Long-term studies on the ecological effects of continuous rye cultivations carried out in Poland are summarized. It was shown that in continuous cropping of rye, despite the decrease of crop yields, no significant difference was observed in annual primary production rates compared with estimates found for rye fields cultivated in diversified crop rotation patterns. In continuous cultivation of rye fauna impoverishment was observed, while at the same time the number of crop pests increased. The animal groups reduced by continuous cropping of rye belong to Protozoa, Lumbricidae, Acarina, and winged insects. The cultivation of rye in continuous cropping influenced the increase of fungi with bacteria and actinomycetes becoming less abundant. In soils under continuous rye the average concentration of phenolic acids was 400% higher than under rye in diversified rotation. Five different phenolic acids were identified. The mean content of bound amino acids in soils under diversified rotation was 417 mg x kg(-1) and in soils under continuous rye cropping was 371 mg x kg(-1). The energetic cost of total soil animal community maintenance calculated per unit of biomass under continuous cropping of rye was almost twice as high as under the diversified rotation. The accumulation of toxic metabolites caused negative effects among biota under continuous cropping of rye.
