Potential Reduction in Irrigation Water Through the Use of Water-Absorbing Polymers in Agriculture
Introduction
The United Arab Emirates (UAE) is made up of seven emirates federations. These federations are Abu Dhabi, Dubai, Sharjah, Ajman, Umm Al Qaiwain, Ras Al Khaymah, and Fujairah. Among these emirates, Abu Dhabi is ranked as the largest emirate. Moreover, Abu Dhabi city acts as both the capital of the country and that of the emirate (Al Abed & Hellyer, 2001). The total area of the United Arab Emirates is estimated to be 83,600 square kilometers. From an ecological point of view, the UAE could be separated into three categories namely the sandy or desert area, the northeastern mountain areas, and the marine coastal area. The UAE has also been hard hit by desertification since 80 percent of the area falls under deserts. Over recent times, the area under agriculture has continually increased with a major focus on annual and permanent crops (Goudie & Al-Farraj, 1999).
The climate in the UAE and Arid Region
Since 80 percent of the area is under the desert, the UAE has a vast arid region with summer temperatures being very high (Shanan & Tadmor, 1979). However, most of the population lives in the coastal area which is characterized by high humidity and heat. For instance, during summer, temperatures usually rise to reach 46 degrees Celsius coupled with a humidity of 100 percent. The experiences in winter are a bit mild with temperatures dropping between 13 and 23 degrees Celsius (Riegl, 2003). When advancing towards the interior desert region of the emirates, temperatures do record a high of 50 degrees Celsius and can also fall up to about 4 degrees Celsius. This, therefore, implies that the interior desert region experiences very hot summers and very cool winters.
On average, the annual rainfall received in the United Arab Emirates is about 78 mm with the southern desert around Liwa receiving about 40 mm (Al-Farraj, 2005) which is not sufficient to sustain agricultural activities since the area loses a lot of water through evaporation while experiencing very little rain. On the contrary, the northeastern mountains do receive a high of about 160 mm of rainfall. Precipitations are also experienced in the emirates which range from 9 to 19 days in a full year. Significantly, a bigger percentage of the annual rainfall received in the emirates happens during the winter period which accounts for over 80 % (percent) and is normally received between December and March (Alsharahan & El-Sammak, 2004). The Emirates also experiences Spring Season which is normally characterized by rainfall which is infrequent and normally accompanied by isolated thunderstorms. This season occurs between April and May.
Summer in the Emirates is experienced at some point between June and September. In summer, rainfall is scarce and there are isolated thunderstorms that accompany sea breeze fronts which occur rarely. The Inter-Tropical Convergence Zone (ITCZ) on some rare occasions shifts resulting in rainfall in this part of Emirates (FAO 2008). The emirates also experience autumn from October to November which is perceived to be a climate with weather conditions that are more stable and settled.
Importance of agriculture in the UAE
The importance of agriculture in any economy cannot be overlooked, UAE being among them. Despite a smaller percentage of the total land put under agriculture and forestry, approximately 1.5 % (percent), UAE has continued to increase the amount of land devoted to agricultural activities through various efforts and initiatives by the government (Al Abed & Hellyer, 2001).
First, the agricultural plots were granted for free to UAE citizens who were interested in venturing into farming. This was aimed at ensuring that many people would be able to have arable land and hence boost the production of food crops in the country as they continually gained support from the government. This also helped to ease pressure on the need to create more employment opportunities (Al Abed & Hellyer, 2001). Also, the preparation and leveling of land allocated to the citizens were done by the government for free so that the farmers could have an easy time with the farming activities. Depending on which type of agricultural activity one wanted to venture into, the government prepared and leveled land for that purpose at no cost.
Besides, farmers in the UAE also received farm inputs like fertilizers, insecticides, as well as seeds from the government at half the price (Al Abed & Hellyer, 2001).
This encouraged more people to take on agricultural activities to help boost food and animal production in a country that is adversely affected by weather patterns, a situation that has led to the desertification of the majority of the land. This also ensured that the farmers invested little and gained more from agricultural activities (Al Abed & Hellyer, 2001). Also, since this form of farming does not rely on rainwater, water wells were drilled by the government for free to help carry out irrigation and boost other water usage activities in agriculture. This was over and above the free technical services that the farmers received from various government services, including the installation of water pumps. Thirdly, in 1978, the government formed a credit line for agriculture aimed at boosting the farmers financially such as granting loans to farmers. This way, farmers were in a position to buy water pumps, build greenhouses, as well as setting up irrigation systems. To make it more appealing to the farmers and increase the uptake, the loan did not attract any interest (Al Abed & Hellyer, 2001). This lured many people into taking up agricultural activities in the UAE. To ensure that farmers had a ready market for their produce, the government intervened and secured a market for the produce. It is important to note that majority of the small-scale farmers in the UAE do not experience harsh foreign competition. This is realized through the establishment of a policy that makes sure that all the farmer’s produce is purchased at favorable prices. This provided a ready market for the produce (Al Abed & Hellyer, 2001).
Among the important role agriculture plays in the UAE include the following:
Increased food production
With the vast land of UAE being under deserts, the country heavily relied on imported food to meet the demands of its population. This meant that the emirates spent a colossal amount of its foreign earnings to import food for its population. In the late 90s, the country was importing up to 70 % of its food requirements. However, as time went on and the provided incentives by the government, more people got into farming which helped increase the level of food production locally (Yazdani & Abas Akbari, 2007).
This helped the government to significantly cut its expenditure on food imports due to the food being produced locally. For instance, poultry farming met about 70% of the requirements of eggs while also providing about 45 % of the poultry meat required locally. Besides, some of the locally grown vegetables like eggplant and tomatoes, among others, meet the daily needs of the population in the UAE. This helped to boost food security in the UAE (Zohuriaan-Mehr & Kabiri, 2008).
Source of income for farmers
Agriculture has also become a dependable source of income for farmers in the UAE. Ranging from the domesticating and selling of poultry meat, eggs, fish farming, dairy farming that helps boost milk production in the region, date palms, and fruit crops such as mangoes and citrus. This was also aided by the fact that the government put a policy in place that ensured the farmers were protected from the harsh foreign competition (World Bank, 2005). This made it possible for local produce to be bought at favorable prices locally hence driving away foreign competition. This provided a steady income for the people engaging in agricultural activities since there was a ready market for their produce attributed to the high demand for food crops and other agricultural produce.
Source of employment opportunity to citizens
Agriculture in the UAE has also helped reduce the level of unemployment in the country. This has been made possible by several initiatives with incentives by the government to lure many people into farming. Such incentives include the allocation of agricultural plots for free to UAE citizens for farming, subsidizing the cost of farming inputs, setting up a credit line for farmers that do not attract interest, and free mechanical support for those venturing into agriculture. For example, at the onset of the 1970s, an estimate of 4,000 farmers was present in the UAE, but after the incentives were established the incentives the number appreciably increased to an estimate of 18,265 in 1988. This implies that a significant number of UAE citizens were drawn into agricultural activities (World Bank, 2005). This ensured that the farmers concentrated on agricultural activities mostly full time hence they became self-employed. This helped to ease the rate of unemployment in the country as it provided a steady source of income.
Boost of afforestation efforts
The UAE has also ventured into environmental conservation efforts by trying to plant trees where none existed before. Citizens engaging in farming are also encouraged to plant trees in the portions allocated to them. This is an attempt by the government to help protect the environment in areas where agricultural activities are taking place and also to help keep desertification at bay (Salloum, 2002). A case in point in the tree planting program that involves the distribution and planting of trees in schools, public offices, as well as residential areas. Most of the tree varieties are prepared and grown locally in seedbeds before being transplanted to different places. Agriculture has therefore played a major role in boosting afforestation efforts by the government with the support of citizens engaging in farming activities.
Improvement of agriculture in the UAE
Modern-day agriculture calls for continuous improvement of the farming activities that ensure maximum yield with low input. This can be achieved after extensive research aimed at improving the current agricultural techniques being applied to bring about efficiency and effectiveness (Al Abed & Hellyer, 2001). Furthermore, motivation for farmers also plays a key role in helping to improve agriculture. In the UAE, the government has tried to improve agriculture through the following ways:
Provision of incentives to citizens engaging in agricultural activities
The government of the UAE has achieved this first through the allocation of agriculture plots to UAE citizens for free. Also, the government prepares the land for free and also ensures that the farm inputs bought by farmers are subsidized such that farmers buy them at half the cost. This has helped to lure many people to engage in agricultural activities like poultry farming, fish farming, and crops like tomatoes, cabbages, and date palms (Bainbridge& Mac- Aller, 1995). The incentives have made agriculture to be an attractive activity to the citizens which goes a long way to become a source of income from the sale of the produce.
Extensive and improved irrigation methods
Since the average rainfall received in the UAE cannot sustain agriculture, the government has invested heavily in irrigation activities for farmers. Initially, traditional irrigation methods were employed in farms which saw little effectiveness in terms of water retention and improved yields (Azzam, 1980). However, as time went by, more effective and efficient irrigation methods were devised and adopted which has seen an increase in production and also helped to make good use of the scarce water. The traditional irrigation methods led to a lot of water wastage and did very little to achieve the objective of irrigating large portions of land with little water available. This is evidenced by the move from methods such as surface and drip irrigation to the current solar irrigation (Bakass & Lallemant, 2002).
Provision of agriculture extension units and research
To boost agriculture, the government of UAE has invested heavily in agriculture extension units and research. This is to help come up with better methods and techniques of farming ranging from different crop straits that are more drought-resistant to different farming methods that bring about high yields within a short period (Bhat et al, 2009). Agricultural research stations have also been increased to provide farmers with the best advice. Experimental farms have also been set up to help carry out practical research concerning certain farming methods and also testing different seed varieties (Azzam, 1980). This aims at ensuring that before farmers make use of the current technology available, the government puts them to test before rooting for their adoption. Where a technique or method is useful, farmers have been advised to adopt the same. On the contrary, technologies that have failed during the testing stage have also not been adopted hence saving farmers’ time and money.
Water usage challenges in the UAE
Availability of sufficient water poses a major challenge in the UAE. The region mainly relies on two sources of water to support its activities. The first source is the groundwater while the other source is the desalinated water coming from the Arabian Gulf. Two-thirds of the water supplied is from the groundwater while the remaining third comes from the desalinated one (Al Abed & Hellyer, 2001). Agriculture and forestry in the UAE mainly rely on groundwater while the desalinated water from the Arabian Gulf is used for residential purposes, commercial purposes, and amenity irrigation. The supply of renewable freshwater in the UAE ranks among the lowest in the world which contrasts with its high per capita consumption posing several challenges to water usage including:
Rapid population growth
The UAE experiences a rapid population growth that is posing a challenge to water usage. This means that there is a surge in demand for water by the citizens as their numbers are increasing at a fast rate. For instance, in 1975, the UAE had an estimated population of half a million people but by 2010, the population had risen to approximately 8 million 2010. To sustain this population, there has to be a lot of effort to be put in place to increase the supply of water to meet the demand (Elhiraika & Hamed, 2002). However, the much being done by the government is not enough to supply adequate water to the entire population. This shows a significant rise in the population of UAE posing water usage challenges.
Inadequate conservation measures among residents
Of the little water that is supplied for use to residents, most of it goes to waste due to the lack of conservation measures by the residents. This is also coupled with the fact that water from desalinization undergoes a process and is therefore not in constant supply if there happens to be a hitch in the desalinization process. Residents themselves do very little or none at all to conserve the water that is available for use. This is made worse by the rise in affluence where the residents prefer a high-class life hence the need for more clean water for use in their homes without efforts to recycle or conserve the same. This poses a great challenge for water usage in the UAE.
Inefficiency in the traditional irrigation methods
A vast portion of the land under agriculture in the UAE is facilitated by irrigation thereby accounting for a great percentage of the water consumed from the groundwater. The methods used for irrigating the lands have led to much wastage of the water due to their inefficiency. Such methods include sprinkler irrigation that sprays water over a particular area with crops (Al Abed & Hellyer, 2001). Wastage comes in where the waterfalls on an area that has no crops. Furthermore, the adverse climate that is mainly hot during summers exacerbates the situation since the sprinkled water is lost through evaporation before it is utilized by the crops, in addition to the evapotranspiration process. This, therefore, culminates into a cycle of wastage.
Different irrigation processes similar to the UAE
Surface irrigation
Surface irrigation is the most widely used method in the UAE and other arid regions with similar climate characteristics to the UAE (Lioubimtseva, 2004). This is because it does not require high capital costs such as the purchase and installation of irrigation machines and systems (Evenari, 1975). Nonetheless, the drawback associated with a surface irrigation system is that it is considered quite labor-intensive. This method facilitates the spreading of water into the farm, thereby easing the process of water infiltration into the soil. In this irrigation method, the field or farm may be made completely wet, which refers to a basin and border irrigation (Bhat et al, 2009). The field may also be wetted partly due to corrugation and furrow irrigation. When the water layer moves during the irrigation process, this is called flow irrigation but when the water is stagnant during the irrigation, this is called check irrigation.
Border irrigation calls for sufficient land preparation to allow for the distribution of the water. The land is followed by division into parallel strips that are considerably long and narrow. Moreover, the stripes are usually separated through the use of earth or soil banks. The arrangement of the strips is done lengthwise bearing in mind the direction where the land has a maximum gradient (Bhat et al, 2009). Each of the irrigation strips has a high point location where irrigation water is opened or released to flow downwards the parallel strips to moist the soil.
Basin irrigation is also another type of surface irrigation. Under this method, the construction of cross-banks is done at regular intervals down the slope on the contours and a channel or pipeline ensures each basin is supplied with water. The cross-banks are normally spaced depending on how steep the slopes are longitudinally (Buchholz & Graham, 1997). Once one basin is filled with the irrigation water, it then flows down onto the next basin and in the process, soaking the soil it is flowing over.
Sprinkler irrigation system
This method of irrigation is almost exactly the opposite of the surface irrigation system. This is because it is less labor-intensive as compared to surface irrigation but it requires high capital investment. This irrigation system has four basic components that include sprinklers, lateral lines, a pumping unit, and main lines (Buchholz & Graham, 1997). Water is normally pumped using the pumping unit which then flows to the main and lateral lines before reaching the sprinklers. The sprinklers are normally located where the crops are which then lets out water in jets covering a certain area (Buchholz & Graham, 1997). Sprinklers are usually more than one and are placed strategically surrounded by the crops to ensure maximum efficiency. This irrigation system can suit a wide range of crops, soils, and topography. Due to the high capital costs that come with this method, it is normally applied to crops that yield high returns to help maintain the systems. One of the main benefits of this kind of irrigation system is that it can be conducted on shallow soils and irregular topography (Buchholz & Graham, 1997).
Furthermore, highly permeable soils or sand can also be irrigated through deep percolation without wasting water hence also preventing soil erosion (Kahn, 1983). This irrigation method can also adapt to small applications in terms of land size and also can be used to spray soluble herbicides and fertilizers.
Some of the limitations of this method include the initial high capital demand for purchasing the equipment, operation costs that are high as compared to surface irrigation, and energy requirements to facilitate the pumping unit. Furthermore, the distribution of water from the sprinklers is affected by the wind which may end up irrigating certain areas that were not intended hence leading to wastage of water. Besides, some crops are susceptible to leaf damage due to sprinkled water (Reddy & Rao, 1980).
Optimal irrigation processes in the UAE
The UAE is at crossroads considering its adverse weather conditions that result in water scarcity, the surging population numbers, and the rising demand for water by its citizens (Al-Assam & Sattar, 2005). With a greater percentage of the water available being channeled to irrigation to sustain agriculture, there is a need to find optimal ways of utilizing the available water by spending little to achieve more. This is also accentuated by the need to have renewable sources of energy due to the depleting natural gas and oil reserves which may affect energy supply in the future (Crown Prince Court, 1999). This has led to the adoption of optimal irrigation systems which include the following:
Solar-powered irrigation system
This has been rated as the most effective and efficient irrigation method suited for an area that has an arid climate to support agriculture. Taking cognizance of the diminishing oil and natural gas deposits in the UAE, there is a pressing urge to shift dependence from non-renewable sources of energy to renewable sources (ACEEE, 2001). Solar energy, therefore, proved to be the most effective to be relied on bearing in mind the climatic conditions that create room for tapping the solar energy and the pressing need to shift to renewable energy sources (Dixon & Simanton, 1980). Using solar-powered irrigation also ensures that wastewater is utilized for different landscaping needs together with having a positive impact on the environment since it produces no pollution as opposed to diesel-run engines.
With this technological advancement, solar panels are connected to water pumps such that the solar rays from the sun are trapped by the solar panels and the energy is converted to run the water pumps which eventually do the irrigation (ACEEE, 2001). Before the installation of the solar panels, a feasibility study was done to determine whether it would suit landscaping irrigation. This was done by collecting weather data, carrying out a site analysis, reviewing effective solar panels and the possible mounting solutions. This was finalized by developing an economic model for the same to prove the viability of the project (ACEEE, 2001).
Though this irrigation system has not been extensively used, its adoption is in the infantry stages bearing in mind that its testing and launch was done first by applying it to roundabouts to see its practicability (Al Abed & Hellyer, 2001). Undoubtedly, solar-powered irrigation is coming in as the next efficient and effective way of landscaping irrigation and thus a major boost for agriculture while at the same time cutting on the cost that would have been used to run the diesel engines that supply water pumps with power. Moreover, this irrigation system is in sync with promoting a green economy for the UAE.
Localized Irrigation
Localized irrigation comes in like a method that is less labor-intensive as compared to the widely used surface irrigation. On the other hand, this irrigation system demands high initial capital input. What can be observed across the wide spectrum of localized irrigation types is the application of water frequently at low rates which helps to keep the soil surrounding root areas close to field capacity (Al Abed & Hellyer, 2001). In this way, crops are supplied with water achieving increased uniformity in the supply which helps to preserve the soil structure. The irrigation water is also saved on a great account due to reduced evaporation. Furthermore, water and nutrients quantities reaching the crops can also be controlled to release the correct amounts.
On the other hand, this irrigation method has also its shortcomings. First, the small drippers may be obstructed or blocked by water impurities, chemical and biological formations may start appearing on the drippers. Furthermore, this type of irrigation normally creates soil that is normally permanently saturated or nears saturation which favors the development of animal and plant pests together with the accumulation of saline (Al Abed & Hellyer, 2001). Localized irrigation has two main types which include the following:
Drip or trickle irrigation
This method applies water to the soil directly flowing at low rates around the plant but frequent enough to keep the soil surrounding roots at field capacity or near field capacity. The irrigation water is normally filtered so that water impurities and other deposits do not accumulate in the drippers and lines (Al-Assam & Sattar, 2005). This irrigation method can also be used when applying pesticides and fertilizer to the plants. The selection of intervals between irrigations may vary depending on several factors such as the evaporative demand and soil structure. Soils that are very coarse having a water holding capacity that is small, irrigation is normally done for a short period daily bearing in mind the time when plants utilize water most.
For soils that are sandy and light, irrigation intervals normally vary from about one to four days. For loam soils that are heavy and containing some clay, the watering interval normally varies between two to eight days (Al-Farraj, 2005). On the same note, the duration of applying water also varies depending on the soil type; heavy soil will be watered for long (between 10 to 16 hours) while light soil will be watered for a relatively shorter duration (between 6 to 10 hours) (Al-Farraj, 2005).
Drip irrigation has several advantages including ease of management of the irrigation system since it does not hamper other farm operations which makes it possible to access the field at any time. Moreover, this method of irrigation does not lead to leaf burn since the water does not fall on top of the plant or leaves but rather supplied to the soil and especially around the root areas. The application of drip irrigation also ensures that poor soils are better utilized. For instance, heavy soils may not work well with sprinkling while soils with a very light texture will also fail to work well with a variety of surface irrigation methods (Al-Farraj, 2005). To sum it up, due to the high efficiency and low working pressure requirements, the costs attributed to pumping are fairly low.
Micro -spray or Micro-jet irrigation
This is another type of localized irrigation which slightly differs from drip irrigation. The slight difference is that this method does not have the moving spinner that helps to distribute water droplets to the targeted area (Edstrom & Schwankl 2002). It operates by having water from a fine jet being directed onto a specific irrigation area. This mode of irrigation is commonly applied to young trees and new plantings.
Different types of Polyacrylate that can hold water for irrigation purposes
Polyacrylate refers to a polymer of salt mainly composed of acrylic acid (Buchholz & Graham, 1997). Polyacrylate has come as a milestone development in the irrigation of crops especially in the arid regions to complement the contemporary irrigation methods such as drip irrigation. The ability of the Poyacrylates to retain water is what makes them score high in the irrigation process as they do not lose water easily (Al-Assam & Sattar, 2005). Coming in as polymeric soil conditioners, the polymers were mainly developed to help boost physical properties of different soils through enhancing the water holding capacity of the soils, increasing efficiency in the use of water, increasing permeability of soils and infiltration rates, cutting down on the frequency of irrigation, reducing the tendency to compact by the soils, checking on water run-off and eventually soil erosion and generally boosting plant performance especially in the arid regions (Lentz, 2003).
History of the water-absorbing polymers
Water absorbing polymers which are also commonly referred to as water crystals could be traced back to the 1960s. Union Carbide is considered to be the company to have used water-absorbing polymers to undertake irrigation by growing plants in an arid region as stated by Abd EI-Rehirn and Hegazy (2004). The initial prototype of the water crystals developed proved to be economically inefficient for home use because they were quite expensive. With time, the initial technology was gradually enhanced to come up with the water-saving hydrogels that are commonly used in agriculture for irrigation especially in arid areas due to their ability to absorb a lot of water and release the water slowly when required by the plants (Huttermann & Reise, 1999).
Different types of Poyacrylates could be used to hold water for irrigation purposes such as sodium polyacrylate. The sodium polyacrylate is a chemical polymer that is largely used across most of the consumer products essentially because of its natural ability to absorb moisture when exposed to water (Abd EI-Rehirn & Hegazy, 2004). It is also due to this inherent characteristic that also qualifies it as an important component to be used in agriculture for irrigation purposes. This polymer is made up of multiple annular chains largely of those of acrylate compounds characterized by a positive charge of anion. This gives it the tendency to attract water-based molecules. This, therefore, qualifies sodium polyacrylate as a super absorbent polymer or compound (Mohammad & Kourosh, 2008). On the other hand, the inhaling of sodium polyacrylate is associated with damages to the skin, eyes, and lungs, owing to its high toxicity (Mohammad & Kourosh, 2008). This polymer is at length used in agriculture by introducing it into the soil specifically in most potted plants. This way plants get to retain high moisture levels, and this effectively helps to increase the plants’ water reservoir.
It can absorb water many times its weight (approximately 200 to 300 times it’s mass when put in water) and also retains the water for a long time (Flannery & Busscher, 1982). This, therefore, increases the length of irrigation intervals since the root areas of the plant will be in a constant supply of the required moisture. This saves much on the water that would have been used to irrigate and also the cost of running diesel engines for pumping the irrigation water (Al-Assam & Sattar, 2005). Its use has been also extensively applied in the flower industry where florists use it to preserve water to retain the freshness of the flowers before being taken to the distant markets (Salloum, 2001).
Potassium Polyacrylate
Potassium Polyacrylate is also another polymer that is applied in agriculture for irrigation purposes due to its water retention capability.
How potassium Polyacrylate works in irrigation
Potassium Polyacrylate is also a water-absorbing polymer. It works by taking in high quantities of water and slowly releasing the water molecules through the osmosis process (Abd EI-Rehirn & Hegazy, 2004). This makes the water to be easily available for the plants resulting in highly efficient water utilization be it in potted plants or for landscaping purposes of irrigation. Apart from storing water and significantly cutting on the water used for irrigation, potassium polyacrylate also helps to improve soil porosity and aeration since it takes space in the soil (Abd EI-Rehirn & Hegazy, 2004). In a more detailed explanation, below are the functions of potassium polyacrylate and how it works:
Water absorbing and water releasing function
Potassium polyacrylate is made with a strong and high capacity of water-absorbing and water absorbency. It is estimated that the polymer can absorb an estimate of 400 – 500 times its weight in pure water. When it comes to actual production, the potassium polyacrylate can absorb quickly and store the irrigation water in addition to rainwater and thus forming a micro-reservoir (ACEEE, 2001). The polymer then depends on the micro-reservoir to carry out the recycling of absorbing irrigation water and rainwater when it is available and releasing it when there is no water from irrigation and rain (ACEEE, 2001).
The polymer is estimated to have a water retention capacity of between 13 and 14 kg/cm2 compounded with a strong resistance to external physical pressure. This means that the moisture absorbed by potassium polyacrylate can hardly be lost through general physical methods which therefore effectively prevent leakage, loss, and evaporation of the moisture (Abd EI-Rehirn & Hegazy, 2004). On the other hand, the general systems of plant roots have a water-absorbing capacity of between 16 and 17 kg/cm2 which means that roots will absorb easily the moisture needed from the existing established micro-reservoir whenever a shortage of water occurs(Abd EI-Rehirn & Hegazy, 2004).
Fertilizer maintenance and absorption function
Traditional methods of applying fertilizer to crops commonly make the fertilizer volatilized, decomposed, and usually wasted together with the moisture in instances where the fertilizers fail to be absorbed by the plants (Ahmed, 1990). Apart from absorbing 400 to 500 times of irrigation water, potassium polyacrylate can also absorb approximately 100 times of urea (self-weight). This, therefore, implies that the fertilizer to be applied to the plants can effectively be utilized by fixing it in the soil for slow release (Al-Assam & Sattar, 2005). This will greatly reduce the loss of the fertilizer while also ensuring that the fertilizer period is effectively prolonged. This qualifies potassium polyacrylate as having a dual function of fertilizer maintenance and fertilizer absorption.
Soil improving function
Potassium polyacrylate also plays a key function in improving the soil. It does this by making the soil to form a ventilated, soft and aggregate porous structure since its particles normally undergo expansion after absorbing water and also shrinkage when they release the water (Ahmed, 1990). This essentially meets the crops demand regarding moisture, enhances the permeability capacity of clay soils, and improves the capacity of sandy soils to retain moisture. Moreover, after doping the potassium polyacrylate into the soil, the polymer helps to boost the moisture content of the soil, minimizes thermal conductivity, helps reduce daytime soil temperature by approximately 1 to 4 degrees Celsius and also raise the soil temperature at night by approximately 2 to 4 degrees Celsius (Abd EI-Rehirn & Hegazy, 2004). This will, in turn, reduce the difference between daytime and night temperature which favors soil improvement and also the growth of the plants under irrigation.
High safety function
Potassium polyacrylate is a product that is eco-friendly with a neutral potential hydrogen value and does not release any unhealthy matter (Ahmed, 1990). The polymer is also nontoxic and causes no harm to the environment and plants. Furthermore, the polymer cannot be washed away or run off when it comes into contact with rainwater and can be degraded naturally hence reducing it to ammonium nitrogen, small quantities of potassium ions, and water after one year hence branding it as an active player in soil improvement
Importance and application of potassium polyacrylate
Due to the unique characteristics of the potassium polyacrylate, the polymer can be used for different purposes including:
Irrigation
Irrigation carried out especially in arid regions using potassium polyacrylate has proved to be very effective. Once the polymer is mixed with the soil, it will significantly reduce the amount of water that can be lost during evaporation. Because it can absorb water in large quantities, many times its self-weight, potassium polyacrylate will store the irrigated water for long durations which then reduces the frequency of irrigation (Abd EI-Rehirn & Hegazy, 2004). The polymer does not also require the use of fuel energy for it to work and hence will cut significantly on costs which are attributed to running diesel engines to ensure that water pumps are supplying the farm with water. This also doubles up as a score towards environmental conservation efforts since it does not emit harmful matter into the atmosphere.
Agriculture
Potassium polyacrylate has also proven its use in agricultural practices. A widespread practice that uses Potassium polyacrylate is hydraulic mulching. Here, crop germination is speeded up by mixing of water and seeds, along with other additives. This is especially done where there is no ample rainfall to enhance the germination and growth of plants (Al-Assam & Sattar, 2005). Moreover, when carrying out crop farming in an arid area where irrigation is boosted by the use of potassium polyacrylate, the land is normally accessible at all times since its fixing and working does not hamper or interfere with other farm operations such as thinning, pruning, weeding among others.
Besides, not only does potassium polyacrylate help in spreading water to plants especially around the root areas, but the polymer can also be used in spreading fertilizer and herbicides to the plants with minimal wastage being experienced (Al-Assam & Sattar, 2005). In such a case, the irrigation water is mixed with the fertilizer or herbicide and the irrigation process is then carried out normally. This will ensure that the fertilizer gets to the intended areas while helping to retain moisture content so that the fertilizer or herbicide does not concentrate and dry up in a single area (Liang & Zhan, 2007). Also of interest is its effect in controlling soil erosion as part of uses in agriculture. The structure of potassium polyacrylate is such that it will improve the soil structure ensuring that it is properly aerated, porous and keeps the soil particles together hence minimizing the effects of soil erosion (Ahmed, 1990).
Coal dewatering application
Potassium polyacrylate is also used for dewatering coal. Due to its capability to absorb more water, many times its weight, potassium polyacrylate when put together with wet coal will help to absorb the liquid (Geller, 2003). Since manual drying of the coal can take long periods especially in areas that do not receive sufficient sunlight, potassium polyacrylate can be used to sip water from the coal during any season of the year. This helps to reduce the duration of drying the coal as compared to when it is done under the sun. This, therefore, speeds up the coal preparation process before it is used to produce energy or heat (Peer & Venter, 2003).
Fire fighting
Due to the nature of the potassium polyacrylate which can absorb and hold water for longer durations, its application has found a way into the firefighting equipment (Al-Assam & Sattar, 2005). The material is used for layering fire helmets to be worn by firefighters when extinguishing the fire. This ensures that the inside of the fire helmet remains cool even when the outside temperature is very high due to the fire. This helps to keep firefighters safe from the high temperatures when carrying out their duties.
Waterproof tape and waterproof ointment
Potassium polyacrylate is also used in waterproof tapes especially lining for waterproof cables. Due to its ability to absorb water and release it back into the surface surrounding it, the polymer has proved its role in covering cables that are supposed to be waterproof (Ahmed, 1990). This mainly applies to cables that run on the surface, underwater, and also underground cables. The product is normally used to make close contact with the cables such that in case it comes into contact with the water, it will absorb it and release it back into the surrounding environment hence the cables will remain dry as intended.
Infant diapers and sanitary pads
Potassium polyacrylate has found wide application in the use of infant diapers and adult sanitary pads. This is due to its water or liquid absorbent nature and the ability to hold onto the water for longer durations before releasing it (Ahmed, 1990). This helps to keep infants dry since the baby diapers will absorb infant waste and keep it for long before the diapers are replaced. The same also applies to adult sanitary pads for ladies, which can absorb and retain liquids it comes into contact with.
Disposable mats for outside doorways
Potassium polyacrylate is also used as a component for making disposable mats used for outside doorways. Due to the mixed weather patterns of the outside doorways which experience both sunshine and rainfall, the polymer helps to keep the mats dry in wet conditions since it will absorb the water many times its self-weight. This makes the mats usable throughout since it will not budge with the weight of water but it will release it into the surrounding surface (Ahmed, 1990).
Comparison between traditional irrigation and irrigation using potassium polyacrylate
Irrigation methods have changed over time from the traditional methods to the current ones which ensure efficiency. This has come about mainly due to the increasing demand for water in the UAE due to the surging population numbers and also the high per capita water consumption being experienced in the region. Furthermore, the arid climate and the initiative to promote and boost agriculture have also contributed to the push for the innovation of better irrigation methods (Al-Assam & Sattar, 2005).
Initially, the UAE heavily relied on food imports to sustain its population which led to the high expenditure of foreign earnings (Shihab, 1996). This was not sustainable both in the short term and in the long run. This necessitated the need to have local food production boosted and thus the massive investment in agriculture and the incentives to support it. This has therefore facilitated the need to continue improving irrigation methods over time from the traditional ones to the contemporary ones (Mathew, 1987).
In trying to draw comparisons between traditional irrigation methods and the contemporary ones, the following aspects will be looked at to bring out the differences:
Water-saving
There is a significant difference when comparing traditional methods of irrigation to irrigation done using potassium polyacrylate in terms of the water consumed and saved in the process (Abedi-Koupai & Asadkazemi, 2006). Traditional irrigation methods such as basin irrigation are synonymous with water wastage and the irrigated plants end up receiving very little. This is even worsened by the harsh weather conditions which are mainly hot especially during summers where most of the irrigated water is lost through evaporation.
Potassium polyacrylate comes in handy when it comes to saving irrigation water. This is because the polymer can absorb water many times compared to its weight and can retain it for longer periods and only release it to the surrounding when it is needed. It has proven to be among the best methods of irrigation in arid regions and in terms of saving on irrigation water (Jain & Singh, 2010). By its nature, it will absorb a lot of water from the surrounding when supplied through irrigation or rainfall without wasting it through infiltration and evaporation to the atmosphere. With traditional methods such as basin irrigation, a lot of water will be released to the land, some of which freely spreads to areas where there are no plants hence leading to wastage (Al-Assam & Sattar, 2005). However, potassium polyacrylate normally supplies water to the root zones of the plant which ensures maximum utilization of the available water by the plants.
It can be concluded therefore that traditional irrigation methods did very little in terms of saving on irrigation water as compared to the use of potassium polyacrylate in the irrigation. This has helped in saving underground water channeled for agriculture purposes mainly for irrigation in the UAE (Brook & Achary, 2006). It is therefore a useful invention that has resulted in the boost of crop production in the region at large.
Reduction in the use of energy
The use of potassium polyacrylate has also resulted in massive reductions in the amount of energy consumed in carrying out irrigation (ACEEE, 2001). Traditional methods of irrigation saw the use of water pumps that required supplying a lot of water to the irrigation farms with increased frequency. Such pumps required electricity to run them or the use of diesel to propel the engines. However, the introduction and adoption of potassium polyacrylate have ensured that the water is retained for a long for utilization by the plants (Dawaoud & Abderrrahman, 2006). Also, it ensures that water is spread and used to the areas where it is required hence minimizing wastage that would have been experienced.
The constant supply of irrigation water to the plants through the use of potassium polyacrylate therefore means that the frequency of pumping water to the farms for irrigation has been reduced. This has cut down the expenditure that would have been incurred on electricity and diesel fuel to run the pumps (ACEEE, 2001). Water is thus not required to be constantly pumped to the farms at increased frequencies since potassium polyacrylate can absorb a lot of water once supplied, retain it for considerably long durations, and release it to the plants only when required (when there is a shortage of water in the surrounding environment). This has therefore reduced the amount of electricity that would have been used to run the water pumps and also the cost of fuel that would have been used to run diesel engine water pumps (ACEEE, 2001).
Increased crop productivity
Potassium polyacrylate has also contributed immensely to the significant increase in food production. This is mainly due to the reduced cost of irrigation as compared to the traditional methods where farmers would spend more to ensure that the plants are well irrigated due to the increased frequency of irrigation (Abedi-Koupai & Asadkazemi, 2006). With the use of potassium polyacrylate, there is a high yield with less use of the irrigation water due to its ability to absorb a lot of water, retain it for long periods, and only release it when required by the plants.
The irrigation process has thus become more efficient and reliable. Also, it has helped to reduce soil erosion hence conserving the soil as well. This is because the potassium polyacrylate forms an aggregate with the soil particles while making them porous and more permeable, more moisturized with improved soil structure. Besides, potassium polyacrylate can also be used to apply fertilizer and herbicides to the plants (Abd EI-Rehirn & Hegazy, 2004). This is done by mixing them with water and supplied through the normal irrigation process which has improved the uptake of fertilizer by plants as it does not go to waste. This has also helped to manage weeds in many farms as herbicides can also be applied via the irrigation method.
Environmental conservation
Environmental conservation has also come with the use of potassium polyacrylate for irrigation. First, this is because the polymer does not emit harmful substances into the surrounding atmosphere (Goldenberg & Reid, 1999). As part of its characteristics, it is non-toxic hence it does not pollute or harm what it comes into contact with. Secondly, since the use of potassium polyacrylate has cut down on the amount of diesel fuel that would have been spent to run the water pumps more frequently, it has, in the end, reducing the number of gas emissions into the atmosphere by also reducing the frequency to which water is pumped to the farms. This has helped in conserving the environment by reducing air pollution from gas emissions (Abd EI-Rehirn & Hegazy, 2004).
Statistics that relate to the application of Potassium Polyacrylate for agriculture benefits
Virtually all crops in the UAE normally thrive due to irrigation since the average annual rainfall is far way below what plants require for sustainability. There has been a significant boost in the agriculture sector, especially crop production due to the use of potassium polyacrylate. For instance, in the late 90s, the country was importing up to 70% of its food requirements. However, as time went on and the progressive use of potassium polyacrylate, more people got into agriculture which helped increase the level of food produced locally. This helped the government to significantly cut its expenditure on food imports due to the food being produced locally. For instance, poultry farming met about 70% of the requirements of eggs while also providing about 45% of the poultry meat required locally (Abedi-Koupai & Asadkazemi, 2006). Moreover, locally grown vegetables such as cabbage, tomatoes, squash, eggplant, and cauliflower have been able to meet the needs of the entire population. This helped to boost food security in the UAE.
The harvest from irrigated crops has also continued to improve in the UAE (Sawaf, 1980). For example, in 2003, 228,590 hectares were used for the irrigated crop area that produced 13% of green, 81% of palm trees, and 3.5% of vegetables The total production from irrigated crop areas in 2003 was comprised of 90 % coming from Abu Dhabi which has widely adopted the use of potassium polyacrylate which shows the significant role of the polymer in improving agriculture in the UAE.
Conclusion
In conclusion, there has been a significant reduction in irrigation water through the use of water-absorbing polymers in agriculture and particular sodium and potassium polyacrylate. Farmers applying potassium polyacrylate in irrigation have also saved considerably on the cost of electricity and fuel used for pumping the water to the farms (Jorgensen & Al-Tikiriti, 2003). This is because the polymer can absorb a lot of water and also retain it for longer periods thereby reducing the frequency of supplying water to the farms. The use of the polymer has also boosted agricultural production since it also helps to improve the soil it is applied to. It is therefore an efficient and effective method to be applied in irrigation.
With the UAE facing numerous water challenges mainly shortage, a lot has to be done to see that the population is supplied with sufficient water. Irrigation in the UAE has seen tremendous evolution from different methods that were time-consuming, expensive, and with little efficiency and effectiveness to the current methods. Since most of the irrigation water comes from underground which is under a threat of depletion due to continuous exploitation, more water-saving irrigation methods have to be adopted in agriculture and thus the shift to superabsorbent polymers, that is, potassium polyacrylate.
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