Global agriculture and water use (ha x 106)
Best practices on irrigation
q Cultivated area (rainfed + irrigated) = 1,500
q Irrigated area = 300 (20%)
Daniele Massa and Alberto Pardossi
Best practices in improving the
sustainability of agriculture
CRA-VIV
q Irrigated area for food production = 40%
q Irrigated area with salinity = 40%
EXPO Milan, 6 July 2015
Joint Research Centre and
Directorate-General for
Environment
[email protected]
<1700 m3/capita/year
<1000 m3/capita/year
The views expressed are purely those of the authors and may not in
any circumstances be regarded as stating an official position of the
European Commission. Neither the European Commission nor any
person action on behalf of the Commission is responsible for the use
which might be made of this presentation.
2/23
Water use efficiency (WUE)
70
1,200
Yield
q Seasonal/annual irrigation water use:
•
Field crops: 300 (e.g. beans) to 1200 mm (e.g. cotton)
•
Protected crops (per year): 600 (e.g. leafy vegs.) to 1500 (fruit vegs.)
•
Higher in soilless culture (open-loop hydroponics) than in soil
Irrigation volume
800
50
40
600
30
400
3
I (mm); Y (t/ha)
General aspects
60
WUE
WUE (kg/m )
1,000
20
200
10
q Tendency to over-irrigate (+10 to +50%) results in:
water loss
•
nutrient loss (with drainage water) and pollution (e.g. nitrates)
•
increased production costs (energy for pumping, fertilisers,…)
•
crop water stress (due to waterlogging and hypoxia in the root zone)
•
increased susceptibility to root diseases
F
0
-
•
Open field
Unheated
plastic
tunnel
Heated Heated soilless
Unheated
greenhouse greenhouse greenhouse
(closed cycle)
Irrigation management
& growing technology
1 mm = 1 L m-2 = 1 kg m-2 = 10 m3 ha-1
3/23
4/23
Approaches to efficient irrigation:
Deficit irrigation
Key elements of the BEMPs on irrigation
q Crop selection (species and cultivars)
DEFICIT
IRRIGATION
q Soil management (tillage, amendments, etc.)
q Water treatment and storage (desalinization, etc.)
q Deficit irrigation (partial root drying, regulated d.i. )
q Closed-loop irrigation systems (substrate culture)
Regulated deficit
Irrigation (RDI)
q Irrigation scheduling (ET models vs soil moisture sensors)
Partial root drying
(PRD)
q Irrigation systems (drip vs overhead irrigation)
http://www.pmsinstrument.com/winegrapes.htm
5/23
Deficit irrigation
6/23
Deficit irrigation
Net photosynthesis
100 80 60 40 -
Expansion
growth
-
-
-
-
-
-
-
-
-
20 -
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
Yleaf (-MPa)
7/23
8/23
Soilless-grown tomato: water and N balance)
(Tuscany; 2 crops/year; yield @ 25 kg/m2)
Approaches to efficient irrigation
Open vs closed irrigation systems
• Water = 6,950 m3/ha
Groundwater
Rainwater
• N = 1,330 kg (N)
• Water = 8,630 m3/ha
• N = 1,600 kg/ha (N)
Mixer
Sector 3
Sector 2
Raw water tank
Sector 1
Fertigation
strategy
Day-storage tank
Disinfection
unit
Drain water
• Water = 1,680 m3/ha
• N= 270 kg/ha N (17%)
Storage tank
Day-storage tank
21/70
9/23
Source: Incrocci, 2011
Soilless-grown tomato: water and N balance)
(Tuscany; 2 crops/year; yield @ 25 kg/m2)
• Water = 6,950 m3/ha
• N = 1,330 kg/ha (N)
10/23
Approaches to efficient irrigation
Irrigation scheduling
• Water = 6,950 m3/ha
• N = 1,330 kg (N)
•
Irrigation timers (the standard method?)
•
Determination of soil water balance (called ETbased method in greenhouse and nursery crops)
•
Direct measurement of moisture content in the
root zone with soil moisture sensors (SMS)
•
Integration of methods 2 and 3
•
Speaking-plant
• Water = 0 m3/ha
• N= 0 kg/ha N
11/23
12/23
1) Determination of available water in the root zone
Irrigation scheduling (dose and frequency)
Crop
Soil
Root
depth
Leaf area
indeX (LAI)
Water
Texture
Irr. system
Salinity
(EC)
Soil /substrate hydrology
I. efficiency
& uniformity
Air phase
100
Climate
Allowable
water deficit (AWD, mm)
% volume
Scheduling
hedu
Coefficient (KS)
80
60
40
20
10
14
56
20
ET (mm)
(mm
Dose = AWD · KS
So q
Soil
25
20
40
15
0
Soil
Easily Available
Water (EAW)
Unavailable
water (UW)
Solid phase
Soilless
Driving factor
Frequency (time)
Volume of media explored by the crop roots
§ Soil: 250 to 500 L m-2 (mm) depending on root depth
§ Soilless: 10 to 50 L m-2 (mm)
ET -based IS
RZS –based IS
Dose (mm)
14¤47
14/23
13/23
1) Determination of available water in the root zone
2.1) ET model: FAO equation.
100
(http://www.fao.org/docrep/x0490e/x0490e00.htm)
90
Air capacity
80
Volume (%)
2) Determination of the evapotranspiration rate
ET = kc · ET0
AIR
70
60
Kc: crop coefficient (ET/ETP). It incorporates crop
characteristics and averaged effects of soil evaporation.
Easily
available
water
50
30
20
ET0: reference or potential ET. It is assessed with
evaporation pan or based on weather conditions.
Total
available
water
40
WATER
10
SOLID FASE
0
SUBSTRATE
SOIL
0
10
300
20
30
40
50
60
70
80
90 100
1,000
15,000
Tension (hPa = cm of H2O)
15/23
16/23
2) Determination of the evapotranspiration rate
2) Determination of the evapotranspiration rate
2.2) ET model: plant transpiration under greenhouse.
2.2) ET model: semplified model for greenhouse.
P-M equation
Simplified equation
0.5
0.4
Y = 0.974 X - 0.001
R2 = 0.936
SEE = 0.023 kg m-2 h-1
MAPE = 15.9%%
Predicted values (Ed, kg m-2 h-1)
• ET is mostly determined by leaf transpiration (T)
• T depends basically on leaf area (LAI), the intercepted radiation (Ic), air
temperature and relative humidity, which both determine the vapour pressure
deficit (VPD)
• Stomata regulation of leaf T is often limited (due to poor gh. ventilation)
Predicted values (Ed, kg m-2 h-1)
0.5
0.3
0.2
0.1
0.0
0.0
0.1
0.2
0.3
0.4
-2
0.5
0.4
Y = 0.957 X + 0.002
R2 = 0.939
SEE = 0.022 kg m-2 h-1
MAPE = 15.5%%
0.3
0.2
0.1
0.0
0.0
0.1
0.2
0.3
0.4
0.5
Measured values (Ed, kg m-2 h-1)
-1
Measured values (Ed, kg m h )
Relationship between simulated and measured values of diurnal transpiration (Ed) in greenhouse
gerbera grown in substrate culture in different seasons (autumn, filled symbols; spring, empty
symbols). Transpiration was simulated using the Penman-Monteith equation or its simplified version
(regression model). (Carmassi et al., 2013)
I
T = A × c + B × LAI × VPD
l
18/23
17/23
DIRECT MESUREMENT OF SOIL
MOISTURE
WATER BALANCE
PLANT GROWTH
3) Direct measurement of water-related
parameters in the root zone
DATALOGGERS
CLIMATE
PARAMETERS
TDR
(Time Domain
Reflectometry)
IRRIGATION
RIGATI
SYSTEM
MANAGEMENT
FDR
(Frequency Domain
Reflectometry)
19/23
20/23
Approaches to efficient irrigation
Conclusions on BEMPs
Irrigation systems: drip vs overhead irrigation
Why?
q Irrigation is generally inefficient due to: empiricism in irrigation scheduling,
use of saline water (large leaching fraction), etc.
q Over-irrigation causes pollution due to the leaching of agrochemicals (e.g.
nitrates, phosphates, plant protection products), soil erosion, etc.
What?
q Advanced irrigation management (application of crop modelling and/or
sensing technology, deficit irrigation)
q Reuse of drainage water (closed system)
q Use of drip irrigation
q Other measures (crop selection, water treatment)
www.fao.org
www.wikipedia.com
Up to ≈ 100%
distribution efficiency
….especially
21/23
Thank you!
European Commission: Joint Research Centre and
Directorate-General for Environment
Email: [email protected]
Websites:
http://susproc.jrc.ec.europa.eu/activities/emas/
http://ec.europa.eu/environment/emas/index_en.htm
How?
q Regulations
q Dissemination of best practices
q Education and training
22/23