以色列农业灌溉技术

Israeli Water Technologies for AgricultureThe Global Water Industry∙Water is one of the five largest markets in the world. It is estimated that over $350 billion is spent annually on generating and delivering water for human consumption, industry and agriculture.∙Expenditures are growing at seven percent yearly because of population growth, a higher standard of living, a decline in available ground water sources and climatic changes leading to conditions of worldwide drought.∙As water demands grow and sources shrink, new technologies are needed to increase the supply. This year alone over $50 billion will be invested in infrastructure and technological solutions in an attempt to meet the challenge of growing water demand. The global water shortage is generating attractive opportunities and serving as an incentive for growth of global business activity.Israel's Water Resources and SupplyAlthough the State of Israel borders the Mediterranean Sea, its climate is profoundly affected by the proximity of vast tracts of desert to the south and east.Precipitation is limited to the winter season, which extends essentially from November to March. Annual rainfall averages between 400 and 800 mm. in the north and west of the country, and declines sharply toward the south and east, dropping almost to zero. About 60% of the country is classed as arid and needs to be irrigated all year round to sustain agriculture, and even where precipitation is relatively high - in the northern and western parts - summer crops require irrigation between April and October. The more aridic areas are characterized by stronger solar radiation and higher levels of water evaporation from the ground surface.All over the country, but much more in the southern and eastern regions, the annual precipitation varies considerably from one year to the next. Under such climatic conditions the water supply picture is one of a fragile balance between supply and demand.Although most of the water resources are in the north and center, agriculture is being developed in the arid south and east. This reality has necessitated construction of an integrated water supply, which delivers water from the north to the south. The only significant surface freshwater reservoir is the Sea of Galilee, from which an annual average of 400 million sq. mtrs. is pumped to the south. The total annual water potential is roughly 2 billion sq. mtrs. Due to over-pumping and frequent droughts, the actual available annual water volume is 1.5 to 1.7 billion sqr.mtrs. The annual water allocation for agriculture is about one billion sqr.mtr, about one half of which is recycled and brackish water.Management of Water ResourcesThe main consumers of water are the agricultural, domestic and industrial sectors, with agriculture accounting for 60 - 72% of total water consumption.Water is regarded as a national asset and is protected by law. Users receive their annual allocation from the Water Commission. The entire water supply is measured, and payment is calculated according to consumption and water quality. About 90% of the fresh water resources have been incorporated into a single system that enables implementation of a uniform national policy of water production and regular supply to the different sectors of consumers (agriculture, domestic and industry).To conserve and protect Israel's water resources, currently exploited almost to the limit, severalmeasures have been taken by the Water Commission:1. Allocation of water quotas. Each sector is assigned an annual quota of water. The policy of allocation depends on the water balance, which may vary from one year to the next.2. Institution of sliding price scales varying according to sector. The individual consumer, be the farmer or city dweller, pays a higher price for water consumed beyond the allocated quantity. This incremental price policy encourages water saving.3. Recycling of sewage water. Increasing quantities of sewage water have been finding their way into the environment and endangering groundwater and other sources of fresh water. Brackish water is used for irrigation of salinity-tolerant crops like cotton. In several crops, such as tomatoes and melons, brackish water improves produce quality although lower yields are achieved.The use of reclaimed water for irrigation of edible crops requires a high level of purification. For that purpose, a unique technology – Soil Aquifer Treatment (SAT) – is now being applied in the densely populated Dan region at the Shafdan plant, a large-scale project for processing sewage to produce purified water. The process allows the same water to be used twice.The treated water is recharged to a nearby aquifer.Two major benefits result: a) percolation of the water through the soil layers provides an additional cleaning phase, and b) the aquifer serves as an underground reservoir for the recharged water, preventing loss by evaporation. Water is pumped off when needed, i.e., mainly in summer. About 100 MCM of this purified water is transported annually via a separate pipeline called the "Third Negev Pipeline" to the western Negev for irrigation. Due to the high degree of purity of the treated water, it can be used for all crops without any health risk.Additional plants for processing sewage water for irrigation are under construction or on the planning boards. It is expected that most of the water allocated for agriculture will eventually consist of purified effluents.Smaller-scale plants in the Negev provide treated sewage water for irrigation of fields located a short distance from the source of the effluent. This water is of inferior quality because of minimal treatment, and use is restricted to irrigation of crops such as cotton in the summer. Small projects of this type are reported to be highly cost-effective.While the benefits of recycling treated sewage water are indisputable - contributing to the water reserves by providing a substitute for the use of fresh water in agriculture and reducing pollution - there is one drawback which must be considered: domestic and industrial effluents are saltier than the fresh water supplied (due to detergents and salt in dishwashers and salt and other chemicals used by industry). As a result, the concentration in salts in recycled water is about twice that in fresh water, and irrigation with recycled water causes a gradual salination of the soil. The problem of soil salination can be overcome by regularly monitoring salt concentrations and by flushing out accumulating salts downwards from the soil layer where the roots are active. The option of desalinating treated effluents will have to be given serious consideration in the future.4. Exploitation of saline (brackish) water. Hydrogeological surveys have revealed that the Negev and the Arava valley possess considerable reserves of saline underground water with a variable concentration of salts. Many studies have been carried out to investigate whether this water can be used for irrigation. It was found that certain crops, such as cotton, tomato and melon, readily tolerate saline water (up to 7-8 dS/m electric conductivity, equivalent to salinity of 0.41-0.47% NaCl). For certain crops, there is no doubt that saline water can be used for irrigation in place offresh water. However, to minimize accumulation of salts around plant roots and facilitate leaching away of salts that do accumulate, it is essential a) to use drip delivery systems and b) to cultivate the plants in soil-less medium or light soils (sandy or loamy-sandy soil).The Israeli AdvantageBased on Israel's relative advantages, Israel can follow on its successes in communications, software, life sciences and advanced materials, and flourish in the areas of water technology and advanced water solutions. Israel's technology industry is currently ready for expansion.There are several factors that favor the development of a vibrant water technology industry in Israel:1. Existing trends in the global water market, including entry of the "global giants."2. The spirit of Israeli technological entrepreneurship. Since 2002, over 200 Israeli technology companies were sold to global firms for more than $6 billion. The technological achievements of Israel are well-known, and Israel is considered one of the world's leading high-tech centers.3. Existing water institutes.There are currently two academic institutes for water research. In addition, a government-supported fund dedicated to R&D for applied water technologies is planned.4.Chief Scientist programs. There are two techno-logical incubators dedicated to water technologies5. Israel has one of the most developed venture capital industries in the world.6. Israel's water technology industry is recognized for its advances, especially in the field of agriculture, as follows.Close Cooperation and InteractionThe fact that agricultural production continued to grow despite severe water and land limitations was no accident. It was the result of another unique Israeli phenomenon: a close and ongoing cooperation between researchers, extension advisers, farmers and agro- industries. Continuous, application-oriented research and development (R&D) has been carried out in the country since the beginning of the century. The result is cutting-edge agriculture in a country, more than half of which is defined as desert.The agricultural sector today is based almost entirely on science-linked technology, with government agencies, academic institutions, industry and cooperative bodies working together to seek solutions to problems and meet new challenges.Dealing with subjects ranging from plant genetics and blight control to arid-zone cultivation, lsrael's agricultural R&D has developed science-based technologies which have dramatically enhanced the quantity and quality of the country's produce.The key to this success lies in the two-way flow of information between research personnel and farmers. Through a network of extension services (and active farmers' involvement in all R&D stages), problems in the field are brought directly to the researcher for solutions, and scientific results are quickly transmitted to the field for trial, adaptation and implementation.The drive to achieve maximum yields and crop quality has led to new plant varieties, to breeding of improved animal species and to a wide range of innovations in irrigation and fertigation, machinery, automation, chemicals, cultivation and harvesting. Many of these innovations are also exported.The extension services offered to farmers by the Ministry of Agriculture have been instrumental in the introduction to the farmers of advanced agrotechnologies, new varieties and properagricultural management. The existing close cooperation between farmers, extension officers and researchers is also the main factor contributing to the success of farming in the arid Negev. Development of Unique Agro-TechnologiesWater constraints and varied climate have stimulated the development of unique agro-technologies, based on high quality standards according to updated international production and food-safety regulations. Irrigation technology, fertigation, development of greenhouse equipment, seed and livestock propagation, fertilizers and pesticides have enabled Israeli agriculture to prosper in adversity. In addition, farmers have learned to develop high value-added and innovative farm products that enable them to compete in markets with lower-cost producers. Water management, recycling, desalination and transportation in the National Water Carrier have enabled the country to overcome drastic shortages.Israel as an Effective Model for Arid Zones and Exporter of Agricultural InputsIn the light of the review presented here, it is suggested that Israel can serve as an effective model for many regions afflicted by similar arid conditions.Because Israeli farmers and scientists have had to contend with a difficult environment and limited water resources, their experience is especially relevant to the developing world.Its success lies in the determination and ingenuity of farmers and scientists who have dedicated themselves to developing a flourishing agriculture in a country which is more than half desert, thus demonstrating the world that the real value of land is a function of how it is utilised.The close cooperation between the R&D and the industry led to the development of a market oriented agri-business, that exports agro-technology solutions world wide.Water and Irrigation1. Irrigation TechnologyIsrael is the world’s most advanced use r of agricultural irrigation, with half of all agricultural land under irrigation.The irrigation industry in Israel was a pioneer in developing innovative technologies and accessories like drip irrigation, automatic valves and controllers, media and automatic filtration, low discharge sprayers and mini- sprinklers, compensated drippers and sprinklers.The Computer – controlled drip irrigation saves huge quantities of water and enables the supply of fertilizers with the irrigation (fertigation).The innovative irrigation industry has a worldwide reputation and more than 80% of its production is exported.One of the principles of good agricultural practice is to provide developing plants with an adequate water supply - i.e., to avoid excess standing water and to prevent exposure to water shortage. Excessive amounts of water can cause poor aeration of the root system leading to inhibition of plant development, or wasteful percolation through the soil beyond the volume of the root system, or both. A water deficit places the plant under stress and interferes with its normal development. Avoiding water stress is particularly important in arid regions, where high solar radiation and low humidity enhance evapotranspiration (the process of loss of water from the ground surface and plant canopy).Efficient use of water is crucially dependent on advanced irrigation technologies, and nowhere more so than in arid-land farming. Until about 50 years ago, crops in this country were irrigated by surface (flood and furrow) irrigation. Surface irrigation is possible only when the ground is leveled and the soil type enables slow or moderate percolation of the water.Under arid conditions, surface methods of irrigation lead to severe loss of water by evaporation and by percolation beyond the developed root system, especially in the stages of germination and early development; moreover, between irrigation sessions the plants are exposed to stress. Another negative aspect of surface irrigation under arid and semiarid conditions is the process of soil salinization. The prevailing high temperatures and low humidity cause intense evaporation from the ground accompanied by accumulation of salts in the upper layers of the soil. The soil gradually becomes unfit for cultivation, both because of the destruction of the soil and due to the direct effect of the high concentration of salt on the plants. Vast areas in arid and semiarid regions of many countries affected by salinization have indeed had to be abandoned. Pressurized irrigation with sprinklers, introduced about 50 years ago, contributed much to modernizing agriculture and increasing water use efficiency. However, from the standpoint of agriculture in arid and semiarid regions, the most important development has been the introduction of drip irrigation. Drip irrigation was developed in Israel and introduced into Israeli agriculture less than 35 years ago. Since then it has been disseminated all over the world with great success.Advantages of Drip irrigation∙Water is discharged uniformly along the lateral (pipe fitted with drippers) even on moderately sloping terrain. The invention of compensated drippers enables uniform irrigation of steeper slopes and long distances.∙Fertilizers can be supplied to the plant via the drippers together with the water (fertigation).∙Water and fertilizers are delivered directly to the root system rather than to the total area of the field, thereby economizing on both water and fertilizers.∙The quantity of water delivered can be optimized to fit different soil types, avoiding percolation of water beyond the root zone.∙The emergence of weeds is minimized.∙Exploitation of poor quality water (saline water or effluents) is made possible.∙Drippers with a given discharge of water (liters per hour) can be installed at any spacing to accommodate the needs of any crop.∙Drip irrigation is the most efficient method as regards water saving. Since the drippers emit the water directly to the soil adjacent to the root system, which absorbs the water immediately, evaporation to the air is minimal. This effect is especially important under the conditions prevailing in arid zones.∙In irrigation by sprinklers or by surface methods, evaporation is enhanced by winds; by comparison, in drip irrigation the impact of winds is minimal.∙Drip irrigation, unlike sprinkler irrigation, makes it possible to utilize saline water by eliminating direct contact between the water and the leaves, thus avoiding burns.∙Drip irrigation causes salts to be continuously washed away from the root system, avoiding salt accumulation in the immediate vicinity of the roots when irrigating salinized soils or irrigating with saline water.∙Drip irrigation allows the use of sewage water because the water is delivered directly to the ground, minimizing health risks.∙High-quality drip irrigation equipment can last for fifteen to twenty years if handled properly.A new, modified drip irrigation system has recently been developed for small-time farmers. Known as the "family drip system" or the "gravitation drip system", it is designed for use where both the water supply and the financial means are very limited. A simple container - such as a barrel or a hand-built container coated with a plastic layer - is filled with water and positioned about one meter above the ground. By opening a valve, the water flows by gravitation into the drip system. The container can be refilled using a manual pump, and fertilizer may be added to the water, as in the conventional drip system.Water use efficiency (WUE), is the ratio between the amount of water taken up by the plant and the total amount of water applied. Studies show that while WUE is about 45% in surface irrigation and 75% in sprinkler irrigation, in drip irrigation it is about 95%. Consequently, it may be concluded that drip irrigation has many advantages over other methods of irrigation and that it is significantly superior to surface and sprinkler irrigation in regard to water saving, especially under conditions of limited water supply.The innovative irrigation industry has a worldwide reputation and more than 80% of its production is exported.2. Recycling of Drainage WaterIn soilless media culture, the typical leaching fraction applied in Israel to remove accumulated salt is between 3- and 50%. As a result, one third to one-half of the applied water drains out, carrying 130 mg/l nitrogen, 2- mg/l phosphorus, and 140 mg/l potassium as well as natural salts. Approximately 1,000 kg of nitrogen, 1,600 kg of chloride and 800 kg of sodium are leached from one hectare of substrates, which are a potential polluting factor of more than 100 million sq.mr. of groundwater. In the last few years, around 25% of greenhouses with soiless substrates shifted from open to closed irrigation systems. This shift is even more impressive in rose production, where drainage water is recycled in over 50% of the greenhouses.Recycling of nutrients by reusing water drainage in soiless cultivation appears to be the most logical solution: approximately 50% of water and fertilizer inputs are saved, because of reduced tap-water supply and improved nutrient availability to the plants. The potential pollution of the aquifer from the open irrigation system is reduced. The transition from an opened to closed irrigation system unexpectedly resulted in yield increase and higher fruit/flower quality, due to the higher fertigation control and monitoring applied in the new technology.Future TrendsThe expanding urban population, as well as political developments, will likely further reduce the fresh water supply for agriculture. The solution lies in the desalination of brackish water and high-level water reclamation. A more significant part of annual crops will be grown under cover, where recycling will become routine. The concepts of ultra-low irrigation rate and vegetable monitoring should be further examined for their contribution to higher efficiency of water utilization.ExportAgricultural export (fresh and processed) for 2005 reached $1,680 billion, 4.6% of the country's total exports. Exported fresh produce amounted to $1,024 million, mainly to the European Union, while exported processed food products totaled $656 million.In addition, a total of $1.9 billion of agricultural inputs were exported (2006). This figure is the outcome of advanced agricultural technology, which has created a thriving industry of sophisticated industrial inputs. Hands-on experience in local agriculture serves as a laboratory forthe development, design and manufacture of new input technologies.Turnkey projects, consultancy and know-howIncreasingly, Israeli agrotechnology companies join forces and supply turnkey projects for both crop and livestock development programs.Multiple skills, talents and experiences are enlisted to provide integrated solutions that embrace soil, water, additives, plant and livestock varieties, equipment and structures. The results are measured in improved yields produced at lower costs, a win-win situation in a resource-stressed world.。