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!