Humus composition of Terra rossa under olive groves in dependence of soil management

Cilj rada bio je utvrditi utjecaj sustava uzgoja u maslinarstvu (ekstenzivni i intenzivni uzgoj) na sastav humusa crvenica. Istraživanje je provedeno na 10 prosječnih uzoraka tla (0-20 cm) od čega 5 u maslinicima s ekstenzivnim, a 5 s intenzivnim uzgojem maslina, na području srednje Dalmacije. U uzorcima je određen frakcijski sastav humusnih tvari, spektroskopski su karakterizirani, te je izračunat optički indeks E4/6. Srednja vrijednost sadržaja humusa bila je viša u intenzivnim maslinicima (6,7 %) nego u ekstenzivnim (5,3 %). Prosječan omjer huminskih i fulvo kiselina (Ch/Cf) u tlima ekstenzivnih maslinika (1,78) bio je viši nego kod intenzivnih (1,26), što upućuje na prosječno bolju kvalitetu humusa. Međutim, u dva uzorka intenzivnih maslinika također je utvrđen najkvalitetniji tip humusa (Ch/Cf > 1,5). Niži prosječan E4/E6 indeks u tlima ekstenzivnih maslinika (3,86) u odnosu na intenzivne (4,63) potvrdio je rezultate klasične analitičke metode. Pri intenzivnom uzgoju maslina kvaliteta humusa je više varirala i bila prosječno niža.The aim of this study was to determine the influence of the cultivation system in olive growing (extensive and intensive) on the humus composition of Terra rossa. The study was conducted on 10 average soil samples (0-20 cm) out of which 5 in olive groves with extensive and 5 with intensive olive cultivation, in middle Dalmatia. Soil samples were analysed for fractional humus composition, spectroscopically characterized and optical index E4/E6 was deteremined. The mean value of humus content was higher in intensive olive groves (6.7 %) in comparison to extensive (5.3 %). The mean value of humic to fulvic acid ratio (Ch/Cf) in the soils of extensive olive groves (1.78) was higher than in intensive olive groves (1.26), which indicates an averagely higher humus quality. However, in two samples of intensive olive groves the highest humus quality was also determined (Ch/Cf > 1.5). Lower mean E4/E6 indeks in soils of extensive olive groves (3.86) in relation to intensive (4.63) confirmed results of classical analytical method. The humus quality in soils under intensive olive groving varied more and in average was lower