Impact of soil erosion in hillslope vineyards on soil hydraulic parameters

Kod poljoprivrednih tala brdskih područja erozija može imati značajan utjecaj na svojstva tla i distribuciju horizonata. Mnogobrojni vinogradi se nalaze na brdskim pozicijama zbog povoljnih mikro klimatskih uvjeta, ekspozicije terena i pedoloških karakteristika. U takvim uvjetima tijekom oborina većeg intenziteta može doći do površinskog otjecanja i erozije tla. Infiltracija oborina (ili navodnjavanja) s obzirom na hidrauličke karakteristike određene pozicije na obronku može uzrokovati razlike u vodnoj bilanci obronka. Cilj rada je provesti mjerenja infiltracije tla i odrediti hidrauličke karakteristike tla na različitim pozicijama na obronku (vrh, sredina i dno) kako bi se utvrdio utjecaj erozije na hidraulička svojstva tla i tok vode. Za terenska mjerenja korišteni su procjedni lizimetri za prikupljanje perkolata te za mjerenje infiltracije mini disk infiltrometar, dok su mjerenja u laboratoriju provedena na HYPROP uređaju. U lizimetrima na dnu obronka prikupljeno je dvostruko više perkolata nego na vrhu obronka. Rezultati površinskog mjerenja infiltracije nisu pokazali značajne razlike u hidrauličkoj vodljivosti tla dok su rezultati potpovršinskog mjerenja ukazali na statistički značajne razlike u hidrauličkoj vodljivosti tla u nesaturiranim uvjetima s obzirom na poziciju na obronku. Također su dobivene statistički značajne razlike u količini vode u procjednim lizimetrima između vrha i dna obronka u periodu s većom količinom oborina i većom relativnom vlagom tla. Terenske rezultate potvrdila je i laboratorijska HYPROP metoda određivanja hidrauličke vodljivosti tla. Provedena istraživanja ukazuju na razlike u hidrauličkim karakteristikama tla i toku vode na različitim pozicijama u vinogradarskim brdskim područjima (Ks_vrh=1,71 cm dan-1, Ks_dno=7,16 cm dan-1) te je sukladno tome potrebno prilagoditi gospodarenje na navedenim površinama.In agricultural fields on hillslope areas, erosion can have a significant impact on soil properties and horizon distribution. Numerous vineyards are located on hillslope locations due to the favorable micro climatic conditions, terrain exposition and pedological characteristics. In such conditions and during high intensity precipitation events, surface runoff and soil erosion may occur. Water infiltration (precipitation or irrigation) depends on soil hydraulic properties, which may vary according to a certain position on the slope, causing differences in the water balance of the different parts of the hillslope. The aim of the study is to measure soil infiltration and to determine soil hydraulic properties at different positions on the slope (top, middle and bottom) in order to estimate the impact of erosion on soil properties and water flow. For field measurements, wick lysimeters were used for collecting leachate, while mini disc infiltrometer was used for the estimation of infiltration. Additionally, soil hydraulic properties were determined on HYPROP device using evaporation method. Compared to the lysimeters at the top of the slope, double amount of leachate was collected in the lysimeters at the bottom of the slope. Although results of surface infiltration measurements did not show significant differences in the soil hydraulic conductivity, sub-surface measurements showed significant differences between soil hydraulic conductivity in unsaturated conditions and with a respect to the position on the slope. Additionally, in the period with higher precipitation and high soil water content, significant statistical differences were observed between the amount of leachate collected in lysimeters at the bottom and top slope position (bottom>top). Field results were confirmed by the laboratory HYPROP method for determining soil hydraulic conductivity, which also showed that soil hydraulic conductivity was larger at the bottom slope position compared to the top slope position (Ks_top=1,71 cm day-1, Ks_bottom=7,16 cm day-1). This study showed that soil hydraulic characteristics and water flow may vary with a respect to different positions on the hillslope, thus management practices should be adapted according to the vineyard position on the slope (top or bottom)