3年磷石膏后效观察试验结果表明 :磷石膏在黄泥土上增产作用有明显的后效 ,但土壤和施用量不同 ,持续时间不一样。酸性黄泥土以 10 0～ 150 kg/ 6 6 7m2 后效较明显 ,持续时间超过三季作物 ;微酸性黄泥土只有 150 kg/ 6 6 7m2 的后效明显 ,持续时间达到三季作物。磷石膏的改土作用也有后效 ,但与供试土壤 p H值有关。土壤 p H值低 ,磷石膏的后效明显 ,持续时间较长 (三季作物 ) ;土壤 p H值高 ,后效作用不很明显 ,持续时间较短。因此 ,磷石膏宜在 p H值低于 5.0的酸性土壤上施用 After 3 years of phosphogypsum after-effects observation test results show that: phosphogypsum in yellow soil yield significantly after the effect, but the soil and the application rate is different, the duration is not the same. Acidic yellow soil after 10 0 ~ 150 kg / 667m2 after more obvious effect, the duration of more than three seasons of crops; slightly acidic yellow soils only 150 kg / 6 67m2 obvious after-effects, the duration of the three seasons crops. Phosphogypsum soil improvement effect also after effect, but with the soil p H value of the test. Soil p H value is low, phosphogypsum after-effects obvious, longer duration (three seasons crop); soil p H value is high, the after-effect is not obvious, the duration is short. Therefore, phosphogypsum should be applied on acid soils with p H values ​​below 5.0