Soil organic matter content according to different management system within long-term experiment

Within the long-term field experiments at IOSDV Rakičan, Slovenia, the impact of organic matter management system and mineral nitrogen fertilization on the soil organic matter content was studied in the period 1994-2008. The annual balance of Corg was calculated on the basis of the quantity of added organic fertilizers ("Bavarian method", "VDLUFA method"), while the "Swiss method" also consider the quantity of Corg in the topsoil in the calculation. The following management systems were selected: system A - no organic matter, system B - farmyard manure ploughing in, system C - straw/catch crop ploughing in. Four different mineral N rates (N0, N1, N2, N3) were evaluated. In 2008 the Corg content in topsoil (0-25 cm) was measured according to ISO 10694. Farmyard manure (FYM) fertilization significantly influenced the content of Corg, while the straw application did not result in the significant increase of Corg content. Mineral nitrogen fertilization did not impact Corg content within system A. In system B and system C positive effect of nitrogen fertilization on the Corg content was detected. However, statistically significant impact of mineral N on a higher Corg content was not determined. All three methods underestimated the actual analysed results, although, we can determine the "Swiss method" as the most precise and appropriate for this site-specific location.