The effect of added phenolic acids on soil enzyme activities and nutrients

Pot experiments were carried out to study the effects of added phenolic acids on soil enzyme activities and nutrients in watermelon continuous cropping soil.The results obtained are listed as follows.Hydrogen peroxidase, urease activities and respiration of the soil added with phenolic acids were higher than those of control.Soil respiration,for example,was increased by 22.5% and 20.0% two weeks after the addition of cinnamic acid and P-hydroxybenzoic acid(500 mg/kg) and urease activities were increased by 34.4% and 29.0% four weeks after the addition of the two phenolic acids(750 mg/kg).Soil available N,P,K and organic matter were decreased by the addition of the two phenolic acids.Thus,they were decreased by 9.60%,18.4%,20.7% and 11.0% with the addition of cinnamic acid(250(mg/kg)),respectively.