Best practices on irrigation

jrc-ipts-emas@ec.europa.eu

Joint Research Centre and Directorate-General for

Environment

Best practices in improving the

sustainability of agriculture

EXPO Milan, 6 July 2015

Daniele Massa and Alberto Pardossi

CRA-VIV

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.

Global agriculture and water use (ha x 106)

q Cultivated area (rainfed + irrigated) = 1,500

q Irrigated area = 300 (20%)

q Irrigated area for food production = 40%

q Irrigated area with salinity = 40%

<1700 m3/capita/year

<1000 m3/capita/year

2/23

General aspects

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

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

1 mm = 1 L m-2 = 1 kg m-2 = 10 m3 ha-1

F 3/23

Water use efficiency (WUE)

0

10

20

30

40

50

60

70

WU

E (

kg

/m

3)

-

200

400

600

800

1,000

1,200

Open field Unheated plastic tunnel

Unheated greenhouse

Heated greenhouse

Heated soilless greenhouse

(closed cycle)I

(mm

); Y

(t/

ha

)

Yield

WUE

Irrigation volume

Irrigation management

& growing technology

4/23

Key elements of the BEMPs on irrigation

q Crop selection (species and cultivars)

q Soil management (tillage, amendments, etc.)

q Water treatment and storage (desalinization, etc.)

qDeficit irrigation (partial root drying, regulated d.i. )

qClosed-loop irrigation systems (substrate culture)

q Irrigation scheduling (ET models vs soil moisture sensors)

q Irrigation systems (drip vs overhead irrigation)

5/23

Approaches to efficient irrigation: Deficit irrigation

DEFICIT

IRRIGATION

Regulated deficit

Irrigation (RDI)

Partial root drying

(PRD)

http://www.pmsinstrument.com/winegrapes.htm

6/23

Deficit irrigation

7/23

Deficit irrigation

100 -

80 -

60 -

40 -

20 -

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

- - - - - - - - -

Yleaf (-MPa)

Expansion

growth

Net photosynthesis

8/23

Approaches to efficient irrigation Open vs closed irrigation systems

RainwaterGroundwater

Day-storage tankStorage tank

Drain water

Raw water tank

Mixer

Sector 1

Sector 3

Sector 2

Disinfectionunit

Fertigation

strategyDay-storage tank

21/70 9/23

Soilless-grown tomato: water and N balance) (Tuscany; 2 crops/year; yield @ 25 kg/m2)

• Water = 6,950 m3/ha

• N = 1,330 kg (N) • Water = 8,630 m3/ha

• N = 1,600 kg/ha (N)

• Water = 1,680 m3/ha

• N= 270 kg/ha N (17%)

Source: Incrocci, 2011 10/23

Soilless-grown tomato: water and N balance) (Tuscany; 2 crops/year; yield @ 25 kg/m2)

• Water = 6,950 m3/ha

• N = 1,330 kg (N) • Water = 6,950 m3/ha

• N = 1,330 kg/ha (N)

• Water = 0 m3/ha

• N= 0 kg/ha N

11/23

Approaches to efficient irrigation

Irrigation scheduling

• Irrigation timers (the standard method?)

• Determination of soil water balance (called ET-

based 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

12/23

Irrigation scheduling (dose and frequency)

Soil q So

Scheduling

Coefficient (KS)

Soil qET (mm)

Allowable

water deficit (AWD, mm)

Driving factor

ET - based IS

RZS –based IS

Dose = AWD · KS

Leaf area

indeX (LAI)

Root

depth

Salinity

(EC)

Texture I. efficiency

& uniformity

ET (mm

hedu

Water Crop Soil Irr. system

Climate

Frequency (time) Dose (mm)

13/23

1) Determination of available water in the root zone

Soil /substrate hydrology

0

20

40

60

80

100

Soil Soilless

56

15

14

40

10 20

20 25

Air phase

Easily Available

Water (EAW)

Unavailable

water (UW)

Solid phase

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)

% v

olu

me

14¤47

14/23

0 10 20 30 40 50 60 70 80 90 100

0

10

20

30

40

50

60

70

80

90

100

SOLID FASE

WATER

Air capacity

Easily available

water Total

available water V

olu

me

(%

)

Tension (hPa = cm of H2O)

AIR

300 1,000

SUBSTRATE

SOIL 15,000

15/23

1) Determination of available water in the root zone

2) Determination of the evapotranspiration rate

2.1) ET model: FAO equation.

(http://www.fao.org/docrep/x0490e/x0490e00.htm)

ET = kc · ET0

Kc: crop coefficient (ET/ETP). It incorporates crop

characteristics and averaged effects of soil evaporation.

ET0: reference or potential ET. It is assessed with

evaporation pan or based on weather conditions.

16/23

2) Determination of the evapotranspiration rate

2.2) ET model: plant transpiration under greenhouse.

• 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)

VPDLAIBcI

AT ××+×=l

17/23

2) Determination of the evapotranspiration rate

2.2) ET model: semplified model for greenhouse.

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)

0.0 0.1 0.2 0.3 0.4 0.50.0

0.1

0.2

0.3

0.4

0.5Y = 0.974 X - 0.001

R2

= 0.936

SEE = 0.023 kg m-2

h-1

MAPE = 15.9%%

Measured values (Ed, kg m-2

h-1

)

Pre

dic

ted v

alu

es (

Ed,kg

m-2

h-1

)

0.0 0.1 0.2 0.3 0.4 0.50.0

0.1

0.2

0.3

0.4

0.5Y = 0.957 X + 0.002

R2

= 0.939

SEE = 0.022 kg m-2

h-1

MAPE = 15.5%%

Measured values (Ed, kg m-2

h-1

)

Pre

dic

ted v

alu

es (

Ed,kg

m-2

h-1

)

P-M equation Simplified equation

18/23

3) Direct measurement of water-related parameters in the root zone

TDR

(Time Domain Reflectometry)

FDR

(Frequency Domain Reflectometry)

19/23

DIRECT MESUREMENT OF SOIL

MOISTURE DATALOGGERS

WATER BALANCE

PLANT GROWTH

IRRIGATION

SYSTEM

MANAGEMENT

RIGATI

CLIMATE

PARAMETERS

20/23

Approaches to efficient irrigation

Irrigation systems: drip vs overhead irrigation

www.wikipedia.com

Up to ≈ 100% distribution efficiency

www.fao.org

….especially

21/23

Conclusions on BEMPs

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)

22/23

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.

How?

q Regulations

q Dissemination of best practices

q Education and training

Thank you!

European Commission: Joint Research Centre and

Directorate-General for Environment

Email: jrc-ipts-emas@ec.europa.eu

Websites:

http://susproc.jrc.ec.europa.eu/activities/emas/

http://ec.europa.eu/environment/emas/index_en.htm