Influência da aplicação de gás carbônico na redução de precipitação de carbonatos em sistema de irrigação localizada

Abstract

The drip irrigation system is the most efficient water use, since it maintains the necessary moisture to the plants, reduces water consumption for irrigation increases crop yields and reduce leaching in soil being basic to the sustainability of agriculture, especially in arid and semiarid regions. However, many of these areas as the north of Minas Gerais, have alkaline groundwater with high carbonate hardness, which limits the use of drip irrigation due to clogging of the emitters of water. This study aimed to evaluate the reduction of water pH and the clogging of emitters due to the precipitation of carbonates with CO2 injection, water via irrigation frequencies once every two days, once a week and two in two weeks in a pilot system of drip irrigation. The variables were: pH, alkalinity, variation of the emitter discharge and coefficient of uniformity of water application of Christiansen (CUC). The water used in irrigation is a water of high carbonate hardness is classified as hard, medium risk of clogging of emitters with respect to hardness, alkalinity, the Fe+2 and Mn+2, without risk of soil salinization. It was observed that the pH of saturation in CO2 to the water (5.5 to 6.0) is within the range of soil pH ideal for crops, which is between 5.5 and 6.5. The best result in the maintenance of uniformity of water application was obtained with irrigation with carbonated water for an hour every two days. It was concluded that injecting CO2 into the saturation concentration is effective in reducing the clogging of drippers for calcium carbonate for irrigation, using water with alkalinity around 250 ppm CaCO3, reducing by more than 35% Clogging.