A pot experiment was conducted to clarify the mitigation effect of liquid organic fertilizer on continuous cropping obstacle caused by phenolic acid in soil. Ferulic acid and vanillic acid were mixed equally and applied to potato substrate soil at different concentrations (0

50

100 and 150 mg/kg) to simulate the autotoxin substances secreted by potato continuous cropping

and different concentration gradients liquid organic fertilizer (0

225

450 and 675 kg/hm2) were applied to clarify the effects of liquid organic fertilizer on potato growth and soil enzyme activity under phenolic acid stress. The results showed that single exogenous phenolic acids reduced the potato plant height

stem diameter

leaf area and dry weight in different degree. With the increasing of phenolic acid concentration

the activity of urease

acid phosphatase and invertase in soil decreased by 2.74%~10.95%

11.11%~20.55% and 5.29%~12.96% compared with the control

respectively

the activity of catalase and polyphenol oxidase increased

while FDA hydrolase activity showed low promotion and high inhibition. Applying liquid organic fertilizer improved the potato plant height

stem diameter

leaf area and dry weight. Soil enzymes activities all increased

the activity of urease

acid phosphatase

invertase

catalase

polyphenol oxidase and FDA hydrolase increased by 10.80%

21.40%

18.20%

29.60%

37.69% and 12.31% at most

respectively

compared with the control. But excessive concentration of liquid organic fertilizer decreased its enhancement of activity of phosphatase

urease and catalase

and inhibited the activity of FDA hydrolase. Therefore

reasonable application of liquid organic fertilizer could promote the growth and development of potato

improve soil enzyme activity and enhance the stress resistance of potato

thereby alleviating the phenolic acid stress on potato.