Effect of phosphite on soil microbial enzyme activity and the feeding activity of soil mesofauna

The effect of phosphite on the biocoenosis of an arable soil was investigated in a field trial in 2004 - 2005. In particular, the responses of soil micro-organisms and soil mesofauna were objects of the studies. It was shown that no inherent phosphite was detectable in the investigated soil. After the application of phosphite in form of potassium dihydrogenphosphite (KH2PO3) to the upper layer of a grass-grown plot, an adaptation of the soil and the metabolic active soil biocoenosis, respectively, caused at least a partly oxidation of phosphite to phosphate. Microbial enzyme activities demonstrated no significant correlation to soil contents of phosphite and phosphate with exception of dehydrogenase that was correlated to phosphate. The mesofaunal feeding activity was significantly decreased by incorporation of phosphite in combination with mud flat soil originated from the German North Sea.