[Accumulation of phenolic acids in continuously cropped cucumber soil and their effects on soil microbes and enzyme activities].

The study showed that in solar greenhouse continuously cropped cucumber soil, phenolic acids p-hydroxybenzoic acid, ferulic acid and benzoic acid had an obvious accumulation with increasing cropping year, and their contents were significantly higher after continuously cropped for 5 approximately 9 years than for 1 approximately 3 years. With the increasing concentration of treated exogenous phenolic acids, the amounts of bacteria, actinomycetes, total microbes, ammonibacteria, and nitrifying bacteria in cucumber root area increased first, but decreased then. Soil bacteria and actinomycetes had the largest amount at the concentration of 80 microg phenolic acids x g(-1) soil, while soil fungi (including Fusarium and Phytophthora) increased rapidly when the concentration of phenolic acids was lower than 120 microg x g(-1) soil. With increasing phenolic acids concentration, soil enzyme activities also increased first but decreased then, with the peak values differed in different treatments.