In a field experiment conducted on leached brown soil in Malice, near Zamość (southeastern Poland) in 2007-08, the effect of soil tillage and nitrogen fertilization on microbiological parameters of the soil under spring Triticale cultivation was investigated. Soil tillage – conventional and simplified with double or single cultivation – was combined with different variants of nitrogen fertilization – 60, 90, and 120 kg N·ha^-1. The soil was sampled three times – I - end of tillering stage (BBCH 29), II - end of heading stage (BBCH 59) and III – late milk stage (BBCH 77) – and its microbiological properties were determined.
Generally, the simplified soil tillage and nitrogen fertilization up to 90 kg N·ha^-1 favors bacteria, Actinomycetes, and fungi content, as well as dehydrogenase activity. The conventional soil tillage and nitrogen fertilization at a level of 120 kg·ha^-1 reduced the number of microflora. The highest numbers of micro-organisms in the soil were noted at the stage (BBCH 59) of the spring Triticale, but dehydrogenase activity was highest at that stage (BBCH 29). In formulating the biological index of soil fertility (BISF), the biological activity of the soil (M), organic carbon content (H) and soil absorbing capacity (T) were taken into account. Biological activity of the soil (M) was expressed as numbers of micro-organisms, or as dehydrogenase activity. The BISF, calculated based on dehydrogenase activity, is significantly dependent on the all factors investigated. However, BISF calculated as the sum of the numbers of bacteria and Actinomycetes in relation to fungi (B+A/F) was positively correlated with grain yield. Grain yield was highest following conventional soil tillage and nitrogen fertilization at a level of 60 kg N·ha^-1.