Jun 28, 2012 - Llanos de Vicar. Balanegra. Balerma. Puebla de Vicar. San Agustin. Cortijos de Marin. Santa Maria del Aguila. Santo Domingo. San Silvestre.
Nitrate leaching losses from a recently developed intensive horticultural system in a previously disadvantaged region R.B. Thompson1, M.R. Granados2, J.C. Gazquez2, J.S. Rodríguez-López1, M.D. Fernandez2, M.G. Gallardo1, C. Martínez-Gaitan1, C. Gimenez3 1 Dpto. Producción Vegetal, Universidad de Almería, 04120 La Cañada, Almería, Spain. 2Cajamar Estación Experimental “Las Palmerillas”, Apdo. 250, 04080 Almería, Spain. 3Dpto. Agronomía, Universidad de Córdoba, 14080 Córdoba, Spain Background Objectives
To measure and characterise NO3- leaching from this system from: (a) “open” hydroponic crops, and (b) cropping sequences in soil
Greenhouse-based vegetable production in Almeria, Spain • 27,000 ha simple plastic greenhouses; 10,000 ha more in adjoining provinces • 80% cropping in soil; 20% in “open” hydroponic systems • System has developed in last 30 years; responsible for local economic miracle • Was very poor region; now has highest per capita income in Spain • Aquifers have massive nitrate contamination (see Fig 1) • Considerable interest in copying this system in numerous other countries de
la
Cueva
Barranco
-9 02 4 AL
la
de
AL-108
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Llanos de Vicar
867
-1 02 AL
13 -90 AL
8 AL-900
2 -10 AL
del
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Cortijos de Marin
766
Las Marinas
Nitratos (mg/l)
AL-10 5
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AL-9 009
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El Solanillo A-389
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262 jib e
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AL
Las Norias de Daza
623 627
546
Matagorda
del
AL-9024
526 610
529 534
La Mojonera
la mb Ra
298
de
de l
4
117 Balerma
9
9 902 AL-
AL-108
509 507 518
-10 AL
del
de
Balanegra
68
(E-15)
San Silvestre
705
600
Santo Domingo
402 412
300
Al
596
AL-9024
142
394
75
Sard ina
s ecela Alm
de AL-400
Tarambana
Balanegra
N-340
Santa Maria del Aguila 379 500
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EU Limit: 0.8 mM
Fig. 1
EU Limit
48 36
MA
2000m 4000m
NO3-
38
50
Salinas de Cerrillos
sa
MA
0m
74
0
concentration (mM) in superficial aquifer
m a y-8 6
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m a y- 8 7 m a y-8 8 m a y- 8 9 m a y- 9 0
o ct- 91
o ct-9 2
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Fig. 2 NO3- concentration (mM) in one well with time
Materials & methods General: • Crops grown in plastic greenhouses in Almería • Management consistent with local practice • Complete nutrient solutions (10-14 mM NO3-, 1.0-1.5 mM NH4+) in most irrigations • Drainage collected daily, and analysed for NO3- and NH4+
Cropping sequences in soil • Drainage collected in free-draining, re-packed lysimeters (2 x 4 x 0.7 m deep), two reps. • Irrigation manage. with tensiometers (-15 - –35 kPa) after establishment • Clay loam texture 1) manure (1,200 kg N ha-1) on 10 Jun.03, 40 mm water (30 Jun.03), curtailed pepper (25 Jul. to 22 Aug.03), pepper (27 Sep.03 to 2 Jan.04), 80 mm irrigation to leach salts (9 Jan.04) 2) chemical disinfection (20&27 Jul.04), curtailed tomato (25 to 30 Aug.04), tomato (27 Sep.04 to 2 Mar.05). Only H2O applied to 13 Oct.04
“Open” hydroponic crops • Drainage collected in trays, each with 2 x 40 L substrate bags, and 6 plants per bag. 1) Pepper grown in perlite (21 Jul.04 to 6 Jan.05) , drainage in two trays 2) Tomato grown in rockwool (6 Mar. to 6 Jul.05), drainage in four trays
Results
200 0 22-Jul
25 20
20-Sep
19-Nov
18-Jan
Nutrient solution Drainage
15 10
EU limit: 0.8 mM 5 22-Jul
20-Sep
Pepper grown in perlite:
19-Nov
18-Jan
400
Irrigation/Nutrient Solution Drainage
300 200 100 0 28-Jun
12-Aug
20
26-Sep
10-Nov
25-Dec
Irrigation/Nutrient Solution
16
Drainage
12 8 4 0 28-Jun
EU limit: 0.8 mM 12-Aug
26-Sep
10-Nov
25-Dec
Irrigation & D rainage (m m )
400
Drainage
500
Tomato in soil cropping sequence
400 300
Irrigation/Nutrient Solution Drainage
200 100 0 17-Jul
N itrate co ncen tratio n (m M )
Irrigation/Nutrient Solution
Irrigation & D rainage (m m )
600
Pepper in soil cropping sequence
N itrate concen tration (m M )
N itra te c onc entration (m M )
Irrig atio n & D rainag e (m m )
Pepper grown in perlite
31-Aug
15-Oct
29-Nov
13-Jan
27-Feb
30 25 20
Irrigation/Nutrient Solution Drainage
15 10 5 0 17-Jul
EU limit: 0.8 mM 31-Aug
15-Oct
29-Nov
13-Jan
27-Feb
452 kg NO3--N ha-1 lost in drainage, from 950 kg N applied ha-1 (93% as NO3-); average NO3- concentration of 995 mg NO3- L-1; 201 mm of drainage, from 526 mm of irrigation, i.e. 38% drainage fraction
Tomato grown in rockwool: 162 kg NO3--N ha-1 lost in drainage, from 555 kg N applied ha-1 (94% as NO3-); average NO3- concentration of 944 mg NO3- L-1 76 mm of drainage from 316 mm of irrigation, i.e. 24% drainage fraction Cropping sequences in soil:Substancial drainage associated with (a) crop establishment and (b) large soil management irrigations e.g. soil (chemical) disinfection and salt leaching Drainage water generally had >6 mM NO3- (>370 mg NO3- L-1), even when only water applied
Discussion Point: Given that this agricultural system is largely responsible for rapidly enriching this region, it will be extremely difficult to introduce “restrictive” crop management practices that effectively reduce the massive NO3- contamination that is occurring. This has implications for disadvantaged regions where intensive horticultural systems are currently being introduced.
