USAGE OF DRIP IRRIGATION SYSTEM IN CROP PRODUCTION
The aim of this research is to bring people’s attention to the importance of using the drip irrigation system in crop production to increase crop yield and quality, and decrease water consumption because of the decreasing water sources and rising effects of global warming. If government gives incentive for setting up the drip irrigation system and farmers use the drip irrigation system in crop production, crop yielding will increase, and consumption of water will reduced significantly. The indirect method entailed consulting numerous resources such as books (e-books), documents, articles, and websites that contained data, information, and analysis results that explain the usage of drip irrigation system. The development section of the report demonstrates that the drip irrigation system is the most effective methods to use in crop production and to get significant results from the system. This report concludes that because of the higher initial cost of establishing the drip irrigation system, government subsidy is important to increase the number of farmers who use the drip irrigation system.
Today’s one of the most important issue is innovation in all sectors. Especially innovation in agriculture and irrigation became mandatory because of the growing economic and physical scarcity of water, compounded by rising cost of developing new and further sources to meet increasing demands for water. By the increasing of water demand in agriculture, new and modern irrigation systems have emerged in last 25 years. For example, sprinkler and drip irrigation systems. Drip irrigation system (also called trickle or micro irrigation system) is an irrigation method that minimizes the use of water, fertilizer, and nutrients by permitting water to drip slowly, regularly and frequently to the roots of plants. By the drip irrigation system, water is delivered either into the soil surface near the base of plants or directly into the root zone of plants through a network of tubing and emitters. Drip irrigation is a new system developed within the last 25 years for the countries that have water scarcity. Development of modern drip irrigation system began in Afghanistan in 1866. In 1913, Colorado State University achieved applying water to the root zone of the plants without raising the water level.1 However, study of Colorado State University about the drip irrigation system was not enough to provide benefit to the users of drip irrigation system. Modern day trickle irrigation system was done in Israel in 1963 and in Usa in 1964. With these studies, instead of releasing water through a water hose, water was released through larger and longer passageways by using velocity to slow water inside a plastic emitter. Today, many studies on design, operation and management principles of drip irrigation system have been under taken by the Jobling (1973); Merriam and Keller (1978); Nakayama and Bucks (1986) and Kanber (1999).2
http://en.wikipedia.org/wiki/Drip_irrigation Tekinel Osman, Kanber Rıza and Diker Kenan, 2000, The potential use of drip irrigation systems for sustainable agriculture under saline water and soil conditions, page 4
Drip irrigation was first used about 45 years ago but its wide scale adoption commenced in 1970s when it was used on 56,000 ha. According to the key outcomes and recommendations of 7th international micro irrigation congress in 2006, currently, 6 million hectares (Mha) are under drip irrigation system world over. The highest coverage is in Americas (1.9 Mha) followed by Europe and Asia (1.8 Mha each), Africa (0.4 Mha), and Oceania (0.2 Mha). The top ten countries in micro irrigated areas are Usa, Spain, India, China, Italy, Brazil, Russia, Mexico, Saudi Arabia and Australia. These ten countries share about 75% of the total micro irrigated area of the world.3 Main principle of drip irrigation system is that giving water to the roots of plants frequently by the help of the pressured pipes and emitters with maintaining favorable soil moisture condition and prevent moisture stress in the plant. In an effective irrigation system, water is distributed as close as possible to the plant’s roots. When compared with another type of irrigation systems, drip irrigation accomplishes this process more efficiently. Most important property of drip irrigation system is that taking advantage of the minimum water in most efficient level. With drip irrigation system, we can control where the water is applied, which increases water efficiency and helps minimize weed growth. Because, in drip irrigation system only roots of plants are dampened, other surfaces are not dampened. The ICID (International Commission on Irrigation and Drainage) surveys indicated that the main reasons for choosing drip irrigation system were as follows: Water and labor are expensive Water supply is limited Water supply is saline The use of other irrigation method is difficult Landscaping or greenhouse irrigation is required Chemigation is possible3
Drip irrigation system are typically about 90% efficient, as compared to sprinkler system which are about 75% efficient. Water savings may reach 50% and crop yields can be increased up to 40 %.4 Today, because of the decreasing water sources and rising water demand we have to consider how we can use water more efficiently. Therefore, the importance of utilizing drip irrigation system is increasing considerably in crop production. Accordingly, in the study to be presented here, firstly, we summarized the components of trickle irrigation system. After, types of drip irrigation system will be shown. Furthermore, the advantages and disadvantages
Freddie R. Lamm, James E. Ayars, Francis S. Nakayama, (2007), Micro irrigation for Crop Production: Design, Operation, and Management, Elsevier press, page 5 4 Smith, Amy. Technology brief: International development enterpriser’s irrigation system, low cost drip irrigation.(web.mit.edu/d-lab/resources/nciia_files/tb-di.pdf)
of micro irrigation system shall be examined. We also sought to study the economic consequences of using drip irrigation system. Finally, usage of drip irrigation system in Turkey will be explained.
2) DRIP IRRIGATION SYSTEM 2.1) COMPONENTS OF DRIP IRRIGATION SYSTEM
A drip irrigation system has five major components: Delivery system Filters Pressure regulators Valves or gauges Chemical injectors
2.1.1) DELIVERY SYSTEM 188.8.131.52) Mainline distribution to field Water is delivered by underground pvc pipe or above ground aluminum pipe from its source (pump, filtration system, etc.) to the sub-mainline. 184.108.40.206) Sub-mainline Using vinyl (synthetic plastic material made from polymerized resin) “lay flat” hose, as a sub-mainline is common method. This hose must be durable and long lasting. The lay flat hose, connectors, and feeder tubes are retrieved after each growing season and stored until the following year. It is not easy to roll up at the end of the season since polyethylene pipe become more rigid.5 220.127.116.11) Connectors There are two basic methods to connect the drip tape to the sub-main. First method uses small plastic tubes called by feeder tubes to connect the sub-mainline to each drip tape. Feeder tubes can be inserted directly into the vinyl hose. In the second method, drip line is connected to the sub-main by the plastic connectors or couplings.6
Penn State University: Drip irrigation for vegetable production. (http://agalternatives.aers.psu.edu/Publications/DripIrrigation.pdf) 6 Penn State University: Drip irrigation for vegetable production. (http://agalternatives.aers.psu.edu/Publications/DripIrrigation.pdf)
18.104.22.168) Drip lines Two basic types of drip lines are used in drip irrigation system. Firstly, with turbulent flow drip tape most commonly used type of drip line, which is thin walled and has emitters formed into its seam during manufacturing. Drip tapes are operated at pressures ranging from 6 to 15 ppsi (unit of pressure). Drip tubes with internally attached emitters are an alternative to turbulent flow drip tapes. This type of drip lines tend to be more expensive, but often have better water distribution uniformity and better clogging resistance than turbulent flow drip tapes. These products are common in enduring applications. 6 2.1.2) FILTERS Filters are essential parts for the operation of a drip irrigation system. Many devices and management techniques are available for cleaning irrigation water. Depending on the water source, settling ponds, self-cleaning suction devices, sand separators, media filters, screen filters, and disk filters are used with drip irrigation system. Media, screen and disk filters are characterized by the size of holes the water passes through in the filter element. Media filters are the most common filters used in drip irrigation system for the commercial crop production which ranging from 14 to 48 inches in diameter. Media filters are expensive, heavy, and large but they can clean poor quality water at high flow rates. 7 Screen filters are used widely in drip irrigation system, which can remove debris efficiently as a media filter. Screen filters are open or pressure type of filter. An open screen filter removes trash and other organic material from the water before it passes through the media filter. A pressure screen filter is used primarily to remove inorganic contaminants such as undissolved fertilizer salts or sand that may have escaped the sand filters. 8 Disk filters are relatively new devices that have characteristics of both media and screen filters. The screening elements of a disk filters consist of stacks of thin, doughnut shaped, grooved disks. 7 2.1.3) PRESSURE REGULATORS In the drip irrigation system, water pressure is decreased by the pressure regulators. Variations in pressure owing to ascent change can be handled by using pressure regulators. Two types of pressure regulators are used in drip irrigation system. First of all, adjustable regulators are used where the output pressure level is set by the user. Secondly, fixed regulators are another type of pressure regulators that have a fixed output pressure. In addition, fixed regulators are less expensive than adjustable regulators. 9
Penn State University: Drip irrigation for vegetable production. (http://agalternatives.aers.psu.edu/Publications/DripIrrigation.pdf) 8 Merle H. Jensen and Alan J. Malter, (1995), World bank technical paper number 253, Protected agriculture: A global review, world bank publications, page 72 9 Oklahoma State University: Drip (trickle) irrigation systems. (http://osuextra.okstate.edu/pdfs/F-1511web.pdf)
2.1.4) VALVES OR GAUGES Watering several fields or sections of fields from one water source can be achieved by using automatic or manually operated valves. When using a well or municipal water source or injecting fertilizers or chemicals into the system, a backflow/anti-siphon valve is necessary. Hand operated valve types automate system using a time clock, water need sensor or computer controller. 7 2.1.5) CHEMICAL INJECTORS There are three types of chemicals, which are injected into trickle irrigation system. These are fertilizers, pesticides and anti clogging agents. Fertilizers are the most common type which responsible for the yield increases resulting from drip irrigation. Furthermore, systemic pesticides are frequently injected into a micro irrigation system to control insects and protect plants from different diseases. Chemical that prevent or fix clogging problems are also injected into trickle irrigation system. In order to kill algae, chlorine is used and acids are used to adjust water pH and dissolve definite precipitate clogs. 10
2.2) TYPES OF DRIP IRRIGATION SYSTEM
Drip irrigation system can be classified into two categories as follows: Surface drip irrigation system Subsurface drip irrigation system
2.2.1) SURFACE DRIP IRRIGATION SYSTEM Surface drip irrigation is the dominant type of drip irrigation system. This type of drip irrigation system uses emitters and lateral lines positioned horizontally on the soil surface or attached aboveground on a trellis or tree. In this type of drip irrigation system, monitoring and controlling of drippers’ performance is very easy and efficient. Furthermore, unfortunately the laterals are tending to be mechanical damage and degradation by the solar radiation and farming activity. 10 2.2.2) SUBSURFACE DRIP IRRIGATION SYSTEM Subsurface drip irrigation system (SDI) is another type of drip irrigation system, which refers to the practice of installing drip below the ground surface. Since the early eighties, subsurface drip irrigation technology gained momentum. In subsurface drip irrigation system, low flow rate of water are delivered directly to the roots of the plants by the drip laterals that are buried 10-50 cm below the soil surface. A welldesigned and maintained system may last more than 20 years.
Sen Moshe, Guidelines for planning and design of micro irrigation in arid and semi-arid regions, ICID publication, page 24
2.3) ADVANTAGES AND DISADVANTAGES OF DRIP IRRIGATION SYSTEM
2.3.1) ADVANTAGES OF DRIP IRRIGATION SYSTEM There are several advantages of drip irrigation system. The most important benefits are highlighted in the following sections. 22.214.171.124) Increased water efficiency and saving Water application efficiency is an irrigation concept that is very important both in system selection and design and in irrigation management. Significant improvements in yield have been documented with the usage of drip irrigation system without the significant increases in the consumed water.12 The uniform application of water in drip irrigation system can achieve high water efficiency. By applying water only where it is needed, there is less surplus and evaporation from leaves and soil. In the drip irrigation system, water is used 30 to 50 percent less than conventional watering methods. According to recent study at the University of Rhode Island, drip irrigation is more than 90 percent efficient at allowing plants to use the water applied.12 126.96.36.199) Improved crop yields and quality With the drip irrigation system crop quality and yield is improved because of the slow, regular, and uniform application of water and nutrients. Explanation for the improvement in plant growth, yield and crop quality are related to improved water distribution along the row which can reduce plant stress caused by variations in texture and water holding capacity in heterogeneous soils.12 Drip irrigation system can be automated to allow frequent applications. Drip irrigation also can be used to frequently inject fertilizers and other chemicals such as acids, chlorine, and pesticides with the irrigation water. Drip irrigation system is managed to apply small amounts of water and other inputs daily or several times a day. Small and frequent applications can be adjusted to match the water and nutrient needs of the crop.13 188.8.131.52) Use of saline water Use of saline water is another advantage of drip irrigation system. Water with relatively high salt content can be used by the drip irrigation system. Minimizing the salinity hazard to plants irrigated by drip irrigation can be attributed to: 1- Keeping salts in the soil water more diluted because the high frequency irrigations maintain a stable soil water condition. 2- Eliminating leaf damage caused by foliar salt application. 3- Moving salts beyond the active plant root zone. Furthermore, inappropriate placement of the system in relation to the crop could increase the salinity hazard by moving the salt into the root zone.12
184.108.40.206) Improved fertilizer and other chemical application Drip irrigation system allows high level of controlling chemical applications. Frequent application of plant nutrients with the irrigation water is feasible and appears to be beneficial for many crop production situations. The plants can be supplied with the exact amount of fertilizers required at a given time. Since fertilizers are applied directly to the root zone of a plant, a reduction in the total amount of fertilizer is possible. There is also an advantage to the frequent application of fertilizers. In the case of rain, only a small portion of applied fertilizer will be washed out and it can be easily replaced through the irrigation system. This application method is more economical, provides better distribution of nutrients throughout the season and decreases ground water pollution due to the high concentration of chemicals.14 Moreover, other chemicals, such as herbicides, insecticides, fungicides, growth regulators and carbon dioxide can be efficiently applied through drip irrigation system to improve crop production. 220.127.116.11) Other advantages of drip irrigation system Drip irrigation system can be used effectively on extremely steep ground. No other irrigation method can be used on extreme terrain. Drip irrigation system requires minimal land grading. Land grading is necessary to prevent surface drainage problems that may occur with rain and to accommodate any special tillage (agricultural preparation of the soil by ploughing it) equipment used. Lower operating pressures. That is, reduced energy costs for pumping. In drip irrigation system, disease pressure may be less because plant foliage remains dry. Labor and operating costs are usually reduced. Growth of weeds is reduced due to partial wetting of soil. Drip irrigation system is convenient for cultural practices. The field is always accessible for spraying, weeding, and harvesting. In drip irrigation system, there is less soil erosion. Soil type plays less important role in frequency of irrigation.15
2.3.2) DISADVANTAGES OF DRIP IRRIGATION Despite the possible advantages of drip irrigation system, some disadvantages have been encountered with the economics and mechanics of applying water with drip irrigation system for some soils, water qualities, and environmental conditions. The disadvantages of drip irrigation are highlighted in the following sections.
18.104.22.168) Initial cost One of the main disadvantages of drip irrigation system is its high initial investment cost. Drip irrigation system is expensive compared with the other irrigation systems. Cost per acre varies widely, depending on field size and shape, location of the water source and level of automation.13 Also, filters, chemical injectors and possible automation components add extra costs to the drip irrigation system. Actual costs will vary considerably depending on the selection of a particular drip system, required filtration equipment, water quality, water treatment and selection of automation equipment.14 22.214.171.124) Extensive maintenance requirements Complete or partial clogging of emitters represents a serious problem with drip irrigation system. Clogging will adversely affect water and fertilizer application uniformity, increase maintenance costs and cause crop damage and decreases yield if the clogging is not detected early and corrected. Other maintenance problems are pipeline and component damage such as leaks or flow restrictions that can be caused by rodent or other animals, personnel, poor installation actions or machinery.12 126.96.36.199) Clogging problem One of the biggest problems encountered under drip irrigation system is clogging of the emitters. The small openings can be easily clogged by soil particles, organic matter, bacterial slime, algae or chemical precipitates. Therefore, the drip irrigation system requires very good filtration with a good quality water supply.14 188.8.131.52) Soil salinity An important concern with drip irrigation system is that soil salinity above the drip lines can increase with time. Soil salinity problem may take a relatively long time to develop and soil salinity problem is not likely to occur in areas where receive enough precipitation at any given time to move the salts down in the soil. The quality of the water used for irrigation is another important factor when considering the danger of developing soil salinity problems.13 184.108.40.206) Other disadvantages of drip irrigation system Management requirements are higher. Rodent, insect, and human labor may cause damage to components and create potential sources of leaks. Drip irrigation is not suitable for closely planted crops such as alfalfa or cereal grains. Germination problems. In lighter soils, drip irrigation system may be unable to wet the soil surface for germination. Requires careful consideration of the installation depth.15
2.4) ECONOMY AND DRIP IRRIGATION
Water is the most abundant resource on earth but it is limited for human consumption. Because 97% of all water is saltwater, 2% is held by in snow, and icebergs, and only 1% is -8-
freshwater (useable for human consumption).155 Therefore, we have to use water more efficiently. Especially, in irrigation, water has to be used most efficient level. Drip irrigation is one of the most feasible method to use water most useful level in agriculture. Drip irrigation enables to generate rural employment by allowing agricultural activities throughout the year. In addition, drip irrigation makes possible farmers to take up multiple cropping and enhances the cultivated area in a country where per capita net sown area is gradually decreasing due to increasing pressure of population on land. Moreover, the fear of drought is removed from the minds of the cultivators when the usage of the drip irrigation system increases. Usage of drip irrigation system allows cultivators to take high yielding of varieties of seeds, invest more capital inputs like fertilizers, and plant protection actions.16 Employment opportunities in many regions have increased after the development of drip irrigation system. Rising employment opportunities can occur because additional labor in planting and harvesting is needed for new land brought into production, for land that is being double cropped, or for industries that support agricultural production. One example of this occurred in Nepal. During the 1980s in the Nepal, total labor demand has doubled, improving productivity and welfare after the construction of a large public works project. Potential of production has increased by 300% and income 600%, leading to increased food security for the native population. In addition, a study in Kenya and Zimbabwe in 1997 showed that the average net increase in income from the drip irrigation was $150-$1000 per family farm.17
2.5) DRIP IRRIGATION IN TURKEY
The total area of Turkey is 77,945,200 ha, divided into 28,059,397 ha of arable lands, 21506,028 ha of pastures, 1,159,207 ha of water surfaces areas, 23,248,297 ha of shrubs and forests, 3,972,271 ha of residential areas. Of the arable land, 25.85 million ha is irrigable land and only 6% of the total arable areas are under pressurized irrigation systems (sprinkler and drip irrigation system). Turkey is a Mediterranean country which has devoted huge resources to implement the irrigation projects in the last three decades. However, the changes of implementing such new irrigation projects are decreasing gradually since, investment costs are perceived to be too high. Accordingly, the new situation of the Turkish economy necessitates irrigated agriculture to be more productive and cost effective.18 The conventional sprinkler irrigation and drip irrigation systems are more common among the Turkish farmers. Due to the global climate changing different sectors; agriculture, industry, municipality take some cautions on saving water. Therefore, a lot of research carried out Seyhan, Tarsus, and Harran Plain in Turkey using different irrigation systems on different crops for last three decades. As a result of these works, pressurized irrigation systems becomes widespread in Turkey. But the initial investment for the drip irrigation is considerably higher than the other systems of irrigation. For this reason, government’s subsidy into some extent is necessary for extensive use of drip irrigation system. Research results also showed that with the adoption of the drip irrigation system, consumption of irrigation water per unit of land has reduced by 30 to 50 percent at the same time the yield and quality of some crops have improved. 19 In order to try drip irrigation system in Altınekin district of the Konya where is the most rainless and most droughty place of the Konya, a hundred farmers planted wheat, barley, beetroot, haricot bean, lentil, and chickpea in 5700 decares.20 In the Altınekin district of the
Konya, with the use of drip irrigation system more than 3 million m3 water is saved. In addition, with the drip irrigation, savings reached to 46% in energy and 17% in fertilizer also, crop yielding increased by 25% and farmers totally made 673,000 ytl (new Turkish lira) profit in one year with the drip irrigation project. 21 In 2007, in order to use water resources most efficient level, Ziraat bank started to give interest-free credit for five years that is faced higher demand by the farmers. Ziraat bank will give totally 1 billion ytl (new Turkish lira) credit to spread the using of drip irrigation system which cost is between 500 and 1000 ytl per decare.22 Cost may change, according to the types of trees and plants, type of land, quality of materials and quality of water. Ziraat bank will collect interest-free credits in five years in five equal installments. Pipe producers say that given credit by the Ziraat bank increased the demand of drip irrigation system and sales increased by 50 %. Also, they predict that sales will double in two years.23 Incentive of the Turkish government for setting up the drip irrigation system increased the number of project about the drip irrigation system especially in Aegean, Mediterranean and Southeastern Anatolia region, approximately 86%. According to ministry of agriculture and rural affairs data, while there were 23 projects in 2005 that are supported by the government, projects rise to 302 in 2006 and in 2007 projects increased to 2012 extremely. In 2005-2007 periods, totally 2327 projects were supported and 65,955,000 ytl incentives are given by the government hence in 213,263 decares area sprinkler and drip irrigation systems were started to use and 31,978 farmers are benefited from the incentives of government.24
This study has investigated and discussed usage of drip irrigation system in crop production. Several broad conclusions can be drawn from discussion that may strengthen some of points made and provide a summary of this study. First of all, it should be clear that components of the drip irrigation is indispensable for the drip irrigation system to take advantage of the drip irrigation system and benefit from the system most effective level. Delivery system, filters, pressure regulators, valves or gauges and chemical injections constitute components of drip irrigation system. Secondly, there are two types of drip irrigation system. These are surface and subsurface drip irrigation system. Surface drip irrigation system is the most preferred system which is placed horizontally on the soil surface. In addition, in surface drip irrigation system supervising of drippers is very simple. Subsurface drip irrigation system is another type of drip irrigation system which is installed below the ground surface and water are delivered directly to the roots of the plants. Moreover, it is obvious that drip irrigation has some advantages and disadvantages. Drip irrigation provides increased water efficiency and saving, improved crop yields and quality, usage of saline water and improved fertilizer and other chemical application while initial cost, extensive maintenance requirements, clogging problem, and soil salinity constitute significant problems. Furthermore, it should be clear that using the drip irrigation system contribute to economy in some ways. Drip irrigation helps to create rural employment by permitting agricultural actions throughout the year. Thus, employment opportunities rise in many regions. Also, drip irrigation enables farmers to take up multiple cropping and thereby enhances the cultivated
- 10 -
area in a country where per capita net sown area is progressively falling due to increasing population on land. Finally, in Turkey, using of drip irrigation system in agriculture developed in last three decades. Some researches are executed in Seyhan, Tarsus, and Harran plain using different irrigation systems on different crops. As a result of these studies, pressurized irrigation systems becomes widespread in Turkey. However, government subsidy is important to increase the use of drip irrigation system due to the initial cost of the drip irrigation system is higher than other pressurized irrigation types. Thus, in 2007 Ziraat bank started to give interest-free credit for five years. In addition, incentive of government increased the use of drip irrigation system especially in Aegean, Mediterranean, and Southeastern Anatolia region.
- 11 -