Contributors: S Lin, K. Dittert, HB Tao1, KR Shen, YC Xu, SW Gao, XL Fan, MS Fan, SH Lu, LH Wu, FS Zhang. China Agriculture University, University of Kiel, Agricultural Bureau Hubei, Nanjing Agriculture University, Hunan Agricultural University, Sichuan Academy of Agricultural Sciences, Zhejiang University

1. Agronomic and environmental evaluation of a new approach for water-saving ground cover rice production system (GCRPS) S Lin 1 、 K. Dittert 2 、 HB Tao 1 、 KR Shen 3 、 YC Xu 4 、 SW Gao 4 、 XL Fan 5 、 MS Fan 1 、 SH Lu 6 、 LH Wu 7 、 FS Zhang 1 1 China Agriculture University, 2 University of Kiel, 3 Agricultural Bureau Hubei, 4 Nanjing Agriculture University, 5 Hunan Agricultural University, 6 Sichuan Academy of Agricultural Sciences, 7 Zhejiang University (linshan@cau.edu.cn)

2. Rice production is facing severe water scarcity even in Southern China, in Guangdong with annual precipitation of 2000 mm © www.irri.org/ipswar

3. Rice Corn Wheat Yield (kg/ha) year Average yield of rice, corn and wheat in China 0 1000 2000 3000 4000 5000 6000 7000 76 78 80 82 84 86 88 90 92 94 96 98 00

5. Wheat 500 Rice 1900 (Pimentel, 1997b) Amount of water required (in liters) for the production of 1 kg grain

6. Water consumption for lowland production daily Season (150 d) mm d -1 mm Land preparation 175 – 750 Evapotranspiration wet season 4 – 5 600 – 750 dry season 6 – 7 900 – 1050 Seepage heavy clays 1 – 5 150 – 750 loamy/sandy soil 25 – 30 3750 – 4500 Total season 925 – 5800 mm Typical 1500 – 2000 mm (Bouman, 2001)

8. 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

10. 4000 3000 2000 1600 1400 1200 1000 800 600 400 200 100 50 Beijing, 600 mm Nanjing, 1000 mm Gaungzhou, 2000 mm Hubei Sichuan Zhejiang Distribution of precipitation GCRPS – direct seeding GCRPS – transplanting

13. Lin, 2005 Transplanting Land level & fertilization Film covering Hole making

14. 林杉 , 2005 Layout of the field experiment in Hubei

15. Evapo-transpiration plus leaching Free surface evaporation Free surface evaporation Evapo-transpiration Free surface evapo-ration between rows

16. Amount of irrigation water used for paddy ground cover with plastic film and with straw Irrigation water (mm) Paddy Film Straw Beijing Nanjing Guangzhou Paddy Film Straw Paddy Film Straw 0 1000 2000 3000

17. Irrigation water use efficiency 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 WUEi (kg m -3 ) Paddy Film Straw Beijing Nanjing Guangzhou Paddy Film Straw Paddy Film Straw 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

18. photo Lin May we reduce CH 4 /N 2 O emission of traditional paddy rice? Closed Chamber 15 N balance Water balance Nitrate leaching Water meter

19. CH 4 emissions 0 1000 2000 3000 4000 20000 0 1000 2000 3000 4000 20000 CH 4 (mg m -2 ) Paddy Film Straw Beijing Nanjing Guangzhou Paddy Film Straw Paddy Film Straw 0 1000 2000 3000 4000 20000

20. N 2 O emissions 0 500 1000 1500 0 500 1000 1500 0 500 1000 1500 N 2 O (mg m -2 ) Paddy Film Straw Beijing Nanjing Guangzhou Paddy Film Straw Paddy Film Straw

21. Global warming potential of CH 4 and N 2 O 0 200 400 0 200 400 0 200 400 Compared to CO2: CH 4 by factor of 23, N 2 O by factor of 296 (IPCC 2001) CO 2 equivalent flux (g m -2 ) Paddy Film Straw Beijing Nanjing Guangzhou Paddy Film Straw Paddy Film Straw

22. Evaluation of water-saving alternatives with GCRPS Comparison of rice grain yield, 2002 Beijing Nanjing Guangzhou Regional yield level

23. Evaluation of water-saving alternatives with GCRPS Comparison of fertiliser nitrogen use efficiency, 2002 Fertiliser productivity: kg grain kg N fertiliser -1 Beijing Nanjing Guangzhou

24. 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%

25. 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

26. Is there still some room for maneuver for us to increase the rice grain yield and reduce N 2 O emission of GCRPS by improvement of fertilization method?

28. 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 N 2 O flux (AvdFlux) and total emission during the whole rice growth period (Total) (Fan, unpub., pers. comm.)

29. Covering with plastic film Hole-making with simple tool Water-saving rice GCRPS in practice

30. GCRPS in Hubei 2005.5.7

31. GCRPS in Sichuan 2009.5.27

32. 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 CH 4 emissions and has the potential to reduce N 2 O emissions. We believe GCRPS can harmonize the objectives of Countering Water Scarcity , Enhancing Food Safety , Achieving Resource Use Efficiency , and Abating Global Warming Potential

33. Thanks for your attention