Objective  Improvement effects of straw returning and mixed purple soils was studied to form efficient remediation technology of sandy acid soil and yield & quality of flue-cured tobacco.

  Method  Field experiments were conducted to find the effects of the straw returning and mixed purple soils on physicochemical properties of soil, yield & quality of flue-cured tobacco, which were: no straw and purple soils added as control (T1,CK), straw returning (T2, 3 000 kg·hm⁻²), mixed purple soils (T3,225 m³·hm⁻²), straw returning (3 000 kg·hm⁻²)+ mixed purple soils (225 m³·hm⁻²) (T4).

  Result  Treatments of straw returning and mixed purple soils could improve the soil physical properties. Compared with CK, the soil bulk density were decreased by 6.38%, 2.12 % for T2 and T4,while the soil particle size composition transformed from clayey loam (CK) to loam (T2), silty loam (T3 and T4). Compared with CK, the soil pH, organic matter and Avail. N were significantly improved by T2; the soil pH and available potassium were increased by 1.43 and 19.98 mg·kg⁻¹, respectively. The remarkable improvement of chemical properties of soil was T4, which the pH value, organic matter and available potassium content of tobacco planting soil were 1.21, 1.26 and 1.28 times higher than those of T1 (CK), respectively. Treatments of straw returning and mixed purple soils even could promote the growth of tobacco, improve the economic benefits and quality of flue-cured tobacco. The best effect on economic characteristics of tobacco, chemical composition coordination and sensory evaluation quality in grade C3F of flue-cured tobacco leaves was T4, the yield, output and the proportion of high quality of which increased by 35.04 %, 20.64 % and 38.59 % ,respectively.

  Conclusion  The best improvement effects of acid soil was straw returning (3 000 kg·hm⁻²) cooperated with mixed purple soils (225 m³·hm⁻²). It can effectively improve the physical properties, pH value, organic matter and available potassium content of soil, then achieve economic returns from both sides of tobacco leaves’ yield & quality and the sustainable remediation of sandy acid soil.