Comparison of soil organic matter characteristics under the energy crop giant red, cropping sequence and natural grass

The objective of this study was to determine, on the same pedological, topographic, and climatic conditions, the effects of a continuous giant reed cropping (GR), a cropping sequence (CS), and untilled natural grass (NG) on some soil characteristics. Selected characteristics included total soil organic carbon (TOC), light fraction carbon (LFC), dissolved organic carbon (DOC), and microbial biomass carbon (MBC). The various humic fractions and their ratios, humification ratio (HR), humification degree (HD), and humification index (HI) were also evaluated. Results indicate that GR, characterized by low tillage intensity, showed greater values than tilled management system (CS) for all the previously mentioned properties, with the exception of the humification parameters, which were not statistically different between the two systems. Regarding the difference between GR and NG (the latter usually considered as a reference or baseline for evaluating attributes of soil quality), GR generally showed greater values for all organic parameters, with the exception of MBC and humus characteristics.