二、 Soil alkalinity (- The cause of soil alkalinity 1, Calcium carbonate hydrolysis Caco, +H,0 Ca2++HCo3-+OH CO+HO- HCO3-+H 2 Sodium carbonate hydrolysis ()2NaHCO Na.,+,o+co (2)Na2SiO3+ H2CO3- Na2CO3+SiO2+H2O ()CaCO3+NaCl -CaCl2 Na2CO3 CaCO3 Na2SO4 CasO4+ Na2 CO3二、Soil alkalinity （一） The cause of soil alkalinity 1、Calcium carbonate hydrolysis CaCO3 + H2O Ca2+ + HCO3- + OH￾CO2 + H2O HCO3- + H+ 2、 Sodium carbonate hydrolysis (1)2NaHCO3 Na2CO3+H2O + CO2 (2)Na2SiO3 + H2CO3 Na2CO3 +SiO2+H2O (3)CaCO3 +NaCl CaCl2 + Na2CO3 CaCO3 + Na2SO4 CaSO4+ Na2CO3