A Review Of Controlled Release Fertilizers Biology Essay

A Review Of Controlled Release Fertilizers Biology Essay In general, plants must be supplied with nutrients during the whole vegetation period. In horticulture this is achieved by applying quickly soluble fertilizer once to twice a week, for example. This kind of fertilizer application is very labour-intensive and requires considerable specialist knowledge, so as to select the correct rate of application, appropriate time of application and correct composition for the particular plants to ensure optimum plant production. With the use of slow or controlled release fertilizers the full amount of nutrients necessary for the whole vegetation period can be applied at the time of planting or at the earliest stages of plant growth, in the form of a nutrient pool Also, about half of the applied fertilizers, depending on the method of application and soil condition, is lost to the environment, which results in the contamination of water [1].This kind of environmental concerns of feeding crops with traditional fertilizers has led to developing Slow Release Fertilizers (SRFs) or Controlled Release Fertilizers (CRFs). SRFs or CRFs are easy and safe to use. They reduce risk of incorrect fertilizer application; they are labour saving; and minimize nutrient losses by leaching or fixation. The idea of producing SRFs was developed from 1963 by encapsulation of fertilizers by waxes. After that, these products have been commercialized. There are lots of SRF and CRF brands; market leader in controlled release fertilizers is Scotts Professional with key brands such as Osmocote Exact, Sierrablen and Osmoform. SunGro Company is also producing controlled release fertilizers with brand name of Multicoate. AGLUKON is also another commercialized SRF product [2-4]. Like lots of scientific fields, agriculture industry has been over shadowed by nanotechnology. Applications of nanotechnology in agriculture includes agriculture crop improvement, nanobiotechnology analysis of gene expression and regulation soil management, plant disease diagnostics, efficient pesticides and fertilizers, water management, bioprocessing, post harvest technology, monitoring the identity and quality of agricultural produce and precision agriculture[5]. Efficient pesticides and fertilizers in terms of Nano-composite based slow release fertilizers are developing in current decades. Using nanoparticles as reinforcing or cementing agent of polymer coatings has been the only feature of nano particles which is used in preparing slow release fertilizers [6,7]. Fertilizers Fertilizers are applied to soil to promote plant growth. They contain some beneficial nutrients including macronutrients and micronutrients. Macronutrients are nitrogen, phosphorus, and potassium which are added to soil in quantities from0.2% to 4.0% (on a dry matter weight basis) and are more essential than micronutrients. Micronutrients are elements which are applied to soil in much smaller amounts, ranging from 5 to 200 ppm, or less than 0.02% dry weigh. These elements could be sulfur (S), boron (B), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), zinc (Zn)[8,9]. 2.2. Types of fertilizers Fertilizers would be categorized from source of being and also from release properties points of view. All fertilizers could be organic or synthetic from source of being point of view. Organic fertilizers are naturally occurred including seaweed, worm casting, manure, slurry, peat, humic acid, guano and brassin. They provide slow release of nutrient as they need soils bacteria to be broken down to needed elements. Also, they may improve the biodiversity of soil by supplying organic matters and micronutrients for organisms. Organic fertilizers are cheaper and safer than synthetic fertilizers [9,10]. The main synthetic or mineral fertilizers are urea, ammonium sulphate, ammonium phosphate, phosphate rock, potassium chloride, super phosphates, calcium ammonium nitrate, potassium sulphate and NPK, PK and PK compound fertilizers. The most important drawbacks of synthetic fertilizer is their long term sustainability. Also, they are more expensive in contrast to organic fertilizers [10]. Also, fertilizers can be categorized into ordinary and controlled release fertilizers from release properties points of view. Drawbacks of non- controlled release fertilizers Ordinary fertilizers leach to soil very quickly and most of them are not used by the plants. According to figures about 40-70% of nitrogen, 80-90% of phosphorous, and 50-70% of the applied normal fertilizer is lost to environment and cannot be used by plants[11]. This rapid leaching will cause burning of plants and growing in spurts. Also, the lost elements will make some serious problems for our environment. Eutrophication, Blue baby syndrome, soil acidification, persistent organic pollutants, heavy metal accumulation, atmospheric effects are environmental concerns of ordinary fertilizers. Another result of quick leaching of fertilizer is repeating the application of fertilizers which will increase the costs[8,12,13]. Slow or controlled release fertilizers Slow release fertilizers or controlled release fertilizers are coated in a substance that enables a slow release time and eliminates need for constant fertilization and higher efficiency rate than soluble fertilizers [14]. The interest in these materials is for one or more of the following reasons: Availability of nutrients during the hole growing-season; reduced nutrient loss via leaching and run-off; reduced cost and labor outlay in crop production; reduced chemical and biological immobilization reactions in soil which cause plant unavailable forms; reduction of rapid nitrification and nitrogen loss through ammonia volatilization and denitrification; reduced seed or damage from high local concentrations of salts; reduced leaf burn from heavy rates of surface-applied fertilizers; better seasonal distribution of growth and better acclimatization in home or display environment; improved storage and handling of fertilizer materials[15]. Differences between slow and controlled release fertilizers Although there is no a special difference in general function of CRF and SRF, but it should be mentioned that they are manufactured by different materials and techniques with different properties. In slow release fertilizers elements are present in the fertilizers in a chemical form, which is not available to plants and they will be converted by physiochemical effects or microorganisms activities into nutrient forms in the soil. But in controlled release fertilizers elements are packed in coated granules and are released through the coating over a certain period of time. Also, in SRFs nutrients available period is affected by a lot of factors such as water content of soil, Ph, temperature, microorganisms activity, aeration. However, the longevity of CRF depends on coating thickness and temperature of soil. Only coating method is effective in changing pattern of nutrients release and a fixed coating thickness control nutrients release. In CRFs declared release time refers to soil temp erature of 20-21 oC. Higher temperatures accelerate the element release and lower temperatures make it longer [4,16]. SRFs are chemically prepared slow released. Some kinds of SRFs are Urea Aldehydes (UA) and Chelated Micronutrients(CM). Common type of UAs is urea formaldehyde which is high nitrogen fertilizer. Starting release rate of UAs is high but it dies off slowly for 3 years. This kind of fertilizer depends on microorganisms to break it down for plant use. CMs are substances that hold firmly together iron, manganese, zinc, and copper. They slowly releases over a long period of time [17]. 2.4.2. Types of CRFs 2.4.2.1. Sulfur Coated (SC) Elemental sulfur when is oxidized to its sulfate form would be one of the nutrients which is essential for some plants and is normally blended with other fertilizers. Using sulfur coating is also another way to provide sulfur simultaneously with making slow release properties for a core granular fertilizer. As the sulfur containing materials like polysulfides or lingosulfonate are brittle and also give a low wetting of defects they are normally mixed with waxes or plasticizers. Many formulas are available for SCs. Their release time is generally 3-4 months. SDs are released by microorganisms [18-22] 2.4.2.2. Wax coated (WC) One of the methods of reducing fertilizer release rate is dispersing granular fertilizers with molten wax and then cooling the mixture below the melting point of the wax [23]. Paraffin is one of the most used wax as a coating for fertilizers. Paraffin  wax   is a white, tasteless, odorless, waxy solid, with a typical melting point between about 47  °C and 64  °[24]. Other types of waxes are synthetic oil based, petroleum or mineral waxes. Waxes are normally used by an additive or a tackifiere agent to make a good sealing properties [25,26] 2.4.2.3. Polymer Coated (PC) Polymer-coated fertilizers (PCF) represent the most technically advanced controlled released fertilizers. They include a water-soluble fertilizer core and one or more than one layers of polymer. There are large varieties of polymers to coat the core fertilizer also the coatings layer could be the same one or different. In PC fertilizers release of nutrients will happen by diffusion through a semi permeable polymer membrane. Water penetrates the coating and dissolves the core. Release rate can be controlled by varying the composition and thickness of the coating. In addition, pressure builds up can cause cracks to form, from which fertilizer passes into the soil [27, 28]. 2.5. Review of preparation methods of different polymer coated CRFs 2.5.1. Sole Polymer coated One type of polymer coated CRFs is the one which the fertilizer core which could be N, P, K OR NPK compound, is just coated with one or more than one layer of polymer coating. In this case the polymer could be solvent based or water-based. The application process starts with dissolving the polymer in a organic solvent or water. After dissolving the coating will be sprayed onto the fertilizer in a coating drum or fluid bed [29]. Benefits of polymer coated CRFs are as follow; uniform and defect free coating will surround fertilizer; the coating will be very tough and durable which is resistant against mechanical breakdown; they are biologically inactive so they will not breakdown by soil microbes. In most cases except for degradable polymers release of fertilizers will be happen by diffusion through polymer coat rather than through defects. In some other coated fertilizers like sulfur coatings there should be a flaw in coating to make release of fertilizer. There are lots of examples for polymers which have been used in literatures as coating for fertilizers, some of them are as follow; dicyclopentadien[30],Urea and urethane based [31-36], epoxy based [ 37-39], polyvinylidene chloride-based latex[29] carboxyl-carrying ethylene polymers[40], biodegradable starch based[41], urea formaldehyde[42]. However, polymer coated fertilizers have some week points. About solvent-based coatings using large amount of organic solvents like toluene or xylene will lead to environmental concerns. These solvents are volatile and releasing them to environment makes some hazards for human health. Also, polymer coatings are more expensive than sulfur coatings; the process and equipments are also more complex than equipments used for other coatings. 2.5.2. Sulfur-polymer coated One of most common coated fertilizers are the ones in which core fertilizer is covered by a layer of sulfur coating and a layer of polymer. The polymer layer can be primer or outer layer; means that sulfur layer in some researches has been the first layer and in some others the outer layer. Sulfur Using coating is a suggested method to remove drawbacks of sulfur coated CRFs. One of these drawbacks is very fast release of fertilizer in first few days after application. The other one is brittleness of sulfur coatings which may lead to some fractures during handling or storage and losing the fertilizer into soil. Another problem is that sulfur coatings have a high surface tension with water and cannot provide enough wetting for a good diffusion [19, 29, 38, 21]. The most common method for applying the sulfur coating is spray. Molten sulfur compound will be sprayed over a pre-polymer coated fertilizer granule [38,43]. 2.5.3. Wax-polymer coated There are lots of researches focusing on making controlled release fertilizers using Wax-polymer coatings. Wax layer has three major benefits; one is that they are applied over the polymer layer for decreasing the fracture probability of coating and the other one is for decreasing the amount of polymer and avoiding consuming more polymers to make the process cost effective. Also, they can eliminate imperfection of granules surface to make a good surface coating. Most common waxes which have been used in state of the art is C30 alpha-olefin and paraffin. Other petroleum products like lubricants and bitumen or natural products like canola oil, soybean oil, coconut oil and palm oil, also have been used. After melting the wax it will be applied by mixing with polymer coated fertilizer. Normally the polymer is thermoset to avoid any damages of polymer by the wax in its melting point. The wax normally should have drop melting point from 50 to 120 °C. Wax is normally about 0.2% to 10 % by weight of fertilizer [25, 38, 44, 45]. 2.5.4. Filler- polymer coated As mentioned before, despite lots of advantages of polymer coating to make slow release properties when such polymers are used as a sole coating material the ultimate product would be expensive as you have to consume large amount of polymer. Using mineral or organic fillers is one way to avoid using large amount of polymer. Also, in some researches fillers play the role of detackifier, to prevent adherence of coated granules to each other, and strengthening agent [46]. Fillers may be used either as a mixture with polymer to make a nano-composite polymer [47] or as a separate layer. The most common method is second one in which the filler will be added and mixed with polymer coated granules before drying the granules. Most common used fillers are some very fine(less than 20 microns) inert inorganic materials like clay, diatomaceous earth, bentonite, kaolin, gypsum powdered limestone, talc, barium sulfate. Some other fillers like waste cellulosic materials also have used as filler in combination with polymer.[47-51] 2.6. Techniques coating application According to studies have been done; encapsulation methods of fertilizers can be divided into three methods including in-situ, spray and mixing. 2.6.1. In situ This method includes formation of fluid dispersion of the soluble fertilizer in a solvent and mixing the prepared solution with monomers of a polymer. Polymerization will happen and depend on the method; granules or particles of fertilizers will form. Ni et al [52] have developed a double-coated urea fertilizer. For preparation of poly (N-vinyl-pyrrolidone) hydrogels containing urea (PCU), the monomer and a solution of urea in N-vinyl-pyrrolidone were mixed together. The polymerization was carried out at 65à ¢- ¦C for 3 h. The resulting samples were vacuum-dried, milled, screened and stored. After that first coating was dried sample and some amounts of urea were mixed with sodium alginate (SA) solution. Mixed solution was then added drop wise into 5% (w/w) CaCl2 aqueous solution and stirred constantly. The drops immediately turned into granules (about 4mm in diameter) because the SA in the drop was crosslinked by Ca2+ at once. The granules were filtered and dried in oven at 70à ¢- ¦ C. Then the granules were added to ethylcellulose ethanol solution. Multiple EC coatings were prepared by immersion of the previously coated granules into the Ethylcellulose (EC) solution repeatedly. Thus, EC-coated urea granules with different coating thickness were obtained. Hanafi et al [53], have coated a compound fertilizer by polyvinyl chloride (PVC), polyacrylamide (PA), natural rubber (NR), and polylactic acid (PLA) using in situ method. For encapsulation of compound fertilizer with polyacrylamide the granules were added to the solution mixture of monomers. Then the polymerization reaction will start in existence of fertilizers. The thickness of the coating layer on the compound fertilizer granules, determined by SEM, gave PVC compound coated fertilizer the highest value of 3.04 lm, and the lowest was obtained by PA (2.04  µm). Variation in the characteristics of the polymers would be utilized in producing CR compound fertilizer that fit the requirements of growing plants. Hudson et al [38] used epoxy to coat the fertilizer. In this research the urea granules were charged to a pan and warmed to 95 °C. Then the hydrogenated tallaw amine, 2-amino ethyl peperazine and bisphenol A diglycidyl ether were mixed and were added to the granules; meanwhile polymerization happened and prepared mixture was agitated till the fertilizer granules dried. 2.6.2. Spray method This method is most common method for coating the fertilizer granules in state of the art[. Usually, the solution of polymer in a suitable solvent is sprayed on the granule of fertilizer and then the granules are dried to remove the solvent through evaporation. The treatment is repeated as often as necessary until the desired coating percentage is reached. Lan et al [54] have used Chitosan and poly(acrylic acid-co-acrylamide) as biodegradable polymers to coat the NPK fertilizer. The NPK was compound fertilizer granules with about 2 mm in diameter. It was placed in a rotary drum and then the Chitson powder which was dissolved in epoxy-aceton solution was sprayed over the fertilizer. After drying the coating , Chitson coated granules were added to a flask equipped with a mechanical mixer. Carbon tetracholoride, polyethylene glycoloctyl phenyl ether, sorbite anhydride monostearic acid ester, solution of acrylic acid acrylamide , N,N- methylenebisacrylamide and ammonium persulfate was slowly added to the flask. After mixing the coated granules were dried in oven. This product with good controlled-release and water-retention capacity, being degradable in soil and environment-friendly, could be especially useful in agricultural and horticultural applications. Tomaszewska et al [55] have used spray technique for encapsulation of fertilizers. In order to improve the properties of coatings, the granules of previously coated fertilizer (wet method) were sprayed with a polymer solution or pure solvent (N,N dimethylformamide). Concentration of the polymer in solutions used for spraying was in the range of 13-17 wt%. Measurements of thickness, porosity of prepared coatings and microphotographic observation of the coatings were taken. Ma et al [56] have developed a method for encapsulation of fertilizer with a self assembled coating. The fertilizer granules were heated in a rotary drum to 75 °C for 10 minutes. Then the self assembling amphiphilic molecules (N,N-bisaminoethyl eleostearate) were sprayed over the fertilizer. After 20 minutes aliphatic isocyanates were sprayed over fertilizer. This process was repeated once again. The fertilizer kept for drying in the 75 °C for 20 minutes. Dai et al [57], have developed a controlled release fertilizer using a water soluble resin as a coating. The granular compound fertilizer was coated in fluidized bed. Lan et al [58], prepared a double-coated slow-release NPK compound fertilizer with superabsorbent and water-retention properties (DSFSW), whose inner coating was chitosan (CTS), and the outer coating was crosslinked poly(acrylic acid)/diatomite-containing urea (PAADU). This prepared product not only has slow-release property but also could absorb a large amount of water and preserve the soil moisture at the same time. In addition, the outer coating (PAADU) could protect the inner coating (CTS) from mechanical damage. These were significant advantages over the normal slow release or controlled-release fertilizers, which generally have only a slow-release property. The results indicated that the DSFSW could be found an application in agriculture and horticulture, especially in drought-prone regions where the availability of water is insufficient. At first the outer coating containing urea diatomite (PAADU) was prepared. The NPK compound fertilizer granule was placed into a rotary drum, and the Chitosan powder was stuck on the granules by means of epoxy dissolved in acetone. The adhesive was applied by spraying at regular time intervals. The process was finished until compact and homogeneous coating formed on fertilizer granule. The coated granules were dried to a constant mass at room temperature for 6 h. Then the CTS-coated NPK compound fertilizer granules were obtained. CTS-coated NPK compound fertilizer granules were dipped in water and then were immediately placed on PAADU powder and shaken. In this manner, PAADU could adhere to the surface of CTS-coated NPK compound fertilizer and form the outer coating. The surface of the product was crosslinked by spraying methanol solution of epoxy chloropropane and then dried in a 70  °C oven to obtain the final product, i.e., the double-coated slow-release NPK compound fertilizer with superabsorbent and water-retention. Hansen et al [36], encapsulate the granular fertilizer with the epoxy resin using spray method. In this research not coated fertilizer was placed in a rotating drum and pre heated to 250 ° F. A rapid drying solution of copolymers dicyclopentadiene and a modified vegetable oil were applied over fertilizer using spray in a thin stream of resin. Simultaneously hot air was passed through drum. Next monomers of second resin including a mixture of epoxidized soybean oil and polyester curing agent were applied over prepared granules. The solvent was a mixture of xylol and Cellosolve acetate. Hansen et al [39] also have used the above mentioned method for encapsulation of fertilizer with polyurethane. First of all the preheated fertilizer was coated by a synthetic drying oil. After drying the coating for a few minutes fertilizer were dusted by clay. Then Urethane solution in xylene and Cellosolve acetate were applied using spray. 2.6.3.Simple mixing In this method granules are simply mixed with the coating at its melting point or with a solution of polymer in a suitable solvent. Tomaszewska et al [59] used this method for coating the granular NPK fertilizer with polysulfone (PSF), cellulose acetate (CA) and polyacrylonitrile (PAN). The coating solutions were prepared by the dissolution of the solid polymer in adequate solvent. The NPK fertilizer was successively added to adequate polymer solution, and was covered by a thin layer of the solution. Subsequently, granules were dropped into water, where the gelation process takes place. The coated granules were removed from the precipitation bath and then dried to a constant mass. The multiple coatings were prepared by immersion of the single coated fertilizer into adequate polymer solution, then into water and drying. Hon [47] has prepared the coated granules by mixing method. After melting the thermoplastic polymer by heating, the cellulosic additive has been added to melt resin. Then after allowing the temperature to drop, for avoiding the fertilizer damage, the granules or powder fertilizer has been mixed with the prepared mixture using a Brabender Mixer. Markusch et al[60] just has mixed the fertilizer pellets with at first, a diluted polyol and then with a diluted isocyantae to make a polyurethane coating. Then the feretilizer were placed in oven for drying. 2.7. Special equipment for application of polymer coating Typical physical method for encapsulating fertilizers are spray coating, spray drying, pan coating, rotary disk atomization. Special equipments for these methods are rotary drum, pan or ribbon or paddle mixer, fluidized. Fluidized bed and rotary drums are the most important equipments [87, 88] Polymers used as coating for CRFs A broad range of polymers has been used in fertilizer coating. These polymers could be thermoset, thermoplastic or biodegradable. Some of common thermoset polymers are urethane resin, epoxy resin, alkyd resin, unsaturated polyester resin, phenol resin, urea resin, melamine resin, phenol resin, silicon resin. Among them, urethane resin urethane is very common used.[36,61] Thermoplastic resins are not very common used in art because of some problems. As mentioned before a very preferable method of applying polymers is spraying the dissolved polymer over granules. Either some of thermoplastic resins are not soluble in a solvent or make a very viscose solution which is not suitable for spraying. Polyolefine is used in art for coating the fertilizer granules [47,62]. Biopolymers, dispose in bioactive environments, degrade by the enzymatic action of microorganisms such as bacteria, fungi, and algae and their polymer chains may also be broken down by non enzymatic processes such as chemical hydrolysis. Non-biodegradable polymers are not environmental friendly. Due to environmental concerns there are some trends of replacing non-bio with bio degradable polymers as coating material from 1970s. But it should be mentioned that they are expensive yet and not very cost effective. Also, in production process durability of polymer should be adjusted with release time of fertilizer. Among natural and synthetic biopolymers starch and cellulose based polymers, chitosan (a linear  polysaccharide),poly lactic acid and poly(ÃŽÂ µ-caprolactone) due to low cost and abundance are some of used biopolymers in fertilizer industry[41,52,58,63-69] 2.5. Coating thickness Generally, polymer coatings are applied in a thickness which is suitable to make a desired controlled release property. Thickness could be related to characteristic of polymer and also it depends on existed porosity of polymer surface. If water vapor transmission rate of coating material is 0.01 to 20, coating thickness would be 1 to 100 microns. Preferred coating thickness is 1 to 50 microns. Coating process could be repeated more than one layer to get desired nutrient release [49]. 2.6. Investigation of release behavior of CRFs Release mechanism for different coatings is different. Thick encapsulated granules like sulfur coating will allow the nutrient to release when a flaw or rupture appears on the coating surface. In this case, rupture will happen because of permeation of water into coating and inside osmotic pressure. Also, biodegradable polymers will release nutrients while destroying by soil microbes activity. Polymer coatings or combination of different coatings will happen by diffusion of water through walls porosities. In this case release rate of can be controlled by the particle size of coated granules, thickness of coating and permeability of coating surface. Also, altering the chemical composition of fertilizer core and the coating will change permeability of coating; means that even basic or acidic environment will change the permeability. In some researches when the coating has been starch-vinyl, increasing size of encapsulated granules has led to slowing down the nutrient release [70, 71]. There are some standard test methods for measurement of controlled release properties. According To European standard the standard release time of N during 24 h should be 15% of total core nutrient. Also, release rate for 15 day should be 75% of total nutrients. Also American and Japanese standards say that the initial release shouldnt be more than 40% of total nutrient. According to European standards for measuring the release rate encapsulated fertilizer should be immersed in pure water at 25  °C (room temperature) in incubated state [72, 73]. For example Detrick et all[43] have investigated the release behavior of their product by immersion of 20 g of encapsulated granules for 8 h in water. After filtration of solid they dried the solid. Evaporation of water was done at 100  °C for 8 hours. Also, Ma et all [31] placed 14 g of granules in wire mesh holder into a jar with 300 ml water at 23  °C and agitated ir by an orbital shaker. Then, the adequate water was taken for elemental analysis.. Locquenghien et al [40] for investigation the slow release effect of fertilizer some amounts of fertilizer were continuously extracted with water. For this purpose the granules were arranged in layer in a cylindrical vessel field with water. Water was passed through this layer and its Nitrogen content was analyzed. 2.8. Commercial CRFs in world and Malaysia Urea-formaldehydes are oldest slow release products which were produced in 1936 and then were commercialized in 1970s. These products were known as Ureaform, Bluchip, Nitroform Methex and Nutralene. After that Tennessee Valley introduced sulfur coated urea technology in1960s.Polymer coated fertilizers were produced as early as 1970 in Japan. Most important commercialized polymer coated CRFs are Osmocote, Nutricote [74] Osmocote CRFs are NPK granules coated by a thermoset copolymer of dicyclopentadiene and a glycerol ester (linseed oil) dissolved in an aliphatic hydrocarbon solvent. The Osmocote CRFs are normally used for ornamental horticulture production like greenhouses, nurseries , citrus , and strawberry production[75]. Nutricote prills are encapsulated by thermoplastic resins likeas polyolefins, polyvinylidene chloride. The process of Nuricote involves dissolving polymer in fast-drying chlorinated hydrocarbon solvents and then applying the solution to a variety of nutrient substrates including urea, potassium sulfate, diammonium phosphate, ammonium nitrate and potassium chloride. Blendin the polymer with talc and ethylene-vinyl acetate has been done to obtain desired release rate[76] Sierra, Lesco and polyon are some other commercialaized CRFs in the world. In Malaysia two brands named Greenfeed[77] and KAMILA[78] has developed slow release fertilizer. Greenfeed contains Zeolite which helps to release nutrients when it is in contact with soil. KAMILA is specially formulated for oil plantation industry. 2.9. Tracing nano-technology features in fertilizer industry Reviewing literature shows that researches which have used nano-technology features in fertilizer industry are very rare. The main benefits of nanoparticles in these researches are using them as reservoir of fertilizer or as filler [79,80]. Solid nano-particles, have large surface areas and their reactivity is much more greater than that of micrometer size materials. Also, their surfaces and interfaces provide an active substrate for physical, chemical, and biological reactions [80]. Two published researches have done using nano-particles. One has used nano-clay as carrier of metal-urea complex; urea intercalated clay without any coating has been developed as slow release fertilizer[79]. In other one, a nanocomposite of nano particle, fertilizer and polymer has been granulated and developed as slow release fertilizer. The production method involves mixing monomers, adding nano particle, which could be nano clay, nano bentonite, nano kaolin, polymerization and then granulating the mixture. In this research nano particle just work as good and effective filler [81]. Making polymer-nano-particle composites is something common in industries. Lots of researches have been done in this area, but researches around using nano-particle as reservoir for fertilizer have been done rarely. For more study here, we will review the researches have been done. 2.9.1. Interc

Teenagers of Today’s World Have a Better School Life Than Their Parents Had When They Were at School

I hear my father often saying to me that we, the children of the present age, enjoy more freedom than they did when they were children. I admit to myself, perhaps it is true. If we require anything, for personal use or for school purposes, our parents buy them without hesitation. They love to get us things we demand. Today, it is a very, very ordinary thing to find a school going teenager talking into a smart-looking cell phone, or browsing internet, looking for scholarships or other academic centre where s/he wants to go for studies in future. A growing child dresses well, goes out with her/his parents to swanky restaurants to dine, travels once or twice a year and has her/his birthdays celebrated ritually every year. Actually, these days, being the apples of the eyes of their parents, children will lack nothing that they can afford. All very well for the children of today. If we consider the above examples, some of us may agree that the children of our present day are indeed fortunate. But, consider the issue a little bit deeper. Are there actually roses, roses all the way for the growing children like us? Let us look around us, how the world is taking shape, how everything is changing. We can no longer be like the children of yester years, with a free mind and body, playing to our heart’s content, remaining childlike. With the exception of a few holidays every day in our life is bound to a regimental routine. We have to get up early in the morning, prepare ourselves for school, and come back in the afternoon. In the evening, it is homework time and time for the preparation for the umpteen examinations. In between the daily routine, we have to go to learn and acquire new skills, how to draw how to dance well and recite, how to compute like a professional and how to swim gracefully. Then there are more for others. Some go to learn playing tennis or chess, cricket or soccer, badminton or basketball. All this, we are taught, is for a successful life afterwards. We cannot hope to get admission in any reputed institute later on unless we score a certain percentage of marks in our board examination. Even after that, we have to appear for a tough merit test to acquire a seat in the institute. Our parents stake high hopes on us that we would bring luck in our family become someone to be proud of. Now, is it not a challenge we face everyday? A modern child has to face challenges everywhere. Security and love of the family cannot protect her from the competitive world. The on going onslaught of being left behind is always lurking. We always have to be up and get going. It is always study time. Would some one please explain why all work and no play makes Jack a dull boy?

Natural Disasters A Natural Disaster - 2721 Words

Throughout human history there have been many kinds of disasters. Many of these disasters have been mad-made, whether they be the fault of improper infrastructure, lack of maintenance, or just poor planning from the engineers. These types of disasters can usually occur frequently and we usually we put the blame on someone who will pay for the damages to those who were affected by the disaster. There is however another type of disaster that plagues man-kind, and is known as a natural disaster. Natural disasters are the ones that are caused by Mother Nature, such as earthquakes, tornadoes, and severe flooding. Each type of natural disaster brings with it, its own types of hazards and ways in which people can prepare for them. Many of these types of natural disasters are unpredictable, so planning and managing them has to be done ahead of time in order to prepare for the worst after the disaster is over. There are however, some natural disaster that we can see coming, and even then we a re sometimes caught off-guard with the damages they can bring to an area. This was the case with hurricane Katrina in 2005. The massive storm caused millions in damages and killed thousands of people, and was a lesson that sometimes we are not fully prepared to handle nature’s wrath. The lessons that we learned from hurricane Katrina are vital to help us prepare for another massive storm if it were to hit in the near future. Hurricane Katrina was a massive storm that was unlike any otherShow MoreRelatedNatural Disasters882 Words   |  4 Pages Natural disasters in Australia Natural disasters are events that occur naturally such as earthquakes, cyclones, Storms, and floods. These kinds of disasters can cause significant physical damage, interruption of business services and personal injury/loss of life. Due to the effects of global warming and consequential climate change the rate of natural disasters in Australia is increasing day by day. I myself have faced such kind of natural disaster in Pakistan in theRead MoreNatural Disaster2278 Words   |  10 Pages†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦..†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.8 Natural disasters introduction A natural disaster is the effect of a natural hazard (e.g., flood, tornado, hurricane, volcanic eruption, earthquake, heatwave, or landslide). It leads to financial, environmental or human losses. The resulting loss depends on the vulnerability of the affected population to resist the hazard, also called their resilience. This understanding is concentrated in the formulation: disasters occur when hazards meet vulnerability. A natural hazard will henceRead MoreNatural Disasters And A Christian God1538 Words   |  7 Pages Natural Disasters and a Christian God Over many centuries the world has experienced what we now call, natural disasters. We can define natural disasters as an extreme and sudden event caused by environmental factors that injure or kill many people and destroy mass amounts of property. Examples of natural disasters are earthquakes, hurricanes, floods, and disease. They can strike anywhere on Earth with or without warning. The severity of these disasters depend of the preparedness of the people andRead MoreNatural Disaster and Decision That Follows620 Words   |  3 PagesNatural Disaster and decision that follows Natural disaster risk can be defined as follows: The exposure or the chance of loss (of lives, persons injured, property damaged and economic activity disrupted) due to a particular hazard for a given area and reference period. In case of a disaster event, there are several effects, such as humanitarian effects, including the loss of lives and persons injured; ecological effects among other damage to ecosystems; and economic effects, comprising differentRead MoreEconomic Impacts of Natural Disasters1887 Words   |  8 PagesIMPACTS OF NATURAL DISASTERS ABSTRACT: Disasters of both natural and technological origin have a considerable impact on communities. The effects of disasters in India are significantly reduced by well established counter disaster arrangements at all three levels of government. These arrangements comprise comprehensive plans of prevention, preparedness, response and recovery and in more recent times, of mitigation. The economic effects of disasters can be devastating and widespread. When disasters strikeRead MorePost Natural Disaster : Transitional Shelters2889 Words   |  12 Pages Post-Natural Disaster: Transitional Shelters Alyssa Rupp University of Minnesota The obtainment of a safe shelter is placed alongside nourishment in a human’s basic survival requirements. It lands within the second layer of Maslow’s hierarchy of needs theory, following the most essential physiological layer (breathing, food, water, sleep etc.). 17% of the global population is without an acceptable shelter. Millions of people live in homes in desperate needRead MoreNatural Disasters And Attacks By Individuals Or Groups1710 Words   |  7 Pagesworlds history, there have been many natural disasters and attacks by individuals or groups, which have done extensive damage to cities, forests, and families within societies communities. The question that remains is, are there systems in place to effectively handle situations accordingly? In Canada, there is a model in place called the Incident Command System, (ICS). According to I.C., (2012), â€Å"An incident is an occurrence, either caused by humans or natural phenomena that requires a response toRead Mo reHow Are Natural Disasters Socially Constructed? Essay1333 Words   |  6 PagesWith reference to various examples, discuss how ‘natural’ disasters are socially constructed. While natural disasters such as floods, drought and hurricanes are commonly thought to occur due to environmental forces such as weather, climate and tectonic movements; a deeper investigation into the ‘disaster’ displays other contributing forces. Human factors have a large, if not equal, contribution to the occurrance and outcome of such disasters (Pelling, 2001). As Pelling (2001) argues, there isRead MoreResponding To A Man-Made Or A Natural Disaster Presents1443 Words   |  6 PagesResponding to a man-made or a natural disaster presents dangers and difficulties to first responders, and involved agencies, whether they are local, state or federal agencies. The difficulties in responding to these critical incidents make having a plan essential to successfully respond to, and manage the outcome of a critical incident. The United States government has established a national plan called the National Incident Management System (NIMS). NIMS is comprised of 6 components which helpRead MoreNatural Disasters And Public Health Of The Affected Communities2138 Words   |  9 PagesIntroduction Natural disasters will always cause damage to the infrastructures and public health of the affected communities. Low income countries are the most vulnerable because of a lack of preparation for coping with the displaced population. Displaced populations of vulnerable areas are often subjected to poor sanitation and hygiene practices and inaccessible clean water, both as effects of crowding and being in an unfamiliar environment. It is the primary cause of communicable diseases following

Bans, Laws, And Taxes On Smoking Essay - 1020 Words

Bans, Laws, and Taxes on smoking With the changing of times, many places over the years have gone smoke free. Some of these places include: hospitals, airplanes, restaurants, bars, universities, schools, hotels and many others. One of the places in Anchorage that has recently gone smoke free is the University of Anchorage Alaska. According to an article titled â€Å"History of Smoke and Tobacco-Free UAA† (n.d.), â€Å"With the new policy, UAA joins more than 1,500 colleges and universities in the U.S. that are smoke or tobacco free.† This policy was voted for and created by students to positively influence the health of students and faculty in the University System and to decrease the amount of secondhand smoke. According to an article titled â€Å"UAA Smoke and Tobacco-Free† (n.d.), â€Å"The new smoke and tobacco-free policy encourages health and safety and promotes a supportive environment that helps those who want to quit and prevents young people from smoking and using tobacco in the first place.† UAA officially became a smoke free campus November 17, 2015 during the Great American Smokeout, and has provided resources for quitting. Additionally, the U.S. Department of Health and Human Services (2014) states â€Å"Smokefree laws and policies have been proven to reduce the incidence of heart attacks and other coronary events among people younger than 65 years of age, and evidence suggests that there could be a relationship between such laws and policies and a reduction in cerebrovascularShow MoreRelatedThe Effects Of Secondhand Smoke On Public Places1548 Words   |  7 Pagessupported for an elongated period of time such as the one of smoking laws. Back in 1964 the first surgeon general’s report on the adverse effects of smoking was published (1). Only a year had passed since the reports was published when the first law was set in place, the (cigarette labeling and advertising act of 1965) was the first of many laws that would be passed over the last 60 years (1). By 1971 the surgeon general had proposed a federal ban in public places followed by a report in 1972 that talkedRead MoreTobacco And Its Effects On The United States1061 Words   |  5 Pagesfliers in packs of cigarettes. In 2001, The Government of India decided to ban the advertising of cigarettes. This ban was created to help the youth of India and hoped to reduce the amount of future smokers. The proposal of this restriction caused debates between the government, advertising companies, and tobacco manufacturers. The supporting and dismantling arguments for these ethical and commercial causes of the ban have enabled the government to make their final decision. The Government ofRead MoreSmoking In Public Places - The Smoking Ban Backlash Essay1723 Words   |  7 PagesSmoking Ban Backlash Walking down Boston’s Boylston Street at the late hours of the evening, the sidewalks are crowded with smokers taking their last hauls before entering the bars for a night of drinking. Due to the smoking ban in all public work areas that has been in effect since May of 2003, restaurant and bar patrons of Boston bear the cold winter season approaching, and reminisce about the old days where it was legal to enjoy a smoke with a cocktail at a bar. In May of 2003, BostonRead MoreCigarette Smoking Should Not Be Banned1528 Words   |  7 PagesShould cigarette smoking be banned for everyone in the United States? Why? Why not? Should those who chose their time smoking to relieve stress, personal enjoyment, or simply just because, have to lose their right to what makes them happy? Smoking tobacco products has been around for decades and in many different forms. Should personal rights be pushed aside to please those around us that disagree with the so called â€Å"disgusting habit†? In the paper The Washington Times an article caught my interestRead MoreThe Externalities of Smoking1470 Words   |  6 PagesIntroduction In the past decades, an increasing number of countries have imposed a ban on smoking in public places, including restaurants and bars. Unlike other regulations of cigarettes such as tax or promoting ban, this territorial smoking control sparked heated debates. While some argue that the implementation of this regulation is inefficient and reduce the public welfare (Viscusi, 1994; Tollison and Wagner, 1992; Lambert, 2006), others claim that smokers do impose negative externalities toRead MoreSmoking Is The Single Most Preventable Cause, Disease, And Expensive Medical Expenses856 Words   |  4 PagesIn most cases, smoking is ongoing. Smoking have led to deaths and diseases within individuals. There are issues with the increased medical expense that are associated to smoking. Cigarette companies are gearing their advertisements towards the younger generation to reel in first-hand smokers. Tobacco industries have a large amount of money so they can afford lobbyists to do their biddings and secure their agenda. Furthermore, smokers know how hard it is to lie down their packs of cigarettes and quickRead MoreThe Main Influence Of Government And The Idea Of Democracy1530 Words   |  7 Pagesmany issues today have occurred that weren’t relevant in the past. In this essay, the three main topics that will be addressed are laws to improve workplace health, laws to ban smoking in public places, and efforts to restrict voting rights. First, laws are made up by people to enact certain policies and ensure the safety of common people. There are some laws that are designed to protect the working environment for the employees from the danger of hazardous chemicals or inhumane regulationsRead MoreFree to Choose, Free to Kill? Analyzing the Smoking Habit in USA1727 Words   |  7 PagesFree to choose. Free to kill? Ah, smoking in America. After all these years, I still dont seem to understand how and why smoking is legal in public. Its an issue people love to talk about but never want to see a change in. I dont think it is possible that people dont know of passive smoking, which couldve been an explanation for their behavior, but since thats not possible, lets just say theyre freedom fighters for a lost cause. And whats the cause? Their fight to continue being allowedRead MoreEffects Of Smoking Ban On Children1747 Words   |  7 Pages Smoking Ban Name: Institution: Course: Date: The number of people suffering from secondhand smoke in UK and US has increased tremendously over the years. A lot of money which could have been used to start projects that will spearhead growth of the economy is being directed to treat these diseases. Majority of the affected population are young children. However, research has indicated that the largest number of these children emanates from family where none of the parent is a smokerRead MoreThe War on Tobacco1539 Words   |  7 PagesAccording to No Expectations for Cigars, the 2009 Federal Law that required the U.S. Food and Drug Administration to begin regulating, and how the law would regulate tobacco ;for example, ban free giveaways of any non-tobacco items with the purchase of a tobacco product or in exchange for coupons or proof of purchase (What FDA Regulation of Tobacco Products Really Means 3). Increasing taxes on cigarettes is an effective way to reduce teen smoking (Kline 139). The first viewpoint is all about regul ating