Abstract: This paper was conducted to study the abundance and deficiency indices of phosphorus and potassium of winter wheat under the conditions of straw returning and soil fertility having changed significantly.Adopted grading methods to study the polynomial regression between the relative yield of wheat grain in lack fertilizer plots and whole fertilizer plots and the content of available nutrients in soil,the test analysed the abundance and deficiency indices of soil nutrients.The results indicated that the content of available phosphorus<2.4 ms/kg was extreme lack of available phosphorus；the content of 2.4-10.3 ms/kg was severe lack；the content 10.3-18.5 rag/kg Was moderate lack； the content of 18.5-33.3 ms/kg was medium；the content>33.3 mg/kg Was abundance the content of available potassium<30.5 mg/kg was extreme lack of available potassium；the content of 30.5-67.2 mg/kg was severe lack： the content 67.2-92.0 mg/kg Was moderate lack；the content of 92.0-126.5 ms/kg Was medium：the content was >126.5 ms/kg was abundance.compared to the abundance and deficiency indices established in 1980s-1990s,the indices had significantly increase.

Key words: Taihang mountain piedmont plain, Winter wheat, Abundance and deficiency indices of phosphorus and potassium

CLC Number: 

• S143