Interpretation of Soil Water Quality for Agricultural Production

Langelier (1936) described the state of saturation of natural waters with respect to CaCO₃ by Equation 1, 1% MathType!MTEF!2!1!+- % feaagCart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4uaiaadg % gacaWG0bGaamyDaiaadkhacaWGHbGaamiDaiaadMgacaWGVbGaamOB % aiaaykW7caWGjbGaamOBaiaadsgacaWGLbGaamiEaiabg2da9iaadc % hacaWGibWaaSbaaSqaaiaad+gaaeqaaOGaeyOeI0IaamiCaiaadIea % daWgaaWcbaGaam4yaaqabaaaaa!4D21!]]</EquationSource><EquationSource Format="TEX"><![CDATA[$$Saturation\,Index = p{H_o} - p{H_c}$$ where, pH_o is the observed pH of a solution and pH_c is the calculated pH that the same solution would have if it was saturated with CaCO₃, but with no alteration in ionic composition. In effect, positive values of the Saturation Index mean that solutions are supersaturated with respect to CaCO₃ and there will be a tendency for carbonate to be deposited. This tendency is aggravated by temperature increases since the solubility of CaCO₃ decreases at elevated temperatures, such as are experienced in hot water systems.