Farmers and gardeners have problems regarding on weeds because weeds destroy the crop thus deceasing the yield. Many methods about weed management have been used in reducing weeds in the field. Some are chemicals and some are environmental. Soil solarization is one of the methods used in weed management. This method uses the principle that heat is trapped and this heat energy will used to lessen the growth of weeds. The experiment consists of two cases. Case 1 relates the effect of the thickness of the material to soil solarization.
Thin materials will tend to eliminate more weeds than thicker polyethylene sheet. In the second case, the effect of different color of polyethylene sheet was determined. Clear polyethylene sheet will have a good weed management than black polyethylene sheet because clear polyethylene sheet will capture more heat energy than black polyethylene sheet.I. INTRODUCTIONWith the rise of the prices of chemical pesticides, farmers and the agriculture sector wants to have a system in eliminating this pest in their crops that is cheaper and more environment friendly. With this, farmers and gardeners devised a new system in reducing the pests in their crops.Soil solarization is an environment friendly method used in diminishing the pest, especially weeds with the use of the heat generated by Sun. A plastic sheet is used to trap the heat and solar energy from the Sun.
The developed heat will use the uncomfortable condition of the pest (weed) and will in turn kill the pests. (Frank Westerlund, 2002) This method was known as plasticulture. The more reliable meaning of plasticulture is an integrated system and utilization of plastic mulches. The advantages of this method are, there can be earlier crop production, the yield will increase, the yield will have higher quality, reduces water reduction, fertilizers will be used efficiently, soil and wind erosion will reduced, and there will be fewer weeds. (Earles, 2000)Background of the StudyWith the popularity of solarization and plasticulture in reducing the pests and weeds in a filed, many experiments and studies were conducted to further understand the principle and mechanism of the said method. It was found out that raising the soil temperature in 60OC after 30 minutes is the recommended soil temperature that will be used in reducing pests. Grooshevoy studied the effect of solarization Thielaviopsis basicola on the roots of tobacco seedlings. Soil solarization is usually done during warm season.
Soil solarization uses the principle of mulching process. This process will help the growth of the plant, limit evaporation rate and limit the growth of weeds. (Irmaileh, 2006)Objective of the studyThe overall objective of the study is to determine the feasibility of soil solarization using polyethylene sheet as a method in weed management. The specific objectives of the study are:To determine the efficiency and applicability of soil solarization using different thickness of polyethylene sheet (2mm, 4mm, and 6mm thicknesses).The second specific objective is to determine the effects on weed management of soil solarization using transparent and colored polyethylene sheet.
II. METHODOLOGYMaterialsThe materials to be used in this experiment are:Nine black polyethylene sheet (the first six has a thickness of 2mm, the other three has a thickness of 4mm and the last three has a thickness of 6mm)Three clear (transparent) polyethylene sheet with thickness of 2mm.Plants seedlings with the same height, weight and species.
Green weed samples with the same height, weight and species.ThermometerFactors and Parameters to be consideredThe experiment will be done in a warm season with the same environment conditions like the outside temperature, relative humidity, wind speed and direction, rainfall pattern. The soil to be used will be the same in soil texture, soil classification, soil bulk density and other properties of soil.MethodsThe experiment will have two cases.
In the first case, the three different black polyethylene sheets with different thickness will be used. These are the 2mm, 4mm, and 6mm thick. There will be three runs that will be conducted. Every run will compose of each of the given three thicknesses. All the three runs will be planted with one seedling plants and will be surrounded with the same amount of weeds. Each run will be trapped with polyethylene sheet. The three runs will be done in a different days with the same time on the clock.
This means, the first run will be done in the first day, the second run in the second day and the third run on the third day. The second case is the same as in the first except that the introduction of the clear polyethylene sheet. Both have the same in thickness.After a month long duration, the weeds on the first case will be examined and observed as well as in the second case. In both cases, the temperature of the soil will be determined using a thermometer every day.ResultsIn the first case were three black polyethylene sheets with different thickness, the results showed that the weeds are dry and does not contain the green color of the weeds. The results in the three runs for the first case are the same for the same thickness. In the 2mm.
thickness, the weeds samples are dry, withered, and the soil is moist. In the 4mm. thickness, weeds samples are also dry and withered and in the 6mm thickness polyethylene sheet. But the weeds in the 2mm. thickness show the most dried results. The temperature of the three runs shows that the soil temperature in the 2mm thickness polyethylene sheet shows the highest recorded temperature.
In the second case, the weeds in the black polyethylene sheet are dried and withered and in the clear polyethylene sheet, the weeds are yellow-green in color. The soil in both runs is moist. But the temperature in the clear polyethylene sheet is higher compared to the black polyethylene sheet. The mortality rate in the clear polyethylene sheet is greater compared to the black polyethylene sheet.
DiscussionTemperature is vital in the growth of pants and also of weeds. Some plants are susceptible in high temperature while some are not. This case also holds on weeds. The sudden change of temperature on the weeds is not good for the growth thus reducing the weeds in a field. There is a specific temperature where a weed will start to dry. Soil moisture is also vital in the growth of weeds. Soil moisture increase heat transfer between the moist soil to the weeds.
Many weeds species are vulnerable in high temperature. The thickness of the black polyethylene sheet with different thickness shows different results and the temperature in the 2mm. has the highest temperature.
This can be explained by the concept of convection and conduction. The result cannot be explained in the radiation concept because the runs were done in the same intensity of the solar radiation. Convection is the transfer of heat through the movement of hot matter. Warm air surrounding the covered crop increases the temperature inside the polyethylene sheet. Conduction is the transfer of heat because of heat difference. Conduction is dependent on the thickness of the material. Heat is inversely proportional to the thickness, thus thicker materials will conduct heat lesser compared to thin materials. (eFunda, 2006)In the second case, there is a different result on the black and clear polyethylene sheets.
The black polyethylene sheet inhibits the entrance of light. Solar light is vital in the growth of weeds. If this is not given in the right amount, there will be an abnormal growth in the weeds thus reducing the weeds population.
In the clear polyethylene sheet, higher temperature was observed. This is because the entrance of the solar light in clear polyethylene sheet is faster than black polyethylene sheet. (Earles, 2000)ConclusionThere are many factors to consider in testing the feasibility of soil solarization using polyethylene sheet as a method in weed management. These are species of the weeds, temperature, relative humidity, wind velocity and direction, soil properties and the material used in covering the crop.
Thin black polyethylene sheet will be the best materials compared to thicker materials because of the ease in the entrance of heat energy. While clear polyethylene sheet will generate more heat than black polyethylene sheet.