Influence of urea and superphosphate fertilizers on microarthropod numbers and fungal activity during a short-term incubation of material from aPinus radiata D. Don forest floor

Urea and superphosphate dramatically increased the concentrations of exchangeable ammonium-N and water-soluble P in incubated forest floor samples. Urea also increased absolute but not relative nitrate production. Superphosphate depressed pH while urea elevated it.

Microarthropod numbers and fungal activity were depressed by fertilizer addition. Mites were more sensitive to urea than were collembola, which were more sensitive to superphosphate. Both groups were more adversely effected by superphosphate than urea. In contrast, fungal activity was more retarded by urea than superphosphate. It is uncertain whether the observed changes resulted from increased osmotic potentials, pH or pH induced toxicities.