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Testing For Natural Herbicide, Eliminating The Weeds Fabian Ho Kai Bin(Leader) , Benson Quah , Myra Koh, Amelia Jane Lim and Lee Hui xin Pasir Ris secondary school The purpose of this experiment is about finding out the best householdchemical that can act as a good herbicide. Household item is tested is to prevent useof artificial herbicides, 2-4,d. Herbicide is substance that has 2,4-Dichlorophenoxyacetic acid which is used to kill unwanted plants but research hasshown that one of the most widely used herbicides, Atrazine, which contain 2,4-d,has been linked to cancers in humans, and sexual deformities in frogs so chemicalsthat are used are a combination of household and convenience item as they are lessharmful to the environment as compared to artificial herbicides. The materials usedare household item like distilled white vinegar, citrus oil, salt solution, coke, lime,rootbeer, clove oil, half-boiled egg, boiled water, tap water, soap, toothpaste, bleach,juglans which is commonly known as walnut and corn gluten meal which is alsoknown as cornflakes. Tap water is used for as the control for this experiment. Theother measuring materials are 100 milliliters of measuring cylinder, 200 millilitersof beaker, filter funnel, filter paper, soil, electronic balance, universal indicator,lighter, styrofoam cups and the weeds, Phyllantus Urinaria L. The hypothesis madeis that coke is the best household item that can act as herbicides while the othersubstance that can act as herbicides are distilled white vinegar, clove oil and lime.For alkali, soap and toothpaste are the one thought to be acting as herbicides. Asalkaline stuff had not been proven as herbicides, this became one of the aims of thisexperiment. When the clove oil was substituted as the herbicide, the weeds used tookno longer than 30 minutes for it to fully become discolored, before dying. This sameresult occurred for other similar tests conducted on the clove oil. Several factorshad been taken into consideration, such as cost, eco-friendliness and the speedwhich the plant is killed. While bleach, half boiled egg, clove oil, citrus oil, saltsolution and toothpaste can all kill weeds, the item that is concluded as the bestherbicide is the clove oil. The purpose of this experiment is has shown that one of the most widelyabout finding out the best household used herbicides, Atrazine, which containchemical that can act as a good 2,4-d, has been linked to cancers inherbicide. The reasons for the purpose humans, and sexual deformities in frogsare as listed. Firstly, household items are so chemicals that are used are atested is because it is inexpensive, combination of household andcommonly found and it also serve as an convenience item as they are lessalternative for artificial herbicides. harmful to the environment as comparedSecondly, household item is tested is to to artificial herbicides. Thirdly,prevent use of artificial herbicides, 2-4,d. preventing the use of “ugly” herbicides.Herbicide is substance that has 2,4- Glyphosate, the ingredient in Roundup,Dichlorophenoxyacetic acid which is is toxic to amphibians. Glyphosate isused to kill unwanted plants but research safe for use near mammals, but there is
some debate as to whether it is an contaminated with the Monsantoendocrine disruptor. Monsanto genetically modified canola blown in byCorporation, makers of roundup, created the wind. According to the Monsantoa genetically modified canola. The patent, farmers who use their canolamodified canola is resistant to roundup, seed must buy it every year. They cannotmaking it easier to treat weeds. This store seed. The chemical will be testedgenetically modified canola can cross on a weed named Phyllanthus Urinariapollinate with weeds, making them L, also known as Meniran. Phyllanthusresistant to roundup. No one knows the Urinaria L is a kind of weeds that haspossible effects of genetically modified small alternate leaves resembling thosefood crops intermingling with native of the mimosa tree, disposed in twoplants. As well, Monsanto sued a ranges. The leaves are large at the tipCanadian farmer whose canola field was and smaller towards the petiole. Material and Methods vinegar is 2.86, citrus oil is 4.36, salt The materials used are household solution is 7.00, coke is 2.54, lime isitem like distilled white vinegar, citrus 2.66, rootbeer is 4.75, clove oil is 6.12,oil, salt solution, coke, lime, rootbeer, half-boiled egg is 7.90, boiled water isclove oil, half-boiled egg, boiled water, 7.00, tap water is also 7.00, soap is 6.74,tap water, soap, toothpaste, bleach, toothpaste solution is 6.84, bleachjuglans which is commonly known as solution is 9.76, walnut is 6.31 in iswalnut and corn gluten meal which is powdery form, diluting with water andalso known as cornflakes. Tap water is cornflakes is 5.55 in its powder formused for as the control for this after diluting with water.experiment. The other measuringmaterials are 100 milliliters of The pH-value of the soap,measuring cylinder, 200 milliliters of toothpaste and the half-boiled egg willbeaker, filter funnel, filter paper, soil, be discussed later. The method used iselectronic balance, universal indicator, applying the household item to thelighter, styrofoam cups and the weeds, weeds after putting the weeds in cups.Phyllantus Urinaria L. This means that five grams of the respective chemical will be poured into The materials that are acidic are the cup that is labelled with the chemicaldistilled white vinegar, citrus oil, clove name.oil, walnut, coke, lime, rootbeer,cornflakes. The materials that are alkali The procedure for the experimentare soap, toothpaste and soap. Salt, goes. Firstly, hypothesis is createdboiled water and tap water are neutral before anything is done to have a roughsubstance. Most of the substances are idea of what the result of the experimenteither in powdery form, diluting it with would be like. The hypothesis made iswater or it is a solution. that coke is the best household item that can act as herbicides while the other The pH-value of the items listed substance that can act as herbicides areis also tested and the values respectively distilled white vinegar, clove oil andare as listed below. Distilled white Lime. For alkali, soap and toothpaste are
the one thought to be acting as weeds could photosynthesise thus lightherbicides. As alkaline stuff had not is not the factor why the weeds died.been proven as herbicides, this becameone of the aims of this experiment. Fifthly, the weeds are watered atSecondly, one hundred gram of mixed a frequency of two days as the weedsburnt soil is poured into cups of 15. This need it to stay alive also making sureis to ensure that the amount of soil is the water is not one of the factor why thesame to ensure that the experiment weeds dead. Observations of the weedwould not be affected thus having a fair are recorded before and after the threetest is needed. days as to see the differences thus having a clear eye of the changes. Last Thirdly, one Household chemical but not least, the results are recorded onis pour into each cup with each cup a small booklet to have a reference of thehaving the same amount of chemical. result. As to minimise the experimentalThis ensures that the experiment would errors that is made, the experiment isbe a fair one. Fourthly, the cups are left repeated for four times using the samefor three days facing the window at the procedures repeatedly, taking thescience lab. This is to make sure the average results in the end of the experiment.substances Initial length End length of pH of Did the plant of weeds weeds soil(acidic die? /alkaline)Half boiled 5.0 cm 4.5 cm 7.90 NoeggClove oil 5.7 cm 4.9 cm 6.12 YesCitrus oil 5.5 cm 6.5 cm 4.36 YesCornflakes 6.5 cm 4.9 cm 5.55 NoWalnuts 5.5 cm 5.7 cm 6.31 NoToothpaste 5.1 cm 6.1 cm 6.84 Yeslime 4.9 cm 3.2 cm 2.66 NoCoke 4.9 cm 4.9 cm 2.54 NoBoiled water 6.2 cm 6.7 cm 7.00 NoTap water 5.5 cm 3.9 cm 7.00 NoSalt solution 4.5 cm 5.0 cm 7.00 YesBleach 4.5 cm 5.6 cm 9.76 YesRootbeer 4.9 cm 3.2 cm 4.75 NoDistilled 5.2 cm 5.5 cm 2.86 YesWhiteVinegarLemon 4.5 cm 4.7 cm 6.74 Yesflavored soap Table 1
Results at the end of the experiment .Lime,This table is formed from the average acting as herbicide, killed the weed onceresult of all the experiment done. The out of three experiment, thus it may notresults collected have shown that there prove to be an effective herbicide. Whenare some convenience items that can also soap acted as herbicide, the weed wasbe used as effective herbicides, such as killed in every experiment, thus it issalt and toothpaste. It also shows that proving to be a quite effective herbicide.some items have positive effects on the The cornflake did not proved to be agrowth of the plant. All of the good herbicide. Through all thecarbonated drinks used in this experiments, the cornflake succeeded inexperiment aid the growth of plant , also kill one weed.cornflakes and walnuts are also agentsthat promotes growth of the plant. With This table also shows that thehalf boiled egg as the herbicide, the weeds might have grown by a littleweed died once out of three experiments before it is dead.and mould can also be seen growing onthe egg. The clove oil kills the weed In conclusion, research shownquickly and the weed that died leaves of that acidic substance like lime, walnuta deep brown colour. and cornflakes is not as effective as alkaline substance like toothpaste, soap The rootbeer does not kill the and bleach. So this research shown thatweed but instead it helps it to grow not all acidic substance is herbicides.better, at the end of the experiment, the The table shows that Clove oil, Citrusweed did not wilt but remain healthy. oil, Toothpaste, Salt Solution, Bleach,The salt solution did kill the weed. The Distilled white vinegar and Lemonweed has wilt and dehydrated .Also flavored soap are substance that killedsome of its leaves fell off. The bleach the weeds.effectively killed the weed which wiltsquickly but also the bleach increase the DiscussionpH value of the soil by an undesirableamount. The toothpaste killed the weeds After conducting the experimenttwice out of three experiments, the weed for four weeks, the results observed canwilt at the end of two experiments. be categorized into 2 different groups, namely weeds that die after 3 days, The vinegar changed the pH weeds that are still surviving and havevalue of the soil, making it more acidic, grown. However through the variousthus creating an unfavorable experiments, certain trends observedenvironment for the germination of remain constant.plant. The weed that was applied vinegardied. The weed that was applied with When the clove oil wascoke grew well and did not die at any of substituted as the Herbicide, the weedsthe experiment. The same can be said of used took no longer than 30 minutes forthe weed that was applied with it to fully become discolored, beforecornflake. The citrus is proving to be an dying. This same result occurred foreffective herbicide, it kill the weed in other similar tests conducted on theevery experiment. The weed always wilt clove oil.
most likely the cause of the wilted look Juglans nigra, more commonly and discoloration.known as walnuts have also displayedtrends that remained constant through When coke, root beer, lime, wasthe tests conducted. The walnuts when added, the leaves remained green withgrounded and applied on the soil shows some discoloration at the edges as itno change at first, but 3 days later, a grew to an average of 10cm. it is mostlayer of mold and fungi can be observed likely due to the nutrients added fromat the top of this layer of juglan the drink to the soil that the plant needs.herbicide. This phenomenon is similar to As the coke and root beer are boththat of the cornflakes although the consumer items, it could have containedcornflakes promote the growth of weed more amounts of nutrients as comparedrather than stunning its growth. to the level of acidity, hence caused more growth rather than elimination of The tooth paste and soap when the weeds.applied on the plant caused it to wiltdownwards presumably due to the As water, (control) and boiledweight. The same reaction happened to water was substituted as herbicides, nothe plant poured with bleach. However, visible signs of elimination happened,in both cases, it is once again possible but rather it grew to an average offor the 2 substances to raise the PH value 9-10cm. the most likely reason is due toof the soil to an alkalinity that the weeds the fact that water has proven to be aare not able to survive in, causing it to necessary essential, and that the plantwilt before dying. would not survive without it. The half boiled egg and citrus The agent can be split into twooil, although killed the weed several groups, the one that promote growth ordays later had also attracted an the one that stunt growth. In betweenincreasingly large amount of pests, these two groups, it can be split intohence is advisable to either use it with smaller groups to further understandpesticide or avoid using it. what is common in the ingredient that causing the chemical to fell into the The salt and white distilled category after research and comparison.vinegar also caused the weed to wilt andturn brown. This could be because of the Firstly, the one that promotesdehydrating agents found in both growth. Nitrogen (N) , phosphorus (P) ,substances. Because water is a very vital potassium (K) , calcium (Ca) ,component of what the weed needs to magnesium (Mg) , sulphur (S) , boronsurvive, without it, the plant would wilt. (B) , copper (Cu) , iron (Fe) , chlorideAs there is a higher concentration of (Cl) , manganese (Mn) , molybdenumwater present in the cell as compared to (Mo) and zinc (Zn) are the nutrientsthe soil contents added the salt or found in soil needed for a plant to growvinegar herbicide substitute, water from well. But firstly, it must be noted that thethe plant cells are lost through osmosis, 13 nutrients which come from the soil,causing the plant cell to dehydrate and are dissolved in water, and absorbedtherefore become flaccid. Hence, it is through the roots. However, there are
mostly insufficient amounts of thesenutrients. This is also the reason why Other chemical such as lime which alsomost farmers and gardeners use has acidic properties is instead used infertilizers to add nutrients to the soil. maintaining the soil’s PH value. When a soil has too much acidity, maybe due to The mineral nutrients can be fertilizers, irrigation of acidic water ordivided into 2 groups, macronutrients decomposition of soil organic matter,and micronutrients. liming is a common garden term to reduce the PH value of the soil. It is Macronutrients can then be necessary as nutrients, needed by plantsfurther subdivided into 2 more groups, to grow well lessens as the PH value ofknown as primary and secondary the soil drops below 6.0 on the PH scale.nutrients. The primary nutrients, Some of these nutrients include nitrogen,consisting of nitrogen, phosphorus and phosphorus, potassium, sulphur,potassium, are major nutrients that lack calcium, magnesium and molybdenum.the first as large amounts of it is used by As the amount of these nutrientsplants for survival and growth. decrease, the plant will be affected in terms of its colour, vigour, and ability to The secondary nutrients, resist and recover from heat, drought andconsisting of calcium, magnesium and traffic stress. By adding lime to increasesulphur, are much more abundant as the PH value above 6.0, the amount ofcompared to the primary nutrients. these nutrients is also, in turn, increased.Because it can replenish itself through However do note that an excessivenatural and non harmful ways, it is not amount of lime can cause high alkalinenecessary to add fertilizers. Through PH in the soil. If the soil PH exceeds 8.0,liming, calcium and magnesium are important nutrients such as nitrogen,largely produced. Sulphur is produced phosphorus, iron, manganese, boron,during the slow decomposition of soil copper and zinc becomes lesser,organic matter. resulting in an unhealthy less vigorous plant. Micronutrients are the elementsessential to a plants growth although it is In addition, by just looking at theonly used in small quantities as its name components in a raw lime juice, traces of(micro) suggests. The remainder of the calcium (14mg) , copper (0.027mg) ,nutrients fell under this category. It is iron (0.09mg) , manganese (0.018mg) ,also produced by recycling grass magnesium (8mg) , phosphorus (14mg) ,clippings or tree leaves. potassium (0.1mg) and zinc (0.08mg) which is needed for plants to grow canFrom the previous statement, it can be be found.concluded that not all acids are able tokill weeds such as coke and rootbeer. 11 According to researches, watergrams of phosphoric acid, And 30 grams has proven to be a necessary need forof lime juice can be found on the plants to survive, let alone grow. Asingredients used to make coke. Modern water acts as a solvent for minerals androotbeer has also shown common food, as it cannot be absorbed by thecomponents as coke. plant in a solid form. Another reason is
that the Water is used to transport the hydroxide creating soap and glycerol.metabolic products from one part to the For bleach, chlorine gas is passed intoother where they are needed. Thirdly, for sodium hydroxide for the bleaching ofthe plant to photosynthesize, water is clothing. As for toothpaste, sodiumone of the raw materials that are needed. hydroxide is use as a tooth whiteningAnd water lost through the stomata agent.through transpiration actually helps tocool the plant, in a similar way that Soap itself is a good herbicide because ithumans do through perspiration. This will destroy the weeds surface whichevaporation process also helps the will not allow the plant to photosynthesisstomata to remain open for the intake of and thus killing it. It also helps to controlcarbon dioxide. Finally, water also helps weeds due to the potassium salt of fattythe plant cells to remain turgid rather acidthan flaccid, resulting in a healthy From the research, it says thatupright plant look rather than a wilted fluometuron; an aryl fluoride herbicidelook. is use to kill weeds in grain and cotton fields. Therefore, it is inferable that Cornflakes on the other hand fluoride which is found in toothpaste canhave been known to contain iron, also be named as a weed killer. As foranother essential mineral that plants bleach, due to it being highly alkaline itrequire to grow. will detoriate the soil condition and thus resulting in the death of the weeds. In conclusion to thesecomparisons, it is possible to conclude From an article, it says that using ofthat water is the most important factor bleach as an herbicide is not a good idea.for a plant’s growth but lime actually It is sodium hypochlorite and that its pHprovides the plant with the most is 11.When bleach is added, it willnutrients it requires to grow. increase the pH value of the soil on the PH scale, and add sodium in to the soilHowever, anti-growth means that it does through the run-offs. In fact, it will benot provide growth for the weed thus providing an undesirable condition formaking it a good herbicide. The plant to germinate.following groups are those that are anti-growth- Soap, bleach and toothpaste, Also another common ingredient foundvinegar and salt, half-boiled egg and in soap, bleach and toothpaste is sodiumwalnut, lastly, clove oil and citrus oil. lauryl sulphate which is able to kill weeds. In most commercial herbicide,For soap, bleach and toothpaste, they all this is usually one of the activecontain a common ingredient of sodium ingredients used.hydroxide also known as caustic soda orlye. Sodium hydroxide is a register Salt and vinegar are also commonly seenherbicide which helps to control tree as a cheap and abundant herbicide inroots in sewage system which in turn households. As commercial vinegarwill kill the plant. Preparation of soap contains about 5% acidity, the acidthrough a process called saponification, present there affects the weed growth.where fatty acid reacts with sodium The acetic acid, found in vinegar, is not
absorbed into root systems, hence Next for the group of clove oil and citrusvinegar will eliminate surface growth, oil, they are both known as essential oil.but perennial plants (plants that live for For clove oil, it contains eugenol whichmore than two years) will reshoot. Note is a type of biocide. It is also a type ofthough, that commercial vinegar does phenol which is found in citrus oil too.not exceed 5% acidity whereas vinegars Therefore, the similar substance issold as herbicides have at least 10% phenol.acidity.The disadvantage of having vinegar as Clove oil kills weed by desiccating theherbicide is that vinegar can indirectly plant shoot, also from a research it stateskill the plants that are desirable. It is also that since it does not move into perennialnot a hundred percent control over the weeds, none of the substances willweeds. directly kill the root system. Another source says that due to the presence ofOne of the reasons why salt is used as an eugenol it will kill weeds by disruptingherbicide is due to the fact that the cells cell membranes and thus causing contentof plants contain a certain amount of like electrolyte to leak out resulting inwater and other dissolved substances. the cell death.When surrounded by water that contains As for the citrus oil, in most organica larger amount of salt, there is a general based herbicide there will be a certainrule, called osmosis, which water will try concentration of citrus oil being added toto move through the plasma membrane it. An example is the combination ofto make the concentration of dissolved vinegar and citrus oil. As this productsubstances equal. Hence, if there is a tends to be foliar spray which kills mosthigher concentration of salt outside the broad leaf weed on contact and manycell, water from the cell is lost to its other well established weeds that maysurroundings through osmosis. This need a stronger formula like thesame theory applies to how salt can be combination of vinegar and citrus oil.substituted as an herbicide. Lastly, it is the group of walnut.Another reason can be due to A black walnut produce a substancedehydration. Salt, applied to the ground called juglone (5 hydroxy-1, 4-around the weed will soak in and the salt napthoquinone). Juglone kills andwill interact with the roots. Water will be reduces plant growth like those founddrawn out to equalize the osmotic under the tree canopies. Juglone is also apressure, and the plants will die of toxin, which exerts its effect bydehydration. inhibiting certain enzymes needed for metabolic function. In a research article,However, the disadvantage is that it can it says that plants growing near the blackremain in the soil as run-offs and affect walnut tree exhibits systems such asdistant plant. It also affects the growth of foliar yellowing, wilting and eventuallydesirable plant other than the weeds that death. Juglone is present in all parts ofshould be eliminated. Salt also defeats the plant.the purpose of developing a healthy soil. The experiment for the walnut generally did not succeed was probably
due to the fact that the walnut used was for our experiment, it resulted in baked. But in researches it is the black substituting baked walnuts as the walnut and not baked walnut. Being herbicide instead. unsure of the species of walnuts used and due to unavailability of the species Plants Sensitive to Juglone Plants Tolerant of JugloneVegetables: cabbage, eggplant, pepper, potato, Vegetables: lima beans; snap beans; beets;tomato corn; onions; parsnipsFruits: apple, blackberry, blueberry Fruits: cherry; black raspberryLandscape plants: black alder (Alnus); azalea; Landscape plants: red cedar; crabapple*;basswood; white birches; Hopa crabapple*; elm; winged euonymus; forsythia;hackberry; Amur honeysuckle; Japanese larch; hawthorn; hemlock; hickories; blacklespedeza; lilac; saucer magnolia; silver maple; locust; most maples; oaks; autumn olive;mountain laurel; loblolly pine; red pine; scotch pachysandra; pawpaw; persimmon; wildpine; white pine; potentilla; privet; rhododendron; rose; sycamore; most viburnums; VirginiaNorway spruce creeper Flowers & herbaceous plants: bluebells; Kentucky bluegrass; daffodil; daylily;Flowers & herbaceous plants: autumn crocus ferns; fescue; iris; Jack-in-the-pulpit;(Colchichum); peony liriope; narcissus; phlox; poison ivy; Shasta daisy; trillium Field crops: white clover; red top grass;Field crops: alfalfa; crimson clover; tobacco orchard grass; soybean; timothy; wheat Table 2 Water is crucial to all lives, including the plant. If there is not enough entry of The third experiment was water in a plant, the plant could not get counted as a failure because no results of the nutrients it needs to survive. Water the weeds growth can be extracted and helps a plant by transporting important all weeds have died. It is believed that nutrients through the plant. Nutrients are the lack of water was the essential cause drawn from the soil and used by the for the plant to die because all the plants plant. Without enough water in the cells, that are used for this experiment, even the plants wilt, so water helps a plant the plant used as a control had died. stand. Water carries the dissolved sugar Another reason why lack of water was and other nutrients through the plant. So regarded as the essential reason for the without the proper balance of water, the plants is due to the fact that the fourth plant not only is malnourished, but it is experiment, which was carried out after also physically weak and cannot support the third experiment was a success when its own weight. the plants were watered, even though the other variables from the third experiment Photosynthesis is the process by which was left unchanged to the fourth green plants, in the presence of experiment. chlorophyll and light energy, manufacture carbohydrates (glucose) from carbon dioxide and water. While
carbon dioxide is considered essential the half boiled egg thus creating anotherfor this process, water is also counted as problem, to clean up the fungi. Thecritical raw materials that are needed for vinegar changed the pH of the soil thusphotosynthesis. Without photosynthesis, killing the weed, but it may also affectplants will die. surrounding wanted plants. The soap effectiveness as an herbicide is not asHence, from the third experiment, we good as clove oil. Thus, the conclusioncan conclude that other than the different that has been arrived is that clove oil,agents (vinegar, salt solution, distilled among all the other tested householdwater, etc.) that are used to test the best item is the best herbicide. This has to beherbicide; water is also an important further research and proven to confirmagent that affects the growth of the the results.plants. Particularly for this experiment,lack of water is believed to be the main Acknowledgementscause for the plants to die and water isproved to be an important agent in order We are thankful to Mdm Mok forfor the plants to survive. helping us in the experiment. We are also grateful to Mr.Kelvin Chee and While bleach, half boiled egg, Ms.Jasmine Goh in helping us in thisclove oil, citrus oil, salt solution and report and relevant matters in thetoothpaste can all kill weeds, the item experiment.that is concluded as the best herbicide isthe clove oil. Several factors had beentaken into consideration, such as cost,eco-friendliness and the speed which theplant is killed. Clove oil is massmanufactured; also, it can be easilybought from most shops. While salt canalso be an effective herbicide, the timetaken for salt to kill the plant is muchlonger than clove oil’s. In comparison toclove oil, the time taken for toothpaste tokill the weed is much longer. Citrus oilmay be another option as the bestherbicide but due to the cost, and also, itwill attracts ants and other pest and thusworsen the situation of the numbers ofunwanted pest present. Bleach is alsoanother very effective herbicide, but as itis harmful human being and also it willharm the environment and affect otherplants or crops by increasing the pHvalue of the soil, and thus creating anundesirable environment for any plantgermination. Half boiled egg also can actas herbicides, but fungus will grow on
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20 Learn how they work, and how to 24 Herbi-Systems. Frequent Asked use them effectively Questions. http://www.herbi- by Ann Lovejoy systems.com/FAQ_s/faq_s.htm http://encyclopedia.stateuniversity.com (accessed June 20, 2009) /pages/9965/herbicide.html Herbicide - History, Health effects, 25 Herbi-Systems. Weed facts. 29 http://www.freepatentsonline.com/ http://www.herbi- 6756341.html (accessed June 19th, systems.com/Weed_Facts/weed_fact 2009) s.html (accessed June 20, 2009) Mark. Czarnota. University of Georgia 26 Wim, Vermaas. (1998, March). 30 http://georgiafaces.caes.uga.edu/ge Photosynthesis. The World & I. tstory.cfm?storyid=2281 Retrieved from (Accessed 24 June 2009) http://bioenergy.asu.edu/photosyn/e ducation/photointro.html Shari, Armstrong. How Does Water Affect Plant Growth. 27 http://www.gardeningknowhow.com 31 File Page HO-193. Purdue /children-in-the-garden/how-does- University Cooperative Extension water-affect-plant-growth.htm Service. West Virginia university (accessed June 19, 2009) extension service Space Science Group. Ingredients http://www.wvu.edu/~Agexten/hor for Photosynthesis tcult/fruits/blkwalnt.htm (Accessed 24 June 2009) 28 http://www.spacesciencegroup.nsula .edu/lessons/Default.asp? Theme=plants&pagename=photosy nthesisingredients (accessed on June 19, 2009) Grimm, Scott A. Natural herbicide for weed removal. http://www.freepatentsonline.com/6 756341.html (accessed June 19th, 2009)