Bicarbonate Water Control by Injecting SO2 in Irrigation water

Abstract The great part of plants mineral nutrients such as phosphorous, iron, and zinc will be fixed or will be unavailable since the most soils in Iran are calcareous. So the plant will not able to absorb the plant nutrients. Decreasing soil pH, even for a short period of time, will enhanced the solubility of fixed elements and their absorption will be easier. Application of acidic substances such as sulfuric acid, grinded sulfur or the SO2 gas produced from SO2– permeater apparatus will change the water or soil pH. SO2 permeater was made in 1985 in Soil and Water Research Institute but it could not be used because of technical reasons. This project is designed with the aim of decreasing pH, carbonate and bicarbonate of irrigation water and calculating the amount of consumed materials. The prepared apparatus was installed in the way of irrigation water outlets of 7 different wells in Tehran, Alborz and ghazvin provinces with different range of bicarbonate contents (2.1 – 20.8 m .e./l) in irrigation water. Water sampling were done from water outlet pipe after starting the apparatus. The second and third samples were taken with 15 minutes intervals in three replications. The samples were analyzed for EC, pH, CO3, HCO3, Ca, Mg, Na, and Cl after 24, 48, 72 and 96 hours. The results showed that the water pH and water bicarbonate were decreased at the all sites. The pH of water was lowered between 0.54 – 1.63 m .e. /l, but the water EC increased 0.06 – 0.14dS/m. Ca +Mg, Na, and Cl changes were between 0.006 – 2.9 m. e. /l. The recent results showed that the mixing water and gas before outlet pipe was very important. The pot experiment results showed that irrigation of the pot soils with acidic water lowered the pH of water and neutralized the soil bicarbonate.