„15th ALPS - ADRIA SCIENTIFIC WORKSHOP - FROM SOIL TO FOOD
25th April – 30th April 2016 Mali Lošinj, Croatia1
SHORT GUIDE FOR ONE-DAY FIELD EXCURSION TO ISLAND SUSAK
1. IN SHORT ABOUT ISLAND SUSAK
Susak is the Croatian Adriatic island in the archipelago
of Cres-Losinj. The island is geologically different from
other Croatian islands, formed from layers of loess
resting on a limestone cliff. On the island there is only
one place, Susak. The island has an area of 3.8 km2,
and the height above sea level is 98 m. Experienced
sailors agree in the fact that in the entire
Mediterranean there is no similar island. The island has
no roads and no cars - just miles of dusty paths that
cascades across the grassy village merged with the now
largely abandoned terraced agricultural areas and
distant bays. During the winter, the island has only
about 150 residents of Susak considering that most
immigrated to the United States. During the 60s of the
last century began mass exodus. Around 1400
residents of Susak has left the island for political and
economic reasons. Anyone who is not rowing boats
fled to Italy and from there on the United States - New
Jersey.
2. BASIC GEOLOGICAL CHARACTERISTICS OF ISLAND OF SUSAK
The island of Susak belongs to the Adriatic carbonate platform. Adriatic carbonate platform is
composed of a succession of carbonate deposits up to 8,000 m thick of Middle Permian – Eocene
age. Carbonate basement of the island is composed of Cretaceous (Cenomanian-Turonian) and
Eocene limestones (Figure 1). Carbonate basement of the island dips towards the east. This
orientation is the same as the West Istrian tectonic structures, making it very likely that Susak
belongs to the West Istrian autochthon of the Northern Adriatic Carbonate Platform
(Mamužić, 1973). The faults in the carbonate rocks are characterized by typical NW-SE Dinaric
spreading direction. Carbonate basement is covered by Quaternary sediments i.e. loess, loess
derivatives and sand, intercalated with many palaeosols and at least three tephra layers. The
thickness of Quaternary sediments is up to 90 m and is the largest in the northern part of the island.
The island has all characteristics of a loess plateau developed on a flat basement. In addition to the
loess plateau, common are gorges and slopes, usually covered with vegetation (Figure 2).
1
Report prepared by: prof. Ivica Kisic ([email protected]), prof. Stjepan Husnjak ([email protected]) &
prof. Goran Durn ([email protected])
1
Figure 1 Simplified geological map of the island of Susak (Wacha et al. (2011); according to Mamužić
(1965))
Loess on the island of Susak is connected to the loess region of the northern Adriatic, and, in addition
to Susak is also present in the marginal areas of the Alps and Apennines, Istria (Savudrija,
Premantura) and on the islands of Krk, Srake, Unije, Lošinj, Hvar and Mljet. Previous research has
shown that the most important and largest source of material for the North Adriatic loess is river Po,
which runs along the northern Italy and flows into the Adriatic Sea. Siliciclastic detritus of the river Po
mostly originates from the Alps, and partly from the Apennines.
Loess on the island of Susak has fluvial and fluvio glacial origin and was formed during the
Pleistocene marine regression due to the transport from the Po valley. During the loess formation,
sea level in the Adriatic was about 120 meters lower, and the Northern Adriatic was a closed basin
with high input of fluvial material (Figure 3). It is believed that the depression in carbonate basement
on the island enabled the accumulation of thick loess cover. Climate variations are clearly visible in
the loess-paleosol sequences, where the warmer periods are characterized with poorly developed
brownish-red paleosols. The researchers recognized 11 palaeosols and at least 3 tephra layers
intercalad within loess, loess derivate and sand. Mineralogical and geochemical analyses showed
good correlation of tephra with volcanic province of Southern Italy. It is believed that the red
paleosol situated directly on carbonate basement below thick loess succession (Figure 4) formed
during the last interglacial (Riss-Würm). Carbonate concretions situated in the upper part of red
paleosol formed due to dissolution of carbonate mineral phases from loess cover and subsequent
accumulation in less permeable paleosols.
2
Figure 2. Loess deposits on the island of Susak
Figure 3. Borders of the Adriatic Sea during the Würm glaciation (taken from Velić et al., 2011)
Figure 4. Carbonate basement and red paleosol - start of the Quaternary loess-paleosol sequences
3
During the 2014 extensive geological and pedological investigation was performed on the island of
Susak within the bilateral Croatian-German scientific project entitled: Tools for modelling past and
future global climate change: Case study of loess-palaeosol sequences (Quaternary aeolian deposits)
from Istria and Kvarner (North Adriatic area). First results estimate an age of 115.9 ± 12.8 ka for
oldest loess, and 108.7 ± 84 ka for red paleosol (Figure 4). Based on this, we can tentatively conclude
that the red paleosol formed during the Eemian period, while the reworked loess substrate from
which this soil was formed probably deposited during the OIS 6 (or older).
3. THE BASIC PEDOLOGICAL FEATURES OF THE ISLAND OF SUSAK
The island of Susak marks the specific lithological structure consisting of sandy loess carbonate
almost from sea level up to a maximum elevation of 98 m. Such a material has in the past been
subjected to intense erosion processes, of which the most important are oozing and undercutting
rainwater, surface wash the soil floods and abrasion sea. Water erosion have been created on the
island very the distinctive water-worn ravines and ravines. Over the past decade after the cessation
of use of agricultural land and intensive of wound natural vegetation, erosion processes are
significantly slowed. Acknowledging the great human influence, mention parent substrate, a
Mediterranean climate and relief, on the island are predominantly developed following soil: rigosol,
rendzina and sirozem.
Table 1: Types of recens soil on the island of Susak (according to the classification of Croatian Soil &
WRB classification)
Type of soil
Lower systematic units
Reference group of soils according to WRB
classification
Rigosol
vineyards, medium deep rigosol,
Hortic Anthrosols
carbonate
Sirozem
on the carbonate sandy loess,
Regosols
carbonate
Rendzina
on the carbonate sandy loess are Mollic Leptosols
carbonate and soak in lye
Table 2: Basic analytical data for rigosol of vineyard on the terraces
Depth
cm
Horizon
0-40
40-80
100-150
IP
II P
C
Soil reaction
(pH) in the
water
KCl
7,6
7,4
7,8
7,6
7,7
7,5
CaCO3
%
Humus
%
N
%
C:N
P2O5
K2O
25,1
20,9
30,1
0,5
0,4
0,04
0,03
7,5
5,7
mg/100 gr soil
0,5
6,6
0,4
6,1
Clay
%
8,6
11,1
17,2
The texture
of the
ground
Loam
Loam
Loam
Rigosol are anthropogenic soil in the sandy loess material are deeply processed soil over 0.5 m deep,
and mostly terraced for the purpose of wine production. They are characterized by P-C timber
profile, the carbonate, slightly alkaline reaction and waters relations.
Sierozem is underdeveloped soil on sandy loess have been developed only on the slopes with a
strong inclination. It is characterized by (A) -C timber profile, alkaline reaction, and great
susceptibility to erosion processes.
Rendzina is accumulating humus soil A-C material profile. It occurs on the flattened parts of the
terrain and is characterized by alkaline soil reaction, carbonate status, favourable humus and
favourable water relations.
4
Table 3: Basic analytical data for rendzina on loess, with relict cambi horizon
Depth
Horizon
Soil reaction (pH)
CaCO3
Humus
Clay
The texture
cm
in the
%
%
%
of
the ground
water
KCl
0-5
A
7,2
6,6
0,8
3,36
2,9
Loam
5-37
C
7,9
7,0
1,1
0,80
8,0
Loam
37-65
C
8,2
7,0
0,8
0,57
10,0
Loam
65-100
II(B)
8,3
6,9
1,1
0,91
26,3
Loam
100-120
C
8,9
8,3
26,9
0,39
4,8
Loam
3. BASIC FEATURES OF AGRICULTURAL PRODUCTION IN THE ISLAND OF SUSAK
By the middle of the 18th century on Susak was present mixed economy: in the first place farming
(growing wheat, barley, beans, etc.), then wine growing with sheep farming and fishing. During the
period with this type of economy, the economic development of Susak was faster than the
development of Veli and Mali Lošinj, so that in 1650 the height of the tithe paid by Susak was 400
Venetian liras (as much as they paid and the Union), while Lošinj paid only 320 liras. A former
intensive farming evidenced by the size of a common guvna which was located on site of today's
large tank in the upper village, which is carried out grain. Later, in the late 18th and in the 19th
century, parallel to the economic success of Lošinj, on Susak comes to wine-growing and fishing
specialization, while farming and sheep breeding disappeared. Olive as a culture has never been
represented because of unsuitable soil. Agriculture of Susak is specific for several reasons: on the
island there is a working cattle (oxen, donkeys), there are no cars and plows, all works are carried out
by hand and hand-held tools, all transfer on the island is carried out by people who lives on it (men
on the back, women on their heads). As a basic tool, there is a square with a short-handled hoe
which digs the earth, grape-vines and which are held terraces of grape-vines, roads and gorges
(narrow passages cut in the sand).
Each man from Susak was entirely an individual entrepreneur, each was also a winegrower and
fisherman, sailor and acustomer. Their grapes, wines and salted fish was transported by the boat on
sails and oars (the first motor boat on Susak was in 1929) to Cres, Lošinj, and Istra as the nearest
mainland, where were individually sold or exchanged for other goods. Thus, 100 kg of grapes worded
6 kg of sheep cheese, 10 litters of olive oil, and 4 quintals of wood or 5 kg of wool.
Until the middle of the 19th century, on Susak were feudal relations because Susak, like the
neighbouring islands of Ilovik and the Unije was a feud of Osor and later Krk diocese. Residents of
Susak were therefore required to pay a third of the Osor diocese (in the 19th century a quarter) of all
in-kind yield, cereals, beans, then they have to pay to the church tithes of grain (intrada) for the
needs of the local church, head tax (the tax that was paid by the heads of families) and fish a
twentieth paid by all owners of netting. All this represented a great burden for otherwise poor island
(every third or fourth day residents of Susak worked for the bishop), so it is no surprise that the
church tax collectors were hated extremely by the people.
According to the rough data, today on the island are 26 hectares of vineyards, the complex of
cultivated grounds (lawns and gardens) on 25 hectares, predominantly agricultural land with
significant natural vegetation on 147 ha and transitional intensive healing of the natural vegetation
on 184 ha.
5