The old calcination-mathod for disintegrating limestone is still useed prevailingly for rural service in this country.Field practice reveals that soils receiving quicklime,prepared from calcination of limestone with certain kind of coal,give a better yield of rice than those taking quicklime preloLred from calcination with wood-fuels.Extensive analytical results show that owing to the high content of sulphur in such kind of coal,the resulting product of calcined liming material contains 1.8-27% of CaSO₄.The beneficial effect of gypsum to rice cultivation is confirmed in field trial with following treatments:(i) control;(ⅱ) quicklime;(ⅲ) quicklime+gypsum;(ⅳ) calcined liming material prepared from sulphur-coutaining coal.Results show a 9-19% increase of grain yield in plots having experienced treatments (ⅲ) or (ⅳ) in comparison with that in the plot having undergone treatment (ⅱ).The date of rice ripening is about 3-5 days earlier in plots treated by the last two ways than in other plots.