Agronomic and environmental evaluation of a new approach for water-saving ground

cover rice production system (GCRPS)

S Lin1 、 K. Dittert2 、 HB Tao1 、 KR Shen3 、 YC

Xu4 、 SW Gao4 、 XL Fan5 、 MS Fan1 、 SH Lu6 、 LH Wu7 、FS Zhang1

1China Agriculture University, 2University of Kiel, 3Agricultural Bureau Hubei, 4Nanjing Agriculture

University, 5Hunan Agricultural University, 6Sichuan Academy of Agricultural Sciences,7Zhejiang University

(linshan@cau.edu.cn)

Rice production is facing severe water scarcityeven in Southern China, in Guangdong with annual precipitation of 2000 mm

© www.irri.org/ipswar

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Rice

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Average yield of rice, corn and wheat in China

Disadvantages of lowland rice production systems:

• High water demand , hence low water use efficiency

Wheat 500

Rice 1900

(Pimentel, 1997b)

Amount of water required (in liters) for the production of 1 kg grain

Water consumption for lowland productiondaily Season (150 d)mm d-1 mm

Land preparation 175 – 750Evapotranspiration wet season 4 – 5 600 – 750 dry season 6 – 7 900 – 1050Seepage heavy clays 1 – 5 150 – 750 loamy/sandy soil 25 – 30 3750 – 4500

Total season 925 – 5800 mmTypical 1500 – 2000 mm

(Bouman, 2001)

Disadvantages of lowland rice production systems:

• High water demand, and hence low water use efficiency

• Low N- fertiliser use efficiency

• High methane emission, and thus high global warming potential

Water-saving Ground Cover Rice Production System (GCRPS)

Strategy I: Rice is direct seeded, and soil is irrigated to approximately 80% of field water-holding capacity Strategy II: Rice plant is transplanted, and soil is irrigated to maintain soil water content near saturation

To reduce evaporation, the soil is covered by plastic film or by plant mulch with both strategies

Objectives of water-saving GCRPS

• Increase water and nutrient use efficiency

• Reduce emissions of CH4 and N2O

• Maintain and increase the grain yield

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Beijing, 600 mm

Nanjing, 1000 mm

Gaungzhou, 2000 mm

HubeiSichuan

Zhejiang

Distribution of precipitationGCRPS – direct seeding

GCRPS – transplanting

• GCRPS - direct seedingGCRPS - direct seeding

Seeding GCRPS-film

(15 cm pF < 10–15 kPa)

Lin, 2002

• GCRPS - transplanting

Lin, 2002

• Rice plant will be transplanted and soil is irrigated to maintain soil water content near saturation• To reduce evaporation, the soil is covered by plastic film or plant mulch.

Transplanting Lin, 2005

Land level & fertilization Film covering

Hole making

林杉 , 2005

Layout of the field experiment in Hubei

Evapo-transpiration plus leachingFree surface evaporation

Free surfaceevaporation

Evapo-transpiration

Free surface evapo-ration between rows

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Amount of irrigation water used for paddy ground cover with plastic film and with straw

Paddy Film Straw

Beijing Nanjing Guangzhou

Paddy Film Straw Paddy Film Straw

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Irrigation water use efficiency

Paddy Film Straw

Beijing Nanjing Guangzhou

Paddy Film Straw Paddy Film Straw

photo Lin

May we reduce CH4/N2O emission of traditional paddy rice?

Closed Chamber

15N balance

Water balance

Nitrate leaching

Water meter

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CH4 emissions

Paddy Film Straw

Beijing Nanjing Guangzhou

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Compared to CO2: CH4 by factor of 23, N2O by factor of 296 (IPCC 2001)

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Global warming potential of CH4 and N2O

Paddy Film Straw

Beijing Nanjing Guangzhou

Paddy Film Straw Paddy Film Straw

Evaluation of water-saving alternatives with GCRPS

Comparison of rice grain yield, 2002

Beijing Nanjing Guangzhou

Regional yield level

Average grain yield (kg ha-1) of long-term experiments

Treatment Sichuan Hubei Nanjing Zhejiang (1999-2008) (2003-2008) (2001-2008) (2001-2008)

Paddy -N0 nd 3,180 4,631 nd

GCRPS-N0 5,011 4,657 4,330 6,318

Paddy -N150 5,998 6,059 7,294 8,216

GCRPS-N150 7,051 6,631 6,636 7,766

150 kg N/ha/yr for Sichuan, Hubei & Nanjing; 135 kg N/ha/yr for Zhejiang

+18% +10% -9% -5%

+46% -6%

Average grain yield, N uptake, NUE and C-fixation at Hubei , 2003-08

Treatment Yield N-uptake C-fix. NUE* (kg/ha) (kg N/ha) (kg C/ha) (%)

Paddy -N0 3,180 45 2,762

GCRPS-N0 3,657 50 3,388

Paddy -N150 6,059 111 5,663 44

GCRPS-N150 6,631 123 6,310 52

-- Difference method-- 150 kg N/ha/yr, n=18

Is there still some room for maneuver

for us to increase the rice grain yield

and reduce N2O emission of GCRPS by

improvement of fertilization method?

Average grain yield, N uptake, NUE and C-fixation at Hubei, 2003-08

Treatment Yield N-uptake C-fix. NUE* (kg/ha) (kg N/ha) (kg C/ha) (%)

Paddy -N0 3,180 45 2,762

GCRPS-N0 3,657 50 3,388

Paddy -N150 6,059 111 5,663 44

GCRPS-N150 6,631 123 6,310 52

GCRPS-CRF* 6,805 134 6,876 59

GCRPS-Ninhibitor** 6,945 133 6,550 59

• *Average for 5 years; ** Average for 4 years; • 150 kg N/ha/yr for all fertilized treatment

+13%

+24%

+18%

100%

Paddy _N225 0.05 c 123 c

GCRPS_N225 0.20 a 490 a

GCRPS_N150 0.12 b 293 b

GCRPS_CRF 0.07 c 160 c

AvdFlux Total

(mg.m-2.h-1) (mg.m-2)

Average daily N2O flux (AvdFlux) and total emission during the whole rice growth period (Total)

(Fan, unpub., pers. comm.)

Covering with plastic film

Hole-making with simple tool

Water-saving rice GCRPS in practice

GCRPS in Hubei

2005.5.7

GCRPS in Sichuan

2009.5.27

Conclusion

The system of water-saving ground cover rice production

can maintain food safety, improve resource use efficiency

(both for water & N), and increase C-fixation. Also, it can

also decrease global warming potential by reducing CH4

emissions and has the potential to reduce N2O emissions.

We believe GCRPS can harmonize the objectives of Countering Water Scarcity, Enhancing Food Safety, Achieving Resource Use Efficiency, and Abating Global Warming Potential

Thanks for your attention