Kvaliteta humusa u crvenicama pod maslinicima s različitim načinima gospodarenja tlom

The paper aimed to determine humus quality in Terra rossa soils under olive groves with different soil management types. A total of 10 top-soil samples (0-20 cm) were collected in olive groves of Middle Dalmatia, Croatia, out of which 5 were from the traditional low-input olive groves (TOG) and 5 in the intensive olive groves (IOG). The soil samples were analyzed for basic soil properties, soil organic carbon (SOC), and fractional composition of humic substances. Spectroscopic characterization of humic substances was carried out by measuring absorbance in the VIS spectral range (400-700 nm). Optical index E4/E6 (ratio of optical absorbance at 465 to 665 nm for humic substances in solution) was calculated. The mean value of SOC in soils under TOG (3.06%) was lower than in soils under IOG (3.88%). Higher variations of carbon in humic (CHA) and fulvic acid (CFA) were observed in the soils under IOG. The mean CHA/CFA ratio in soils under TOG was higher than in soils of IOG (1.78 and 1.26, respectively). The soils under TOG had fulvic-humic to humic types, while the soils of IOG had humic-fulvic to humic types of humus. A lower mean E4/E6 index of soils under TOG than IOG (3.78 and 4.36, respectively) confirmed the results of the classical analytical method. Our findings reveal higher variation and lower humus quality in soils under intensive olive cultivation.Cilj rada bio je utvrditi kvalitetu humusa u crvenicama pod maslinicima s različitim načinom gospodarenja tlom. Ukupno je uzeto 10 površinskih uzoraka tla (0-20 cm) iz maslinika Srednje Dalmacije, Hrvatska, od čega 5 iz tradicionalnih maslinika (TM) i 5 iz intenzivnih maslinika (IM). Uzorci tla su analizirani na osnovna svojstva tla, organski ugljik (OC) i frakcijski sastav humusnih supstanci. Spektroskopska karakterizacija humusnih supstanci provedena je mjerenjem absorbance u VIS spektralnom rasponu (400-700 nm). Izračunat je optički indeks E4/E6 (odnos optičke apsorbance kod 465 prema 665 nm za humusne supstance u otopini tla). Srednja vrijednost OC u tlima pod TM (3,06%) bila je niža nego u tlima pod IM (3,88%). Veća variranja ugljika u huminskim (CHA) i fulvo (CFA) kiselinama uočena su u tlima pod IM. Prosječni CHA/CFA odnos u tlima pod TM (1,78) bio je viši nego u tlima pod IM (1,26). Tla pod TM imala su fulvično-huminski do huminski tip, dok su tla pod IM imala huminsko-fulvični do huminski tip humusa. Niža srednja vrijednost E4/E6 indeksa u tlima pod TM (3,78) u odnosu na IM (4,36) potvrdila je rezultate klasične analitičke metode. Naši rezultati otkrivaju veće variranje i nižu kvalitetu humusa u tlima pod intenzivnom maslinarskom proizvodnjom