Pot culture and field experiments on the response of the yield of wheat and millet to superphosphate were conducted on the calcareous soils of Kwanchung district, Shensi. Chemical properties of the soils were studied. Results obtained showed that the response of the yield of crops to phosphatic fertilizer was largely affected by the amount of available phosphorus and available nitrogen in soils. Soil pH value, the contents of CaCO₃ and total phosphorus in soils gave no significant correlation to the response of crops to phosphatic fertilizer. It was found that the available phosphorus determined according to Olsen's method gave good correlation to biotic experiments. Increase in the yield of crops by the application of superphosphate was found in soils containing available P₂O₅ less than 10 ppm. Adequate supply of available phosphorus in soils became doubtful when this figure ranged 10 to 20 ppm. No response of crops to superphosphate was observed in soil containing available P₂O₅ over 20 ppm. Available nitrogen, as expressed by the amount of nitrified nitrogen after incubation, also showed good correlation of the response of crop yield and phosphatic fertilizer. In soils having available N/available P₂O₅ ratio over 3, crops gave good response to phosphatic fertilizer. The efficiency of phosphatic fertilizer became uncertain in soils with N/P ratio ranging 1 to 3, and nitrogenous fertilizer seemed to be a limiting factor for crop yield as this ratio dropped below 1.