Tradeoffs in land and water productivity of rice with

establishment method and irrigation schedule

Sudhir Yadav and Liz Humphreys

Outline

• Establishment method of rice• Performance of DSR and AWD

field experiment Model simulation

•Conclusion•Research need

Rice agriculture is the engine of growth for rural and urban

economies…and maintaining peace

Conventional practice of growing RiceNursery raising

Puddling

Transplanting

Issues and Concerns• Labour cost and availability• Ground water depletion/deterioration • Energy requirement to pump groundwater• Productivity of rice• Soil and environmental health

*Some of these problems can be handled by changing establishment method of rice

Other practices of establishing Rice

Establishment method of rice

Transplanting

Puddled

Manual

Mechanical

Unpuddled

After dry Tillage

After Zero Tillage

Direct seeding

Wet seeding

Puddled field

Broadcasting

Line sowing

Unpuddled field

Broadcasting

Line sowing

Dry seeding

After dry tillage

After Zero tillage (+M/-

M)

Direct seeding

Mechanical transplanting, WSR & DSR• labour saving - reduced costs

- timely establishment

DSR• beneficial to non-rice crops in the rotation (e.g. wheat & maize) due to avoidance of puddling = improved soil)• opportunity to introduce conservation agriculture

in rice – upland rotations e.g. rice-wheat(zero tillage, surface residue retention = mulch)

Drivers of different establishment method

-40

-30

-20

-10

0

10

20

30

40

Prod

uctiv

ity in

dex

of D

SR

Performance of DSR in IGP

DSR is considered as a “water saving technology” but the fact is- it is just an “establishment method”

0

2

4

6

8

0 500 1000 1500 2000 2500 3000

Yield (t ha-1)

Water input (mm)

Increasing “drying period"

IRRIGATION+ RAIN

Adapted from Bouman & Tuong 2001

Rice is very sensitive to water deficit

11Ladha et al. (2000)

Irrigated rice & wheatRainfed rice, partially irrigated wheat

Punjab: “Food basket of India”

2009

0

2

4

6

8

10

PTR DSR

Yield (t/ha)

Daily 20 kPa 40 kPa 70 kPa

• Regardless of establishment method, rice very sensitive to soil drying

• With more water stress (>20 kPa), yield penalty was higher in DSR than PTR.

Water requirement of DSR vs puddled transplanted rice (PTR)Punjab, India (clay loam, deep watertable)

4 irrigation treatments - daily or soil water tension 20, 40 or 70 kPa at 15-20 cm

for potential, water-limited, and/or nitrogen-limited conditions (lowland, aerobic rice)Effects of weather, irrigation, nitrogen fertilizer, general management, variety characteristics, soil type (hydrological, native N supply)

version 2.0, 2004; and 2.13, 2009

Fully documented User-friendly interface (FSEWin) Tutorial available Standard evaluation methodology Standard data sets available www.knowledgebank.irri.org/oryza2000/

Oryza2000: a rice growth simulation model

Application of ORYZA• Calibration: from 2 year field experiment data• Evaluation: 4 irrigation regime each year• Simulation: 40 years (1970-2009) past weather

data of Ludhiana, India

Irrigation threshold• First 30 DAS: 2-d after disappearance of water• After 30 DAS: SWT based (10,20,..........70kPa)

Performance of ORYZA2000 to predict grain yield

Irrigation threshold

Gra

in y

ield

(kg

ha-1

)

Irrigation threshold

Gra

in y

ield

(kg

ha-1

)

Irrigation threshold

Gra

in y

ield

(kg

ha-1

)

Irrigation threshold

Gra

in y

ield

(kg

ha-1

)

PTR

DSR

2008

2008

2009

2009

Performance of ORYZA2000 to predict water balance components

Simulation with 40 years past weather data

Grain yield and IW input with different irrigation schedule

Irrigation threshold (kPa)

Gra

in y

ield

(kg

ha-1

)

Irrig

atio

n w

ater

(mm

)

PTR DSR

Irrigation threshold (kPa)

Eva

potra

nspi

ratio

n (m

m)

PTR DSR

Irrigation threshold (kPa)

Dra

inag

e (m

m)

Where is the water saving?

(Percolation+Seepage)

Can we count it under “water saving”

Safe AWD- PTR vs DSR

f(x) = 3.24 x − 424.3R² = 0.979335327149392

f(x) = 4.13519556091232 x − 396.092387772728R² = 0.975058114317446

PTR DSR

Day of year

Cum

ulat

ive

irrig

atio

n in

put (

mm

) Stage 1 Stage 2 Stage 3 y = 4.14x - 396.1R² = 0.97

y = 3.24x - 424.3R² = 0.98

Cracking in soil

SWT and Cracking intensity*

PTRDSR

Pro

porti

on a

rea

of c

rack

s (%

)

SW

T (k

Pa)

*measurement with WinDIAS Sofware

Water productivity: PTR vs DSR

PTRDSR

Irrigation threshold

WP

IW (g

kg-

1)

Irrigation threshold

WP

ET

(g k

g-1)

WP

I+R

(g k

g-1)

Target Technology Predicted outcome

Yield

(t ha-1)WPI

(g kg-1)

WPET

(g kg-1)

ET

mm

Maximizing yield DSR-CF 9.8 0.37 1.39 705

Maximizing WPI DSR-30 kPa 8.2 1.81 1.41 586

Maximizing WPET PTR-20 kPa 8.5 1.19 1.66 518

Minimizing ET PTR-60 kPa 7.2 1.30 1.45 497

Selection of establishment method and irrigation schedule

The biggest gains in irrigation water saving are from adoption of safe AWD (establishment method is of secondary importance)

Safe AWD • reduced runoff, percolation & seepage (no effect on

ET) (i.e. it will not make more water available for other uses where runoff & deep drainage can be used elsewhere)• reduced irrigation requirement for DSR by ~30%

compared with PTR in Punjab, India(needs to be evaluated in other situations)• requires ability to deliver water when needed (because of sensitivity of rice to soil drying)

Significance of above for irrigation system managers

• irrigation scheduling for DSR o can we reduce frequency of irrigation during some

crop stages & further reduce irrigation input without reducing yield?

o how is this affected by soil type, climate, varietal duration etc?

o develop farmer friendly techniques for AWD Field water tube (shallow water table) Tensiometer (deep water table)

• does adoption of zero tillage & mulching in a rice-upland cropping system increase total system yield, WPi & WP of depleted water?

• what are the real water savings at higher spatial scales (irrigation schemes, catchments, river basins)?

Research needs for AWD & DSR

Acknowledgement

• Gurjeet Gill, The University of Adelaide, Australia

• Liz Humphreys, International Rice Research Institute, Philippines

• Tao Li, International Rice Research Institute, Philippines

• S.S.Kukal, Punjab Agricultural University, India

Thank You !