Responses of grassland soil nematodes and protozoa to multi-year and single-year applications of dairy manure slurry and fertilizer

Populations of micro-fauna were also assessed through 1998 and 1999 in subplots that had been treated with manure or fertilizer for four years and stopped receiving manure or fertilizer in 1998, and in subplots given manure in 1998 that had previously either been fertilized or left untreated. Protozoa and bacterivorous and fungivorous nematodes remained more abundant through 1998 and 1999 in previously manure-treated plots than in previously fertilized plots, indicating that the cumulative effects of manure application on enhancement of microbial production can be detected through at least two growing seasons after applications cease. Application of manure for one year to previously non-treated or fertilized soil raised the abundance of protozoa and bacterivorous and fungivorous nematodes to levels comparable to continuously manured soil.