Abstract: This objective was to explore the characteristics of soil nutrients and grain yield of rice under different long-term fertilization regimes in a double cropping rice system.A long-term experiment was established in 1986 in Ningxiang county of Hunan Province,China,and five different fertilizer treatments were applied:no fertilizer input (CK),mineral fertilizer alone (MF),rice residue and mineral fertilizer (RF),30% organic matter and 70% mineral fertilizer (LOM),and 60% organic matter and 40% mineral fertilizer (HOM).We analyzed the soil nutrients and grain yield of rice with the above five treatments using the conventional experimental analysis methods.The results showed that after 31 years,the soil nutrients content were improved under long-term combined use of chemical fertilizer and organic manure condition.Meanwhile,the soil organic matter (SOM) was increased under long-term combined use of chemical fertilizer and organic manure condition.Furthermore,the SOM were significantly higher when treated with HOM than that in the LOM,MF,RF,or CK treatments at the mature stage of late rice.Compared to the CK and MF treatments,the total N,P and available N,P,and K increased due to the combined application of chemical fertilizer and organic manure.But there was not significant difference in the total K and value of pH among the five treatments.The results also indicated that the grain yield of rice was increased under long-term combined use of chemical fertilizer and organic manure condition.The grain yield of early rice with HOM,LOM was higher than that of the other treatments,and the grain yield of late rice with RF,LOM was higher than that of the other treatments,respectively.Compared to the CK,the grain yield of rice increased by 97.67% and 95.01% when treated with HOM and LOM,at the early rice,respectively,and increased by 103.64% and 93.97% when treated with RF and LOM at the late rice,respectively.By analyzing the correlation between soil chemical properties and rice yield,there was a significantly positive correlation coefficient between SOM and total N,total P,available N,P (r=0.993^**,0.971^**,0.950^**,0.950^**).And there was significantly positive correlation coefficient between SOM and available K (r=0.802^*).As a result,combined use of chemical fertilizer and organic manure is important way for high yield of rice and improvement of soil fertility.

Key words: Double cropping paddy field, Long-term fertilization, Organic-inorganic fertilizer combination, Soil nutrient, Rice yield

CLC Number: 

• S143.1

• S158