigator s attempt to maximize the water retained and transpired by the crops in his field relative to the water supplied at the source unfortunately due to inefficient practices and obsolete technologies the water loss can be greater than what is utilized by the plant by using efficient equipment and practices an irrigator can maximize the water that actually benefits the plant and reduce the losses which can not be utilized to avoid delivery run-off evaporation and deep percolation losses the following options are suggested water delivery losses · sealing of supply canal · pressurized pipe delivery run-off losses · balance soil intake to water application · uniform application · minimum tillage below root zone percolation losses · precise scheduling of applications · monitor moisure of the soil below the surface · uniform application evaporation transpiration losses in delivery of water to the field run-off of excessive water water percolation below the root zone average irrigation water losses farm distribution losses 15 irrigation system losses 15 field application losses 25 evaporation losses · sprinklers close to or within crop canopy · reduce surface wetting intervals · avoid high wind irrigation applications · utilize soil moisture holding capacities for heavier applications water used by the crop 45 the overwhelming majority of the world s irrigators are handicapped by obsolete equipment and technology which limits their ability to employ these practices and minimize the amount of water wasted the only technologies which enable the irrigator to utilize these practices are mechanical move center pivots and linears and micro drip micro-spray and sub-surface equipment unfortunately less than 5 of the world s irrigators currently utilize these two technologies the vast majority of irrigators still use technology created thousands of years ago is it any wonder that we are facing a crisis in the cost availability and quality of water allocated to agriculture data from un fao the vast majority of irrigators still use technology created thousands of years ago is it any wonder that we are facing a crisis in the cost availability and quality of water allocated to agriculture 12

[close]

p. 14

management of soil salinity salinity is a major challenge for irrigated agriculture it can damage the land reduce yields and interfere in the growth of food production one of the contributors to salinity is waterlogging often found in surface flood irrigated fields when soils become waterlogged due to over irrigation and/or lack of proper drainage salts accumulate in the root zone of plants and on the surface of the fields these salts impede root system development and nutrient uptake as a result crop yields can be reduced by as much as 30 or in a worst case scenario it may remove sections or even the entire field from productivity in recent decades millions of hectares in farms throughout the world have suffered from saline soils irrigation practices such as flood and drip irrigation can cause the gradual build-up of salts at the root zone of crops eventually damaging or killing the roots with the use of mechanized irrigation equipment salinity buildup in the root zone can be prevented or often even reversed with the ability to leach the salts beneath the crop root zone by controlling the timing and uniform application depth of the water protecting soil resources protecting current irrigation land from further salinization will help reduce productivity losses reclaiming lands already affected by salinity also should be pursued to protect the irrigation land base modern precise mechanical move irrigation technology can help in both situations both leading modern irrigation technologies ­ drip and mechanical move equipment ­ apply less water than surface irrigation which eases problems associated with waterlogged soils and poor drainage however with drip there is the potential to have salt build up in those regions where the wetted soil meets the dry soil since there is not a uniform application of water as is typical with precision mechanical move irrigation extremely careful management and frequent soil and water analyses are the only ways to monitor and manage saline build-up only mechanical move irrigation can apply water to flush salts below the root zone while avoiding waterlogging the soil above top salt build-up in surface irrigated onions most irrigation techniques cause salts to build up in soils center pivots can both remediate and prevent soil salinization above bottom dark areas indicate where soil salinization is a major problem.

[close]

p. 15

versatility of cropping versatility and crop production center pivots and linears are used in widely varying climates and topography the equipment waters a wide range of soil types from extremely sandy to fine-textured clay soils it can draw on many water sources using surface water aquifer ground water saline water and wastewater above top sugar cane fields above the pivot irrigating this citrus orchard is fitted with `below the canopy sprinklers which minimize evaporation and concentrate their spray directly over the crop root zone when first introduced the equipment was often installed on hilly land in dry regions in these areas water was accessible but surface irrigation was not possible as this low-cost land was developed it produced top yields within one to two years today center pivots and linears in many cases are replacing surface irrigation on flat lands these farms are being converted to mechanized irrigation for many reasons mechanized irrigation uses 25 to 50 less water than surface irrigation and reduces labor up to 75 these factors allow farmers to raise crops on more hectares using roughly the same amount of water and less labor mechanized irrigation also allows producers to practice superior farm management the technology is also used in rainfed farming regions even where annual precipitation often reaches 1,200 mm to 1,500 mm the timing of rain may not match crop needs if precipitation is highly variable pivots and linears protect yields during dry years once mechanized move irrigation has proven itself in a region its importance grows rapidly moisture variability during the growing season is a farmer s biggest risk with the decreased risk that mechanized irrigation provides farmers can afford to invest more in their farming operation unless progress with agricultural yields remains very strong the next century will experience sheer human misery that on a numerical scale will exceed the worst of everything that has come before dr norman borlaug nobel prize laureate importance of irrigation 14

[close]