*2.2. Experimental Design*

The field experiment was arranged as a two-factorial design. The first factor was the nitrogen fertilization system (NFS), related to the type of N fertilizer applied: (i) ammonium nitrate, 34-0-0, (acronym M-NFS), (ii) organic N: digestate (O-NFS), (iii) mixed: 2/3 of digestate + 1/3 of ammonium nitrate (AN) (OM-NFS). The rate of applied N was: 0 (N control), 60, 120, 180, and 240 kg ha−1. Each year, digestate was applied at the end of November, and AN on the 1st of March of the following year. The applied digestate on average contained: DM: 72, N-NH4: 7.2, P2O5: 5.45, K2O: 2.85, MgO: 1.88, S: 1.99 kg m<sup>−</sup>3. Winter barley was a fore-crop for WOSR. A hybrid WOSR variety *Impression Cl,* characterized by a high yielding potential for medium fertile soils, was used as a test crop. It was sown at the rate of 3.0 kg ha−<sup>1</sup> at the end of August and harvested at the end of July from an area of 12 m2. The seeds were harvested at maturity when the moisture content was 8% dry weight.


**Table 2.** Main characteristics of meteorological conditions during the winter oilseed rape (WOSR) growing season on the background of the long-term averages 1.

meteorological station at Szczecin.
