inforct: simulation tool for ca based rice-wheat systems. yashpal saharawat

InfoRCT: Simulation Tool for Conservation Agriculture based Rice-

Wheat Systems

Y.S. Saharawat

International Rice Research Institute [email protected]

Challenges Facing the R-W System

Challenges Facing the R-W System

Growing cereal demand vis-à-vis declining harvest area.

Declining/stagnating productivity.

Degrading soil and water resource base.

Inefficiency associated with intensive tillage.

Adverse changes in micro-climate.

Inefficient nutrient management.

Growing labor shortage

Escalating fuel price.

Growing cereal demand vis-à-vis declining harvest area.

Declining/stagnating productivity.

Degrading soil and water resource base.

Inefficiency associated with intensive tillage.

Adverse changes in micro-climate.

Inefficient nutrient management.

Growing labor shortage

Escalating fuel price.

Various Conservation Agriculture based resource conservation technologies (RCTs) are believed to be resource use efficient, environment-friendly and economically superior to conventional practices.

However, an accurate accounting of the ecology and economics of such practices is lacking.

A decision support system (DSS) is required to quantify the input-output budget, fluxes of N, and global warming potential (GWP) along with detailed cost/benefit analysis of the prominent RCTs in rice-wheat systems.

Introduction

Tillage

Conventional

Unpuddled Raised bed Zero-tillage

CA based Resource conservation technologies in rice-wheat systems

Crop establishment

Transplanting Direct-drill-seeding

Quantitative Evaluation of CA based RCTsQuantitative Evaluation of CA based RCTs

Productivity

Resource use efficiency

Cost effectiveness

Environmental impact

N loss

Greenhouse gas emission

Biocide residue

InfoRCT Decision Support System (DSS): The Concept

InfoRCT Decision Support System (DSS): The Concept

The DSS integrates bio-physical, agronomic and socio-economic parameters to establish empirical input-output relationships related to water, fertilizer, labour and biocide uses, GHG emissions, biocide residue in soil and N fluxes in rice-wheat system.

This is programmed in Microsoft Excel and inputs and outputs are calculated on a seasonal basis using the target-oriented-approach.

With this an optimal combination of inputs is identified to realize a target yield based on the biophysical environment and the production technique.

Outputs like GHG emissions, N losses, and biocide residue are then calculated based on the amount of input used and the related soil-plant processes.

Pathak et al. 2006

Target yield

Nutrient requirement

Waterrequirement

Manure/residue

Soil supply

Fertilizers

Irrigation

Potential evapo-transpiration

DepositionPrecipitation

Soil organic C

Global warming potential

Technology

Manure/residues

Root exudates

Fertilizer N

Seed

Machine

Human labor

Animal labor

Biocides

Legends:

NH3

volatilizationDenitrifi

cationNO3

leaching

CH4

emission CO2

emission N2O

emission Biocide residue

Schematic overview of the InfoRCT decision support system

OutputsModel inputs

Factors

Saharawat et al. 2011

Methane, nitrous oxide and carbon dioxide emissions

Soil + organic/inorganic inputs +

Technology

~ SOC ~ bulk_density~ soil_depth ~ crop_duration

~ cont. flooding ~ midseason drying ~ alternate flooding ~ zero tillage

~ fertilizer ~ root biomass ~ manure ~ residues

Saharawat et al. 2011, Pathak et al. 2011

Global Warming Potential

GWP = CH4 * 21 + N2O * 296 +

CO2 * 44/12

Biocide residue index (BRI)

BRI = Chemical use (g ha-1) * Toxicity index * Persistence index/100

<100 = Safe

100-200 =Permissible

>200 = Unsafe

Development and Calibration of

InfoRCT

Treatments in the Modipuram Experiment

Gathala et al. 2011 (a,b)

0

2

4

6

0 2 4 6

Observed yield (Mg ha-1)

Cac

ulat

ed y

ield

(Mg

ha-1

) Modi 2003

Modi 2004

Modi 2005

Wheat

Simulated and observed yields of rice and wheat in Modipuram

0

2

4

6

8

10

0 2 4 6 8 10

Observed yield (Mg ha-1)

Cac

ulat

ed y

ield

(M

g ha-1

)

Modi 2003

Modi 2004

Modi 2005

Rice


Sensitivity analysis of the InfoRCT


Technology Yield Total cost Net return Return compared

(Mg ha-1) (US $ ha-1) (US $ ha-1) with TP1TP1 12.2 1137 482 1.00TP2 12.0 1002 607 1.26TP3 9.8 901 428 0.89TP4 10.8 1012 435 0.90TP5 11.1 910 572 1.19TP6 11.6 1014 540 1.12

Yield of rice is more with puddled transplanting (TP1) but net returns are higher with midseason drying (TP2) and double zero-till systems (TP5 and TP6) due to reduced cost of irrigation in the former and reduced cost of tillage in the latter.

Simulated yield and income in different RCTs


0

1000

2000

3000

4000

TP1 TP2 TP3 TP4 TP5 TP6

GW

P (

kg

CO 2

eq

ui.

ha-1

) Rice Wheat

Calculated GWP is more in the conventional system because of more methane emission in continuously submerged condition in rice and more fuel consumption for tillage and irrigation.

GWP in different RCTs in Modipuram

Pathak et al. 2011

Biocide residue index in rice and wheat under different technologies in rice-wheat

system

0

50

100

150

200

250

TP1 TP2 TP3 TP4 TP5 TP6

Bio

cid

e re

sid

ue

ind

ex

WheatRice

Biocide residue index is at a safe limit in the puddled transplanted systems, whereas it exceeds the safe limit in direct drill-seeded and raised bed systems because of more herbicide use

Biocide residue index (BRI) in different RCTs

Pathak et al. 2011

Validation and

Evaluation of

InfoRCT at farmers’

fields

Study site

Study siteStudy site

India

Haryana

Experimental site 10 Villages at Haryana, India 76 Farmers

Survey methodology Social, economic and educational

status Input use: seed, irrigation, tractor,

labour, fertilizer, and pesticides use Output: Grain and straw yield

Simulation InfoRCT- for estimation of global

warming potential

MethodologyMethodology

Rice yield under alternative tillage and crop establishment methods

o No significant differences in rice yield between conventional tillage/CE and alternative tillage/CE.

o Aromatic rice (Basmati) had lower yield due to low genetic yield potential.

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

CTPR UPTPR CTPR BTPR CTPR DSR CTPR ZT TPR

Yie

ld (

Mg/h

a)


Economics

Conventional Alternate tillage Difference

Total Cost (US$) 518 379-473 45-139

Net income (US$) 275 345-377 70-102

fixed cost1%Seed

2%

Transplanting5%

Threshing5%

Harvest7%

Weedicide/ insecticide7%

Land preparation37%

Irrigation22%

Fertilizers14%

11

Input cost in conventional tillage/CE

Saving in alternate tillage and CE

Labour8%

Land preparation

77%

Irrigation water15%

Labour 22%


Simulated and observed net income in different tillage and crop establishment methods

y = 0.99x + 3.68

R2 = 0.95

0

100

200

300

400

500

600

700

800

0 100 200 300 400 500 600 700

Observed net income (US $)

Sim

ula

ted

ne

t in

co

me

(U

S $

)


Technology

Crop CH4 soil N2O soil N2O fertilizer

CO2 machine

CO2 fertilizer

prod.

CO2 biocide prod.

CO2 fertilizer

appli.

CO2 biocide appli.

GWP (CO2 equi.)

kg ha-1 kg N ha-

1

kg N ha-

1

kg C ha-

1

kg C ha-

1

kg C ha-

1

kg C ha-

1

kg C ha-

1

kg ha-1

T1 Rice 59 0.10 0.32 478 199 47 11 11 3286Wheat 0 0.10 0.42 81 256 0.2 14 0 597RW 59 0.20 0.74 559 455 47 25 11 3884

T2 Rice 48 0.11 0.36 507 197 47 10 11 3174Wheat 0 0.11 0.47 66 256 0 14 0 576RW 48 0.23 0.83 573 454 47 24 11 3750

T3 Rice 25 0.12 0.24 389 117 82 6 18 2209Wheat 0 0.12 0.53 60 261 0 14 0 591RW 25 0.24 0.77 450 378 82 19 18 2799

T4 Rice 25 0.12 0.37 446 182 69 9 15 2491Wheat 0 0.12 0.46 59 222 0 11 0 542RW 25 0.24 0.83 505 404 70 21 15 3033

T5 Rice 25 0.12 0.41 433 202 82 10 18 2482Wheat 0 0.12 0.54 58 222 0 10 0 564RW 25 0.24 0.95 501 466 82 25 18 3046

Simulated greenhouse gas emissions in rice-wheat system with different tillage and crop establishment practices


Conclusions

Double no-till rice-wheat system increases farm income; saves water, labour and energy; and reduces global warming potential.

The technology could be a viable alternative for the conventional puddled transplanted rice- and intensive tilled-wheat system.

The InfoRCT decision support system could capture the major effects of tillage and crop management practices and could be used for a comparative assessment of different resource conservation technologies in rice-wheat system.

Technologya Crop Input Output

Fertilizer

Irrigation

Rain Fixation Uptake Leaching

Volatilization

Denitrification

Total loss

kg N ha-1

TP1 Rice 153 12 3 25 108 19 33 26 79

Wheat 173 1 1 5 113 11 31 4 46

RW 326 13 4 30 221 30 64 31 125

TP2 Rice 138 10 3 25 101 18 31 24 73

Wheat 188 1 1 5 121 11 34 5 49

RW 326 11 4 30 222 29 64 29 122

TP3 Rice 71 8 3 25 72 9 20 16 45

Wheat 176 1 1 5 114 9 32 4 45

RW 247 9 4 30 186 18 52 20 90

TP4 Rice 107 10 3 25 88 14 26 21 60

Wheat 171 1 1 5 112 9 31 4 44

RW 278 11 4 30 200 22 57 25 104

TP5 Rice 114 8 3 25 90 15 26 21 63

Wheat 178 1 1 5 116 10 32 4 47

RW 292 9 4 30 205 25 59 26 110

TP6 Rice 120 10 3 25 93 15 28 22 65

Wheat 191 1 1 5 122 11 34 5 50

RW 310 11 4 30 215 26 62 27 115

Calculated input, uptake and losses of N in rice-wheat system with different technologies in

Modipuram

• Midseason drying and double zero-till systems increased income whereas raised bed systems decreased it compared with the conventional system.

• Direct-seeding and double zero systems reduce GWP but have a risk of high biocide residue. More efficient and safer herbicides, therefore, need to be developed.

• The InfoRCT decision support system could be used for a comparative assessment of different RCTs for productivity, income and environmental impact at different scenarios of soil, climate and crop management.

Conclusions

Diffusion of zero tillage in wheat in the IGP

Diffusion of zero tillage in wheat in the IGP

0.0

0.5

1.0

1.5

2.0

2.5

Are

a un

der z

ero-

tilla

ge

(mill

ion

ha)

Mechanistic Model vs. Decision Support Tool

Parameter Mechanistic model (DNDC)

Decision Support Tool (InfoRCT)

Overall purpose

Computation of actual pools and fluxes

Comparison of technologies for yield, net income, N balance and GHG emission

Scale Plot Farm

Basic concept Description of processes through algorithms and empirical data

Description of processes through empirical data and algorithms

Programming C++ MS Excel

Inputs Detailed soil, climatic and management data

Basic soil, climate, management, and prices data

Outputs C and N budget (daily records)

C and N budget (seasonal records)

Socio-economic parameters

Indirect: Yields Direct: Net income

o Higher GWP in the conventional system was due to more fuel use for tillage, water pumping and more methane emission in submerged condition.

o At the current price of C credit (US$ 30 Mg-1 CO2) double no till system fetches an additional income of US$ 24 ha-1 compared to the conventional rice-wheat system.

Simulated global warming potential

1697

1514

1742

2400

1616

0

500

1000

1500

2000

2500

CTPR-CW UTPR-ZTW BTPR-Bed DSR-ZTW ZT TPR-ZTW

Co 2

(kg/h

a)

CTPR-CW UTPR-ZTW BTPR-Bed DSR-ZTW ZT TPR-ZTW

Monthly total rainfall, mean maximum and minimum temperatures and mean solar radiation

in Modipuram

00

05

10

15

20

25

30

35

40

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Tota

l ra

infa

ll (

mm

)

00

05

10

15

20

25

30

Tem

per

atu

re (

o C)

an

d s

ola

r ra

dia

tion

(M

J m

-2 d

-1)

RainfallMax. temp.Min. temp.Solar radiation

Technologies Adopted by FarmersTechnologies Adopted by Farmers

Treatment Rice Wheat Number of

farmers

T1 Transplanted rice after

conventional puddling

(FP),

Broadcasted wheat after

Conventional tillage (FP)

76

T2 Transplanted rice in

unpuddled fields (UP-TPR)

Drill sown wheat after zero

tillage (ZTW)

41

T3 Transplanted rice on raised

beds (BP-TPR)

Drill sown wheat on same

beds after reshaping (ZTW)

9

T4 Transplanted rice after

zero tillage (ZT-TPR)


tillage (ZTW)

6

T5 Direct-drill-seeded rice

after zero tillage (DSR)


tillage (ZTW)

20

Monthly total rainfall, mean maximum and minimum temperatures and mean sunshine hour

in Haryana

00

05

10

15

20

25

30

35

40

45

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Tot

al r

ainf

all (

mm

)

00

50

100

150

200

250

Ave

rage

tem

p. (

o C) a

nd s

unsh

ine

(hr d

-1)

Rainfall

Max. temp.

Min. temp.

Sunshine hours

inforct: simulation tool for ca based rice-wheat systems. yashpal saharawat

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