Study an effect of using sulfur - removal waste residue ( the vice - product produced by sulfur - removal device of the factory using coal as energy resource to absorb oxidizing sulfur , whose mainly composition is gypsum ) as an amendment to the alkali soil in theory . with certain water as leaching requirement leaching soil column indoor employed with certain quantity sulfur - removal waste residue after collecting and analyzing representative soil sample . collecting and analyzing the filtrate , then calculate the data and speculate the result to guide the field production