Impact of pH on Microbial Biomass Carbon and Microbial Biomass Phosphorus in Red Soils

摘要

The impact of pH changes on microbial biomass carbon (C_(mic)) and microbial biomass phosphorus (P_(mic)) were examined for 3 red soils under citrus production with different lengths of cultivation. Soil pH significantly affected C_(mic) and P_(mic). The C_(mic) and P_(mic) changes, as a function of soil pH, appeared to follow a normal distribution with the original soil pH value at the apex and as pH increased or decreased compared to the original soil pH, C_(mic) and P_(mic) declined. Moreover, there were critical pH values at both extremes (3.0 on the acidic side and 8.0 to 8.5 on the alkaline side), beyond which most of microorganisms could never survive. The effect of pH on C_(mic) and P_(mic) was also related to the original soil pH. The higher the original soil pH was, the less C_(mic) or P_(mic) were affected by pH change. It is suggested that soil microorganisms that grow in a soil environment with a more neutral soil pH range (i.e. pH 5.5- 7.5) may have a greater tolerance to pH changes than those growing in more acidic or more alkaline soil pH conditions.