Distribution of ergosterol in organically and conventionally cultivated agricultural soils

Ergosterol is generally assumed to be one of the best indicators of fungal biomass and soil quality. The present case studies describe variations in e rgosterol content in soil, sampled at three Danish Farms. One is organicall y cultivated according to the biodynamical principles (ORG). The other two are conventionally cultivated, one with animal husbandry (CONV-H) and one w ith plant production (CONV-P). The analytical method combined extraction in a microwave oven, clean-up with a new SPE sort,ent material (Oasis(TM)), a nd quantification by HPLC. The average estimated concentrations of ergoster ol were 1.66 mug g(-1) in ORG, 2.35 mug g(-1) in CONV-H and 1.13 mug g(-1) in CONV-P. These results correlated well with some of the important variabl es in the management systems of the soils (frequency of grass and clover, i nput of animal manure, total-C, frequency of ploughing). However, the exact causal relationships cannot be revealed using the case-study approach. The statistical analysis of the spatial variation in ergosterol across the fie ld demonstrated very clearly that in some soils, small-scale few cm(2)) var iations in ergosterol concentrations may be quite large in comparison with large scale (few hundred m(2)) variations. This should be taken into accoun t when planning the sampling strategy.