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Environmental
Sustainability of Vegetable
Production above a Shallow
Aquifer
Vesna Zupanc
University of Ljubljana, Slovenia FAO/IAEA International Symposium
on Managing Soils for Food Security and Climate Change Adaptation and Mitigation
23 – 27 July 2012 Vienna, Austria
IAEA-CN-191-59
City of Ljubljana
City of Ljubljana
• Capitol of Slovenia
– 300.000 inhabitants
• Fresh water supply
from groundwater
• Market for fresh
vegetables
Intensive vegetable production
on water protection areas
Intersection
of
interests:
• Urban area
• Agricultural land
• Environment –
water supply for
the city
Water protection areas (Ministry of Environment, 2005)
Land use
Decree on
the water protection zone
for the aquifer of Ljubljansko polje
Land use and water protection
areas on Ljubljana Field
Fertile arable land above
shallow aquifer
Very intensive agricultural
land use – vegetable
production Photos: http://www.life-income.si/landscape
Tectonic depression
Lithology of Ljubljana aquifer
Bračič Železnik et al, 2005
Major water
fluxes
of Ljubljana
aquifer
Constant recharge due to snow
melt from NW Alpine part
Vižintin, Souvent, Veselič, Čenčur - Curk,
2009, Journal of Hydrology 377: 261-
273
650
mm
ET
120
0
mm
P
Nature of the cover above
shallow aquifer
Gravelly layers with low retention capacity
High threat of nitrate leaching
Shallow groundwater level Photos: http://www.life-income.si/landscape
Dynamic capacity of
Ljubljana aquifer
is between 3 to 3.5 m3/s.
Challenges of vegetable
production on shallow aquifer • Stable yield
• Environmentally friendly
• Interchangeable climatic conditions:
– High temperatures in summer, drought on shallow, stony soils
– High precipitation events
Challenges of vegetable
production on shallow aquifer
• Under such conditions – shallow aquifers
are vulnerable to nitrate pollution
– high nitrogen fertilizer applications in the
intensive vegetable production areas
– urban and industrial pollution
Experiment - comparison of
farmer’s practice Treatments:
• Control no fertilisation, farmer’s irrigation practice
• Farmers broadcast fertilisation, irrigation once after planting
• 100% irrigation (fertigation)
Intensive vegetable production
on water protection areas
15N labelled fertiliser
NUCLEAR TECHNIQUES
Intensive vegetable production
on water protection areas
15N labelled fertiliser
NUCLEAR TECHNIQUES
Fertigation:
labelled KNO3 +unlabelled water soluble
Ca(NO3)2 in tap water solution
with final relative 15N concentration of
3.52±0.04 at.%.
Farmer’s practice
unlabelled Ca(NO3)2 (0.365 at.% 15N) was
broadcast,
application of the labelled fertiliser as a
solution.
Field experiment on
Ljubljana Field
- measurement tools
1 Environscan (FDR)
2 Trase (TDR)
3 soil water
sampling
4 groundwater
sampling
5 rain gauge (preciptation/farmer’s
irrigation control)
1 1
2
3
3
4
5 5
Results – water balance
Endive 2006 Cabbage 2007
(mm) Fertigation
Farmer's
practice Control Fertigation
Farmer's
practice Control
Rainfall 355 184
Irrigation
20
100
100
110
100
100
ETcrop 220 214 214 377 350 350
Results – nutrient balance
Endive 2006 Cabbage 2007
(kg ha-1 ) Fertigation
Farmer's
practice Control Fertigation
Farmer's
practice Control
Estimated
nitrate-N
losses 43 117 –6 –9 –13 –14
N input 79 80 0 200 200 0
Crop N
uptake 63a 69a 65a 169b 246a 84c
N balance –28 –6 –61 28 –24 –72
Nitrate in groundwater
19
21
23
25
27
29
31
33
35
23
. 5
. 0
6
31
. 8
. 0
6
9.
12
. 0
6
19
. 3
. 0
7
27
. 6
. 0
7
5.
10
. 0
7
13
. 1
. 0
8
22
. 4
. 0
8
Nit
rate
Co
nce
ntr
atio
n (
mg
/l)
V-1 V-2 V-3 V-4 V-5
Groundwater level
264
265
266
267
23. 5. 06
31. 8. 06
9. 12. 06
19. 3. 07
27. 6. 07
5. 10. 07
13. 1. 08
22. 4. 08
Gro
un
dw
ate
r le
ve
r (m
)
V1 V2 V3 V4 V5
Ground
level
273 m asl
Results
fertigation and control treatment had the lowest
15N atom % excess
lowest N leaching deriving directly from added
fertiliser (autumn and winter)
0
20
40
60
80
100
120
18 33 48 11 26 41
2006
Pre
cip
ita
tio
n (
mm
)
-3
-2
-1
0
1
2
15N
at
% e
xc
es
s
Precipitation weekly Fertigation Farmer's practice Control
2007
endive cabbage
Yield
cabbage
2007
0
20
40
60
80
100
120
Fertigation Farmer's
practice
Control
Yield (t/ha)
Yield Best results with farmer’s practice
Šturm, Kacjan-Maršić, Zupanc, Bračič-Železnik, Lojen, Pintar, 2010. Sci. Hort. –
Amsterdam. 125 (2), 103-109
Zupanc, Šturm, Lojen, Maršić-Kacjan, Adu-Gyamfi, Bračič-Železnik, Urbanc,
Pintar, 2011. Agric. Ecosys. Envir. 144 (1) 167-174
Conclusions
• With the help of nuclear techniques we
were able to identify environmentally
friendly techniques, that potentially require
more time and money – to successfully
implement them in practice – possible
through legislation, financial endorsement
and education
Conclusions
• Direct results represent guidelines for
fertigation in the production of vegetables
with a shorter growing period (i.e. lettuce and
Brassicaceae), grown on areas where potentially
high groundwater pollution is possible due to the
soil structure.
• Fertigation, as an environmentally friendly
practice, should therefore be considered for
vegetable production.
Cooperation with:
Slovenian Research Agency (ARRS) L1-7097 (C) Nitrate migration in a plant-soil-groundwater system
Applied Research Project
Jože Janež, Sneberje, farmer
IAEA Protecting Groundwater and Soil against Pollutants Using Nuclear Techniques TC project
SLO/5/002
Working team on the
research project
Martina Šturm, Sonja Lojen, Institute Jožef Stefan, Department of Environmental Sciences
Janko Urbanc, Geological survey of Slovenia
Branka Železnik Bračič, Drinking water and Sewerage System Public Utility
Joseph Adu-Gyamfi, Soil Science Unit, IAEA, Vienna, Austria
Marina Pintar, Peter Korpar, Vesna Zupanc, Biotechnical Faculty Ljubljana, Agronomy Department
Thank you for your attention!
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