Soil organic matter evolution in organic agriculture soils, under two different cultural precession

The effect of the cultural precession on humic acids (HAs), fulvic acids (FAs), and labile carbon fractions was evaluated in a 2 years experiment. There is evidence that vegetal residues, including those from crop rotations, can be incorporated into soil, affecting soil organic matter (SOM) chemical characteristics. In this preliminary study alfalfa cultivation affected positively both labile and humic SOM content, determining a residual effect that it is still evident after two years. The cultivation of winter wheat determined the mineralization of a significant aliquot of the SOM, both within the labile and humic fraction. The subsequent cultivation of chickpea allowed restoring part of the depleted soil organic C (SOC) pool, particularly within the humic fractions.