Objective The aims were to explore the effects of different amounts of organic fertilizer on soil improvement and the growth of medicinal peony intercropping maize, and achieve high yield, green and high efficiency for the production pattern of medicinal peony intercropping maize.

Method A total of six treatments with 15, 30, 45, 60, 75 and 90 tons hm⁻² with organic fertilizer from bacterial residue were carried out, and compared with no application of organic fertilizer from bacterial residue. Field plots of intercropping between peony and corn were conducted for five consecutive years to determine the relevant indicators. Compare The effects of different fertilizer application amounts on the growth conditions of medicinal peonies and corn were compared, including the physical and chemical properties of the soil.

Result The contents of organic matter, available nitrogen, available phosphorus and available potassium in soil were increased by the continuous treatment of bacterial residue in the past five years with an average of 11%-53%, 20%-74%, 40%-73% and 13%-45%. Moreover, it could reduce pH and salt contents. The application of organic fertilizer with bacterial residue significantly increased maize plant height, ear height, stem diameter, stem segment number, maize yield, and the yield of vitexanol and paeonol. Meanwhile, the treatment (60 t hm⁻²) had the best effect. Correlation analysis showed that the treatment of organic fertilizer with bacterial residue promoted the growth of medicinal peony and maize by regulating soil nutrient content and reducing soil salinization level, thereby increasing yield.

Conclusion Under the conditions of this experiment, the treatment (with a dosage of 60 t hm⁻² of microbial residue organic fertilizer) had the best effect in improving the physical and chemical properties of the soil and increasing the yields of medicinal peonies and corn. This research result provides a basis for the fertilization of the local medicinal peony-corn intercropping.