Long-Term Application of Organic Fertilizers in Relation to Soil Organic Matter Quality

The quality of soil organic matter plays a central role in structure, carbon sequestration and pollutant immobilization. effect 16–23 years fertilization on the was studied field experiments at ten experimental sites Central Europe. Soil samples were collected 2016 after barley harvest. Six crops rotated: pea–canola–winter wheat–spring barley–beet/potato–spring barley. treatments studied: unfertilized control, mineral (NPK), farmyard manure, manure + NPK, straw incorporation, incorporation NPK. Although input did not significantly correlate with any fractions, C/N ratio applied fertilizers correlated content humic acid (C-HA), C-HA/C-FA humification index soil. combination NPK resulted higher soil, rate, compared to application return, return led lower E4/E6 (A400/A600, Q4/6) application, unchanged among these treatments. without addition values efficiency