Water soil erosion in grasscovered and cultivated olive orchards in Polača

Cilj ovog rada je proučavanje načina gospodarenja tlom u maslinicima na svojstva tla, i potencijalnu erodibilnost testiranu kišnim simulacijama gdje se bilježilo površinsko otjecanje (Ov), gubitci sedimenata (Sed g) na rendzini u Zadarskom zaleđu (Hrvatska). U tu svrhu provedene su kišne simulacije (po 8 na zatravljenom i obrađenom masliniku) u intenzitetu od 60 mm/sat u trajanju od 30 minuta, te su prikupljeni uzorci tla pokraj svakog kružnog erozijskog kolektora površine 0,785 m2. Rezultati su pokazali kako je volumna gustoća tla značajno veća na obrađenom tretmanu, dok kapacitet tla za vodu (PKV), srednja veličina strukturnih agregata (SVSA), udio vodostabilnih agregata (UVSA) i organska tvar (OT) imaju više vrijednosti na neobrađenom tretmanu u odnosu na obrađeni. Tretmani nisu značajno odstupali u trenutnoj vlazi tla (Trv) i vremenu do površinskog stagniranja vode (to). Gubitak sedimenta i hraniva (P2O5, N, C, S) u sedimentu značajno je viši na obrađenom tretmanu. Korelacija između varijabli je ukazala da u oba tretmana (zatravljeni i obrađeni) postoji potpuna negativna korelacija između infiltracije (Iv) i Ov, dok je korelacija između Iv, Ov i koncentracije sedimenta (Ys) vrlo jaka sa gubitkom sedimenta i gubitkom hraniva, a gubitak sedimenta i gubitak hraniva su u potpunoj međusobnoj korelaciji. Istraživanje ukazuje da način gospodarenja tlom značajno utječe na fizikalna i kemijska svojstva tla i njegova hidrološka svojstva – infiltraciju i površinsko otjecanje. Rezultati podupiru tvrdnju da je zatravljeni tretman ekološki prihvatljiviji u usporedbi sa obrađenim. Potrebno je šire primjenjivanje takvog načina gospodarenja u maslinicima kako bi se proces degradacije umanjio.The objective of this paper was to study the method of soil management in olive orchard on soil properties and potential erodibility tested by rain simulations, where runoff and sediment losses on rendzine soil in Zadar hinterland (Croatia) were recorded. For this purpose, rain simulations (8 grass-covered and 8 cultivated in olive orchard) were carried out at an intensity of 60 mm/ hour for 30 minutes, also soil samples were collected next to each circular erosion collector with a surface of 0,875 m2. The results showed that the bulk density was significantly higher on cultivated treatment, while the soil water content, mean weight diameter and water stable aggregates, and organic matter had higher values on grasscovered treatments. There was no significant difference between treatments when we watch the results of water holding capacity and ponding time. The sediment loss and nutrient loss (P2O5, N, C, S) were significantly higher on cultivated treatments. The correlation between the variables has shown that in both treatments (grass-covered and cultivated) there was a complete negative correlation between infiltration and runoff, while the correlation between infiltration, runoff and sediment concentration was very strong with sediment loss and nutrient loss, also sediment loss and nutrient loss are completely correlated with each other. Research indicates the method of soil management significantly affects the physical and chemical properties of soil and its hydrological properties – infiltration and runoff. The results support the claim that grass-covered treatments very more environmentally friendly compared to cultivated. There should be a wider application of such management methods to reduce the degradation process