Abstract:
One problem about the irrigation in the Country is that more than sufficient amount of water are given to plant leading to a low irrigation efficiency contrasted with the water delivered by irrigation system being high investment and limiting availability of water. Therefore in this research, a more efficient method of irrigation was studied adhering to a principle of giving just sufficient amount of water to plant to satisfy its requirement. The system is computerized controlled so that the watering is programmed to distribute water to plant according to the age of the plant. The irrigation system studied was the sprinkler irrigation which is an efficient system using small amount of water. It can also be modified to give fertilizers and insecticides at the same time of watering by mixing them with water before giving it to plants. Comparison of results is made with the normal irrigation given to plant manually. The preliminary study consisted of designing the sprinkler irrigation system completed with the fertilizer and insecticide injecting system, controlled by a computer with one channel of input signal and eight channels of output signals. Instruction and programs were stored in the ROM of the controlled system which was capable of controlling the water distribution by a probe or a non-probe method. The system components were assembled and employed in an experimental planting area. From the results of the research where red onions were planted in an experiment plot and the water distribution controlled by computer with probe, it was found that the amount of water distributed to plant equaled to the amount of water used by plant and corresponded with the available moisture in the soil. Moreover the amount of water distributed to plant with a non-probe method i.e. without checking the soil moisture also worked equally well thus suggesting that the designed watering time is sufficiently accurate. The fertilizer and insecticide injector system also worked well. In conclusion the computerized control sprinkler irrigation system can efficiently distribute water to plant at the rate very close to the plant requirement and take into account the soil moisture condition. Thus it makes possibility to save water, labour and time of the manually operating system of irrigation. This could possibly lead to the reduction of cost in agricultural production. However it is recommended that more study should be made to develop the computerized control system further so that it can easily be applied with more elasticity and higher efficiency. More studies on larger planting areas with a more complex irrigation system, feasibility study and the effect upon other factors in the agricultural production system should also be made to ensure that they can be applied to further the efficient development of agriculture and irrigation in Thailand in the future.